Book VI (part 1 of 3)

Book VI (part 1 of 3)

Throughout this last Book, Gilbert glories in the Copernican theory, the open, unquestioned, advocacy and endorsement of which according to many seems, after all, to have been the object of the work. He maintains that the magnetic axis of the earth remains invariable; he treats of the daily magnetic revolution of the globes, as against the time-honoured opinion of a primum mobile, the fixed stars being at different distances from the earth; of the circular motion of the earth and of its primary magnetic nature, whereby her poles are made different from the poles of the ecliptic, as well as of the precession of the equinoxes and of the obliquity of the zodiac.

According to Humboldt,[37] Gilbert was the first to make use of the words electric force, electric emanations, electric attraction, but, he says, there is not found in “De Magnete” either the abstract expression electricitas or the barbarous word magnetismus introduced in the seventeenth century. We likewise owe to Gilbert the words equator, magneticum, terrella, versorium and verticitas, but not the word pole, which had before been used by P. Peregrinus and others.

The second edition of “De Magnete” appeared at Stettin in 1628, “embellished with a curious title-page in the form of a monument ... and a fantastic indication of the earliest European mariner’s compass, a floated lodestone, but floating in a bowl on the sea and left behind by the ship sailing away from it.”[38]

The third edition was also published at Stettin during 1633. Gilbert left, besides, a posthumous work, “De Mundo Nostro Sublunari Philosophia Nova,” Amsterdam, 1651, which latter, says Prof. Robison, consists of an attempt to establish a new system of natural philosophy upon the ruins of the Aristotelian doctrine.[39]

To give here such an analysis as Gilbert’s admirable work merits would be impracticable, but the short review of it made by Prof. Robison (at p. 209 of his “System of Mechanical Philosophy,” London, 1822) deserves full reproduction, as follows: “In the introduction, he recounts all the knowledge of the ancients on the subject treated, and their supine inattention to what was so entirely in their hands, and the impossibility of ever adding to the stock of useful knowledge, so long as men imagined themselves to be philosophizing, while they were only repeating a few cant words and the unmeaning phrases of the Aristotelian school. It is curious to mark the almost perfect sameness of Dr. Gilbert’s sentiments and language with those of Lord Bacon. They both charge, in a peremptory manner, all those who pretend to inform others, to give over their dialectic labours, which are nothing but ringing changes on a few trite truths, and many unfounded conjectures, and immediately to betake themselves to experiment. He has pursued this method on the subject of magnetism, with wonderful ardour, and with equal genius and success; for Dr. Gilbert was possessed both of great ingenuity, and a mind fitted for general views of things. The work contains a prodigious number and variety of experiments and observations, collected with sagacity from the writings of others, and instituted by himself with considerable expense and labour. It would, indeed, be a miracle if all of Dr. Gilbert’s general inferences were just, or all his experiments accurate. It was untrodden ground. But, on the whole, this performance contains more real information than any writing of the age in which he lived, and is scarcely exceeded by any that has appeared since. We may hold it with justice as the first fruits of the Baconian or experimental philosophy.” Elsewhere, Prof. Robison remarks: “It is not saying too much of this work to affirm that it contains almost everything we know of magnetism. His unwearied diligence in searching every writing on the subject and in getting information from navigators, and his incessant occupation in experiments, have left very few facts unknown to him. We meet with many things in the writings of posterior inquirers, some of them of high reputation and of the present day, which are published and received as notable discoveries, but are contained in the rich collection of Dr. Gilbert.”

The Rev. Wm. Whewell says in his “History of the Inductive Sciences” (Vol. III. p. 49) that in the “De Magnete,” a book of only 240 pages, upon which Dr. Gilbert has been engaged for nearly eighteen years, are contained “all the fundamental facts of the science, so fully examined, indeed, that, even at this day, we have little to add to them.”

Dr. John Davy remarks (“Memoirs of the Life of Sir Humphry Davy,” London, 1836, Vol. I. p. 309): “Gilbert’s work is worthy being studied, and I am surprised that an English Edition (translation) of it has never been published.” He also alludes to the well-known reproach thrown upon Gilbert’s philosophy by Francis Bacon, who, in his “De Augmentis Scientiarum,” observes that “Gilbert has attempted to raise a general system upon the magnet, endeavouring to build a ship out of materials not sufficient to make the rowing-pins of a boat.” On the other hand, Digby and Barlowe place Gilbert upon a level with Harvey, Galileo, Gassendi and Descartes (“Nouvelle Biographie Générale,” 1858, Vol. VIII. p. 494) while the celebrated historian of the Council of Trent, Fra Paolo Sarpi--who will not be thought an incompetent judge--names Gilbert, with Francis Vieta (the greatest French mathematician of the sixteenth century) as the only original writer among his contemporaries (“Lettere di Fra Paolo,” p. 31; Hallam, “Intro. to Lit.,” 1859, Vol. II. p. 464).

In Thos. Thomson’s “History of the Royal Society,” London, 1812, the “De Magnete” is thus alluded to: “Dr. Gilbert’s book on magnetism, published in 1600, is one of the finest examples of inductive philosophy that has ever been presented to the world. It is the more remarkable because it preceded the ‘Novum Organum’ of Bacon, in which the inductive method of philosophizing was first explained.” How far Gilbert was ahead of his time is best proven by the works of those who wrote on magnetism during the first few decades after his death. They contributed in reality nothing to the extension of this branch of physical science. Poggendorff, from whose “Geschichte der Physik,” p. 286, this is extracted, as already stated, calls Gilbert “the Galileo of Magnetism.” By Dr. Priestley, he was named “the Father of Modern Electricity.”

The tribute of Henry Hallam is to the following effect: “The year 1600 was the first in which England produced a remarkable work in physical science; but this was one sufficient to raise a lasting reputation for its author. Gilbert, a physician, in his Latin treatise on the magnet, not only collected all the knowledge which others had possessed on the subject, but became at once the father of experimental philosophy in this island, and, by a singular felicity and acuteness of genius, the founder of theories which have been revived after a lapse of ages, and are almost universally received into the creed of science. Gilbert was one of the earliest Copernicans, at least as to the rotation of the earth, and, with his usual sagacity, inferred, before the invention of the telescope, that there are a multitude of fixed stars beyond the reach of our vision” (“Introduction to the Literature of the Fifteenth, Sixteenth and Seventeenth Centuries,” London, 1859, Vol. II. p. 463).

In the “Principal Navigations ...” Edinburgh, 1889, Vol. XII. p. 10, Richard Hakluyt speaks of “... my worshipfull friend M. douctour Gilbert, a gentleman no lesse excellent in the chiefest secrets of the Mathematicks (as that rare iewel lately set forth by him in Latine doeth euidently declare) then in his oune profession of physicke.”

We conclude this account of Gilbert in the quaint words of old Dr. Fuller: “He has (said my informer[40]) the clearness of Venice Glass without the Brittleness thereof, soon Ripe and long lasting is his Perfection. He commenced Doctor in Physick, and was Physician to Queen Elizabeth, who stamped on him many marks of her Favour, besides an annuall Pension to encourage his studies. He addicted himself to Chemistry, attaining to great exactness therein. One saith of him that he was Stoicall, but not Cynicall, which I understand Reserved; but not Morose, never married, purposely to be more beneficial to his brethren. Such his Loyalty to the Queen that, as if unwilling to survive, he dyed in the same year with her, 1603. His Stature was Tall, Complexion Chearful, an Happiness not ordinary in so hard a student and so retired a person. He lyeth buried in Trinity Church in Colchester under a plain monument.”

“Mahomet’s Tombe, at Mecha, is said strangely to hang up, attracted by some invisible Loadstone, but the memory of this Doctor will never fall to the ground, which his incomparable book ‘De Magnete’ will support to eternity” (“The History of the Worthies of England Endeavoured by Thomas Fuller, D.D.,” London, 1662, p. 332--Essex).

In his Epistle to Dr. Walter Charleton, physician in ordinary to King Charles I (Epist. III. p. 15, Vol. XI of the Works of Dryden, London, 1803) the celebrated English poet predicts that:

“_Gilbert shall live till loadstones cease to draw Or British fleets the boundless ocean awe._”

REFERENCES.--“La Grande Encyclopédie,” Vol. XVIII. p. 930; “Dictionary of National Biography,” London, 1890, Vol. XXI. p. 338; “Bibliographica Britannica,” London, 1757, Vol. IV. p. 2202; Larousse, “Dict. Univ.,” Vol. VIII. p. 123; “Freeman’s Historic Towns” (Colchester), by Rev. E. L. Cutts, 1888, p. 172; “Beauties of England and Wales,” by E. W. Brayley and John Britton, 1810, Vol. V. (Colchester) pp. 318–319; Cooper, “Athenæ Cantabrigienses,” Cambridge, 1858; Anthony à Wood, “Athenæ Oxonienses,” London, 1813, Vol. I; Thomas Wright, “Hist. and Top. of the County of Essex,” 1866, Vol. I; “Journal des Savants” for June 1859, Sept. 1870; Wm. Munk, “The Roll of the Royal College of Physicians of London,” 1878, Vol. I. p. 77; Humboldt, “Cosmos,” 1859–1860, Vol. I. pp. 158–159, note, 177, 179, 182, note; Vol. II. pp. xvii, 279–281, 334–335, 341–342; Vol. V. p. 58 for references to and extracts from Dr. Gilbert’s work; Wm. Whewell, “Hist. of the Ind. Sciences,” Vol. I. pp. 274–275, 394; Vol. II. pp. 192, 217–220, 224, 225, and “Philosophy of the Ind. Sciences,” London, 1840, Vol. II. pp. 374–379; “Mémoires de Physique,” Lausanne, 1754, pp. 123, etc.; “U.S. Magnetic Tables and Isogonic Charts for 1902,” L. A. Bauer, pp. 1–77; “Popular Science Monthly,” August 1901, pp. 337–350 for “Gilbert of Colchester,” by Bro. Potamian, also its translation in “Ciel et Terre” for Dec. 1, 1902, pp. 472–480 and for Dec. 16, 1902, p. 489; “New International Encyclopædia,” New York, 1903, Vol. VIII. p. 368; “William Gilbert of Colchester,” by Conrad Wm. Cooke, London, 1890 (reprinted from “Engineering,” 1889); “William Gilbert of Colchester,” by Dr. Silvanus P. Thompson, London, 1891; “William Gilbert of Colchester,” a translation by P. Fleury Mottelay, New York and London, 1893; “William Gilbert of Colchester,” a translation by members of the Gilbert Club, London, 1900, to which is appended a valuable collection of “Notes on the De Magnete” of Dr. William Gilbert, by Dr. Silvanus P. Thompson, who therein also gives an interesting bibliography of this great work; “William Gilbert of Colchester,” a sketch of his magnetic philosophy by Chas. E. Benham, Colchester, 1902; “Zur bibliographie von W. Gilbert’s De Magnete,” Von. G. Hellmann (“Terrestrial Magnetism and Atmospheric Electricity” for June 1902); “Terr. Magn. and Atm. Elect.,” Vol. II. p. 45 for “The Earth a Great Magnet,” by J. A. Fleming; “The Earth a Great Magnet,” by Prof. Alfred M. Mayer, New York, 1872; Philip Morant, “History and Antiquities of Colchester,” London, 1748; Bacon, “Novum Organum,” Leyden, 1650, pp. 263–265; Rees’ “Encyclopædia,” 1819, Vol. XVI. article “Gilbert”; “A Course of Lectures on Natural Philosophy and the Mechanical Arts,” by Thos. Young, London, 1807, Vol. I. pp. 686, 747, 756; Vol. II. pp. 111, 324, 436; “Critical Dictionary of Engl. Literature,” S. Austin Allibone, Philad., 1888, Vol. I. p. 668; “General Biographical Dictionary,” John Gorton, London, 1833, Vol. II, mentioning Wood’s “Athen. Ox.,” Hutchinson’s “Biog.-Med.,” and Aikin’s “G. Biography”; Phil. Trans. for 1667, Vol. II. pp. 527–531, also Baddam’s abridgments, London, 1739, Vol. III. p. 129 and London, 1745, Vol. I. p. 97.

=A.D. 1601.=--Brahé (Tycho--Tygge--Thyghe--Tyge), who has been several times mentioned in this compilation and is referred to by Gilbert (“De Magnete,” Book IV. chap. xii. also Book VI. chap. v.), was a distinguished Danish astronomer (b. 1546, d. 1601), the founder of modern astronomical calculations, whose investigations and records of the positions of the stars and planets made possible the brilliant discoveries of Kepler and Newton. As Humboldt expresses it, the rich abundance of accurate observations furnished by Tycho Brahé, himself the zealous opponent of the Copernican system, laid the foundation for the discovery of those eternal laws of planetary movements which prepared imperishable renown for the name of Kepler, and which, interpreted by Newton, proved to be theoretically and necessarily true, have been now transferred into the bright and glorious domain of thought as the intellectual recognition of nature (“Cosmos,” 1860, Vol. II. p. 313).

As his very able biographer, Dr. J. L. E. Dreyer, of the Armagh Observatory, remarks in his admirable work (Edinburgh, 1890): “Without Brahé, Kepler never could have found out the secrets of the planetary motions, and, in the words of Delambre, ‘Nous ignorerions peut être encore le véritable système du monde.’ The most important inheritance which Tycho left to Kepler and to posterity was the vast mass of observations all which, Kepler justly said, ‘deserved to be kept among the royal treasures, as the reform of astronomy could not be accomplished without them ...’ at one breath blowing away the epicycles and other musty appendages which disfigured the Copernican system.... Tycho Brahé had given Kepler the place to stand on and Kepler did move the world!”

Brahé was the first to recognize the variation, i. e. the inequality, in the moon’s motion. In opposition to the opinion of Sédillot, M. Biot maintains that this fine discovery of Tycho by no means belongs to Abul-Wefa, and that the latter was acquainted not with the “variation” but only with the second part of the “evection” (“Cosmos,” 1860, Vol. II. p. 222, wherein are many references to the Comptes Rendus and to the “Journal des Savants”).

The biographical division of the “English Cyclopædia,” 1866, Vol. I. pp. 898–903, gives a list of Brahé’s numerous writings, headed by his earliest publication, “De Nova Stella,” 1573, which is so extremely rare that, until 1890, when Dr. Dreyer gave a description of it, not a single historian of astronomy had ever seen it or been able to even give its title correctly (“Journal of Br. Astron. Assoc.,” Vol. XII. No. 2, p. 95; Houzeau et Lancaster, Vol. II. p. 598). A detailed account of its contents is given at pp. 44–56 of Dr. Dreyer’s 1890 work above alluded to, wherein we are further told of the protection given Brahé by the Landgrave William of Hesse-Cassel, as well as of the consequent aid so liberally extended by King Frederick II. Reference is likewise made to the fact that in December 1584 the King turned to Tycho for help, writing that he was under the impression he had returned a compass made by Tycho, believing there was something wrong with it; that, if this proved to be the case, Tycho was to send back the compass, but, if not, he was to make two new ones similar to the old one (F. R. Friis, “Tyge Brahé,” p. 147).

REFERENCES.--“Life of Tycho Brahé,” by Gassendi, containing the “Oratio Funebris,” etc., of John Jessenius; Tessier “Eloges des hommes illustres,” Vol. IV. p. 383; Blount, “Censura,” etc.; “Epistolæ ad Joh. Keplerum,” 1718; Riccioli, “Chronicon in Almagesto Novo,” Vol. I. p. 46; the biography by Malte-Brun in the “Biog. Univ.,” wherein is to be found the list of all of Tycho Brahé’s writings; “English Cycl.,” Supplement to Biography, p. 376, at Scipione Chiaromonti, for “Anti-Tycho”; “Bulletin de la Société Astronomique de France,” Janvier 1903; “Journal des Savants,” Juin 1864; Humboldt, “Cosmos,” 1860, Vol. III. pp. 158, 160, 162; “Nature” of Dec. 27, 1900, p. 206, and “Nature,” Vol. LXV. pp. 5–9, 104–106, 181, as well as the “Bulletin Astronomique,” Paris, Avril 1902, pp. 163–166, for account of the celebrations of the Tercentenary of Tycho-Brahé’s death, held at Prague and elsewhere, on Oct. 24, 1901, with illustrations of his observatory, etc. etc.; “Geschichte der Mathem. von Abraham G. Kästner,” Vol. II. pp. 376, etc., 613, etc.; R. A. Proctor, “Old and New Astronomy,” 1892 passim; “Biog. Génér.,” 1890, Vol. XLV. pp. 750, 755; “La Grande Encycl.,” Vol. VII. pp. 962–963; Larousse, “Dict. Univ.,” Vol. XV. pp. 613–614; “Encycl. Brit.,” Edin., 1876, Vol. IV. p. 200.

Consult likewise for Abul Wefa: “Le Journal des Savants,” for Nov. 1841, Sept. 1843, Mar. 1845 and Oct. 1871; Houzeau et Lancaster, “Bibliog. Gén.,” 1887, Vol. I. pp. 598–600, and Vol. II. pp. 92–93; “Bull. de la Soc. Acad. de Laon,” Janvier 1903, pp. 40–48; Leopold Von Ranke, “History of England,” Vol. I. p. 367 and notes; Wm. Whewell, “Phil. of the Ind. Sc.,” London, 1840, Vol. II. pp. 386–388; Harold Höffding, “A Hist. of Mod. Phil.,” translated by B. E. Mayer, London, 1900, Vol. I. p. 428.

=A.D. 1602.=--Blundeville (Thomas) publishes at London, “The Theoriques of the Seuen Planets,” etc., which, as the lengthy title goes to show, indicates “the making, description and vse of two ingenious and necessarie instruments for sea men to find out thereby the latitude of any place upon the sea or land, in the darkest night, that is, without the helpe of sunne, moone or starre; first invented by M. Dr. Gilbert, a most excellent philosopher, and one of the ordinarie physicians to Her Majestie.”

He had previously published, in 1589, “A briefe description of universal mappes and cardes and of their use; and also the use of Ptolemy his Tables,” which was followed, during 1594, by his well-known work on navigation. From the rare sixth edition of the latter (London, 1622) the curious title page is worth reproducing as follows: “M. Blundeville, His Exercises, contayning eight treatises, the titles whereof are set down in the next printed page: which treatises are very necessary to be read and learned of all Young Gentlemen that haue not beene exercised in such Disciplines and yet are desirous to haue knowledge as well in Cosmographie, Astronomie and Geographie, as also in the art of navigation, in which art it is impossible, to profit without the helpe of these or such like Instructions. To the furtherance of which Art of Navigation the sayd Master Blundeville especially wrote the said Treatises and of meere good will doth dedicate the same to all Young Gentlemen of this Realme.” The contents of this curious work treat of Arithmetic, Cosmography, Terrestrial and Celestial Globes, Peter Plancius, his Universal Map, Mr. Blagrau, his Astrolabe, The First Principles of Navigation, etc. etc.

The Mr. Blagrau here mentioned is John Blagrave, eminent English mathematician, author of “The Mathematical Jewel,” as well as of “The making and use of the familiar staffe,” of “The Art of Dialling,” and of “Astrolabium Uranicum Generale, a necessary and pleasunt solace and recreation for Navigators in their long journeying, containing the use of an instrument or astrolabe.” From the last named, it appears that Blagrave was a convert to the heliocentric theory of Copernicus (“New Gen. Biog. Dict.,” by Rev. H. J. Rose, London, 1850, Vol. IV. p. 277). The invention of the dipping needle by Mr. Blagrave was before the discovery of the change of the needle’s variation by Mr. Gellibrand (“Philos. Britan.,” Benj. Martin, London, 1771, Vol. I. p. 46).

REFERENCES.--“Gen. Biogr. Dict.” (Gorton), London, 1833, Vol. I; Hutton’s abridgments of the Phil. Trans., London, 1739, Vol. IV. p. 103; “Dict. of Nat. Biog.,” Leslie Stephen, London, 1886, Vol. V. pp. 157 and 271–272; “Gen. Biog. Dict.,” Alex. Chalmers, London, 1812, Vol. V. pp. 370–371; “Biog. Univ.,” Paris, 1843, Vol. IV. p. 397; “Nouv. Biog. Générale” (Hœfer), Paris, 1853, pp. 170–171; Baddam’s abridgments of the Phil. Trans., London, 1739, Vol. IV. p. 103; “Ames’ Typog. Antiq.” (Herbert), pp. 693, 694, 697–701; Bloomfield’s “Norfolk,” Vol. LXIV. pp. 68–70; Cooper’s “Athenæ Cantab.”; Davy’s “Suffolk Coll.,” Vol. LXXXIX. p. 215; Hazlitt, “Coll. and Notes,” 1876, also the second series.

=A.D. 1609.=--Kepler (Johann), who succeeded Tycho Brahé in 1601 as astronomer to the German Emperor Rudolph II, is the author of a treatise “On the Magnet,” which was followed, during 1609, by his greatest work, the “Astronomia Nova.” The latter was deemed by Lalande of such importance that he considered it the duty of every astronomer to read it from beginning to end at least once in his lifetime.

The “Astronomia” contains the extraordinary book “on the motion of Mars,” and is said to hold the intermediate place, besides being the connecting link between the discoveries of Copernicus and those of Newton. Kepler’s doctrine is thus enunciated by Dr. Whewell (“Physical Astronomy,” Chap. I): “A certain Force or Virtue resides in the sun by which all bodies within his influence are carried around him. He illustrates (‘De Stella Martis,’ Chap. XXXIV. p. 3) the nature of this Virtue in various ways, comparing it to Light and to the Magnetic Power, which it resembles in the circumstances of operating at a distance, and also in exercising a feebler influence as the distance becomes greater.” In the Table of Contents of the work on the planet Mars, the purport of the chapter to which allusion has been made is stated as follows: “A Physical speculation, in which it is demonstrated that the vehicle of that virtue which urges the planets, circulates through the spaces of the universe after the manner of a river or whirlpool (vortex), moving quicker than the planets.” It will doubtless be found by any one who reads Kepler’s phrases concerning the moving force--the magnetic nature--the immaterial virtue of the sun, that they convey no distinct conception, except so far as they are interpreted by the expressions here quoted: “A vortex of fluid constantly whirling around the sun, kept in this whirling motion by the rotation of the sun himself and carrying the planets around the sun by its revolution, as a whirlpool carries straws, could be readily understood; and though it appears to have been held by Kepler that this current and vortex was immaterial, he ascribes to it the power of overcoming the inertia of bodies, and of putting them and keeping them in motion, the only material properties with which he had anything to do. Kepler’s physical reasonings, therefore amount, in fact, to the doctrine of vortices around the central bodies and are occasionally so stated by himself; though by asserting these vortices to be ‘an immaterial species,’ and by the fickleness and variety of his phraseology on the subject, he leaves his theory in some confusion; a proceeding, indeed, which both his want of sound mechanical conceptions and his busy and inventive fancy might have led us to expect. Nor, we may venture to say, was it easy for any one at Kepler’s time to devise a more plausible theory than the theory of vortices might have been made. It was only with the formation and progress of the science of mechanics that this theory became untenable.”

REFERENCES.--“Kepler, sa vie et ses ouvrages,” in the “Journal des Savants” for June, July and August 1847; Kepler’s manuscripts, “Phil. Trans.,” Vol. XI. p. 27; Wm. Whewell, “Phil. of the Ind. Sc.,” London, 1840, Vol. II. pp. 383–386; “Epistolæ ad J. Keplerum,” published by M. G. Hansch in 1718; Houzeau et Lancaster, “Bibliogr. Générale,” 1887, Vol. I. part i. pp. 612–614, detailing the contents of Kepler’s “Opera Omnia,” also Vol. I. part ii. pp. 1315–1316, 1330–1331, 1383, and Vol. II. pp. 175–176, 456–462 and 1581; Robert Small, “An Account of the Astronomical Discoveries of Kepler,” London, 1804; Humboldt, “Cosmos,” 1860, Vol. II. p. 710, notes, for Laplace, Chasles and Brewster on the writings and theories of Kepler; “Jour. des Savants” for June, July and August 1847; “Geschichte der Mathem.,” Vol. III. p. 318, and Vol. IV. pp. 216, 311; Dr. Geo. Miller, “Hist. Phil. Ill.,” London, 1849, Vol. III. notes at pp. 134–135; Fourth Dissert. of “Encycl. Brit.”; Whewell, “Hist. of the Ind. Sc.,” 1859, Vol. I. pp. 291–311, 320, 386, 387, 415, 462, 532–534, and Vol. II. pp. 55, 56.

It will be well to look at the last-named work of Dr. Whewell for references to Jeremiah Horrox--Horrockes--(1619–1641), the celebrated young English scientist, who wrote in defence of the Copernican opinion in his “Keplerian Astronomy defended and promoted” (“Hist. of the Ind. Sc.,” Vol. I. Book V. chap. iii. p. 276, and Chap. V. p. 303), as well as for references to Giovanni Alfonso Borelli (1608–1679). Borelli, who has by many been erroneously called a pupil of Galileo, was a distinguished Italian physicist and astronomer, born at Naples in 1608, who founded what has been called the iatromathematical school, which, under the protection of Leopold of Tuscany, became known as the Accademia del Cimento. Whewell speaks of him in Vol. I. at Book VI. chap. ii. p. 323, at Book VII. chap i. pp. 387, 393, 394, and at Chap. II. pp. 303, 395, 405, 406. Horrox is mentioned, more particularly, by Houzeau et Lancaster (“Bibliog. Générale,” Vol. II. p. 167), also at pp. 12 and 220, Vol. II of Hutton’s abridgments of the Phil. Trans.; while full accounts of the many important works of Borelli are to be found in “Biogr. Générale,” Vol. VI. pp. 700–701; Ninth “Britannica,” Vol. IV. p. 53; Larousse, “Dict. Univ.,” Vol. II. p. 1003; “Chambers’ Encycl.,” 1888, Vol. II. p. 328; “La Grande Encycl.,” Vol. VII. p. 405; Nicéron, “Mémoires,” Vol. VIII. p. 257; Vigneul-Marville, “Mélanges,” Vol. II. p. 122; Sachs, “Onomasticon Literarium,” V. 40; Hagen, “Memoriæ Philosophorum,” Frankfort, 1710.

=A.D. 1613.=--Ridley (Marke), “Doctor in physicke and philosophie, latly physition to the Emperour of Russia and one of ye eight principals or elects of the College of Physitions in London,” is the author of a small quarto entitled “A Short Treatise of Magnetical Bodies and Motions,” published in London, 1613. Of this treatise, Libri says that the author, in his preface, deals tolerantly with the many and varied theories concerning magnetic bodies, instancing many of the most notable from those of Pliny and Nicander to those of Robert Norman. He is particularly emphatic concerning the production of perpetual motion by means of the loadstone, finding it “by the experience of many ingenious practices ... impossible to be done.”

From the notice given him in “Dict. of Nat. Biog.,” 1896, Vol. XLVIII. pp. 285–286, we learn that in the above-named work, he claims acquaintance with William Gilbert, whom he commends as the greatest discoverer in magnetical science, and that after giving twenty-four chapters on the properties and description of the magnet, he discusses the variation of the compass and methods of estimating it in eight chapters, the inclinatory needle in eight others, concluding with a chapter on finding the longitude and one “of the matter of the magnetical globe of the earth by the needle.”

In 1617, he published “Animadversions on a late work entitled Magnetical Advertisement; or, Observations on the Nature and Properties of the Loadstone.”

=References.=--A. Watt, “Bibliotheca Britannica,” Vol. II. p. 804, at p. 75_g_ Vol. I. of which (article, “Wm. Barlowe”) is “A briefe discovery of the idle animadversions of Marke Ridley, M.D.,” upon a treatise entitled “Magneticall Advertisements,” London, 1618. Consult also “The Lancet” of August 7, 1897, p. 349; Munk’s “College of Phys.,” Vol. I. p. 106; Ridlon’s “Ancient Ryedales,” p. 425.

=A.D. 1616.=--Schouten (Guillaume Cornelissen--Willem Cornelisz), Dutch navigator, indicates points lying in the midst of the Pacific and south-east of the Marquesas Islands in which the variation is null. Humboldt alludes to this (“Cosmos,” 1859, Vol. I. p. 182, and Vol. V. p. 59) and says, “Even now there lies in this region a singular, closed system of isogonic lines, in which every group of the internal concentric curves indicates a smaller amount of variation.”

For Schouten, consult “Relation,” published by Aris Classen, Amst., 1617; Larousse, “Dict. Univ.,” Vol. XIV. p. 375.

Under this same date, A.D. 1616, Chas. Pickering tells us that Wm. Baffin (Churchill Coll. and Anders. II. 268) continued North to “seventy-eight degrees,” as far as a Sound called by him “Thomas Smith’s,” where the compass varied “fifty-six degrees to the westward,” making the true North bear N.E. by E. The northern expanse of water received the name of “Baffin’s Bay” (“Chron. Hist. of Plants,” Boston, 1879, p. 933).

=A.D. 1617.=--Strada (Famianus), an Italian author and Jesuit priest, publishes his curious “Prolusiones Academicæ,” wherein he describes (lib. ii. prol. 6) a contrivance consisting of two magnetic needles attached to two dials each bearing a circle of letters so arranged that when one needle is made to point to any letter on one dial, the other needle points to the same letter upon the other dial.

The description is best given in his own words taken from the original Latin (Stradæ, “Prol. Acad.,” Oxoniæ, 1662, “Magnes cur ferrum aut aurum trahat,” pp. 326–335): “... If you wish your distant friend, to whom no letter can come, to learn something, take a disc or dial, and write round the edge of it the letters of the alphabet in the order in which children learn them, and, in the centre, place horizontally a rod, which has touched a magnet, so that it may move and indicate whatever letter you wish. Then a similar dial being in the possession of your friend, if you desire privately to speak to the friend whom some share of the earth holds far from you, lay your hand on the globe, and turn the movable iron as you see disposed along the margin of all the letters which are required for the words. Hither and thither turn the style and touch the letters, now this one, and now that.... Wonderful to relate, the far-distant friend sees the voluble iron tremble without the touch of any person, and run now hither, now thither; conscious he bends over it and marks the teaching of the rod. When he sees the rod stand still, he, in his turn, if he thinks there is anything to be answered, in like manner, by touching the various letters, writes it back to his friend....”

REFERENCES.--“The Student; or, Oxford and Cambridge Misc.,” 1750, Vol. I. p. 354; Abbé Moigno’s “Traité de Tel. Elec.,” p. 58; Addison (Joseph), “Spectator” for December 6, 1711, No. 241 (p. 273, Vol. II. London ed., 1854); the “Guardian” for 1713, No. 119, and “Nature,” Vol. XVI. pp. 268, 269. Also “Academy and Literature” of January 7, 1905. Zachary Grey, in 1744 edition of Butler’s “Hudibras,” quotes from the “Guardian.”

=A.D. 1620.=--Bacon (Sir Francis), by many considered the greatest of English philosophers and philosophical writers (1561–1626), who was knighted in 1603, became Earl of Verulam in 1618 and Viscount St. Albans in 1620, produces the masterpiece of his genius, the “Novum Organum,” after having twelve times copied and revised it. The last-named work, observes Macaulay, “takes in at once all the domains of science--all the past, the present and the future, all the errors of two thousand years, all the encouraging signs of the passing times, all the bright hopes of the coming age.” Prof. Playfair says of it that “the power and compass of the mind which could form such a plan beforehand, and trace not merely the outline but many of the most minute ramifications of sciences which did not yet exist, must be an object of admiration to all succeeding ages.”

It was Sir John Herschel who remarked that “previous to the publication of the ‘Novum Organum’ natural philosophy, in any legitimate and extensive sense of the word, could hardly be said to exist.” In the address presented in 1623 by the University of Oxford to Sir Francis Bacon, he is represented “as a mighty Hercules who had by his own hand greatly advanced those pillars in the learned world which by the rest of the world were supposed immovable.”

Treating of the electric fluid, Bacon has given (“Physiological Remains,” London, 1648) a detailed list of attractive and non-attractive bodies and the results of his very extensive experiments and observations in physical science generally, as well as of the investigations contained in Dr. Gilbert’s work. To the latter, however, many allusions had already been made in Bacon’s “The Advancement of Learning,” published during 1605, two years before he was made Solicitor-General.

The most satisfactory analyzation of Bacon’s researches is to be found in the attractive edition of his complete works published by Spedding, Ellis and Heath, fifteen volumes, Boston, 1863. Therein will be seen the following references to the magnet and magnetic virtue:

Vol. I. p. 435 (note). In Gilbert’s philosophy, the earth’s magnetic action is not distinguished from gravity (De Mundo, II. c. 3). That the magnetic action of the earth or of a magnet is confined to a definite orb, appears from a variety of passages (see “De Magnete,” II. c. 7, and the definitions prefixed to this work). Gilbert distinguished between the “Orb of Virtue” which includes the whole space through which any magnetic action extends, and the “Orb of Coition” which is totum illud spatium per quod minimum magneticum per magnetem movetur. He asserts that the orb of the magnetic virtue extends to the moon and ascribes the moon’s inequalities to the effects it produces (“De Mundo,” II. c. 19).

Vol. VIII. Aphorisms. “If, before the discovery of the magnet, any one had said that a certain instrument had been invented by means of which the quarters and points of the heavens could be taken and distinguished with exactness ... it would have been judged altogether incredible ...” (pp. 141–142). “The ‘Clandestine Instances’--which I also call ‘Instances of the Twilight’ [the attraction or coming together of bodies]--and which are pretty nearly the opposite of ‘Striking Instances....’ The most remarkable ‘Striking Instance’ is the magnet ... a ‘Clandestine Instance’ is a magnet armed with iron; or, rather, the iron is an armed magnet ...” (pp. 224–226). “The polarity of the iron needle when touched with the magnet” (p. 261). “The magnetic or attractive virtue admits of media without distinction, nor is the virtue impeded in any kind of a medium” (p. 269). “There is no medium known by the interposition of which the operation of the magnet, in drawing iron, is entirely prevented” (pp. 285–286). “A piece of a magnet does not draw so much iron as the whole magnet” (p. 301). “As for the help derived from the virtue of a cognate body, it is well seen in an armed magnet, which excites in iron the virtue of detaining iron by similarity of substance; the torpor of the iron being cast off by the virtue of the magnet” (p. 311). “There are four virtues or operations in the magnet ... the first is the attraction of magnet to magnet, or of iron to magnet, or of magnetised iron to iron; the second is its polarity, and at the same time its declination; the third, its power of penetrating through gold, glass, stone, everything; the fourth, its power of communicating its virtue from stone to iron, and from iron to iron, without communication of substance” (p. 313). “But the flight of iron from one pole of the magnet is well observed by Gilbert to be not a flight strictly speaking, but a conformity and meeting in a more convenient situation” (p. 315). “The magnet endues iron with a new disposition of its parts and a conformable motion, but loses nothing of its own virtue” (p. 318).

Vol. IX. In the fifth book of “De Augmentis Scientiarum,” these questions are asked: (1) A magnet attracts a solid piece of iron; will a piece of a magnet dipped in a dissolution of iron attract the iron itself and so get a coating of iron? (2) Again, the magnetic needle turns to the pole; does it, in so doing, follow the same course as the heavenly bodies? (3) And, if one should turn the needle the wrong way, that is, point it to the South and hold it there for a while, and then let it go; would it, in returning to the North, go round by the West rather than by the East? (pp. 75–76).

Vol. X. This contains, at pp. 269–272, the “Inquiry respecting the Magnet,” of which the original paper is to be found in Vol. IV. pp. 121–125. In Dr. Rawley’s list of works composed by Bacon, during the last five years of his life, this “Inquisitio de Magnete,” first published in 1658, stands last but two. At p. 335 this same Vol. X will be found an extract from “De fluxu et reflexu maris” (“The ebb and flow of the sea”) relative to the inquiry as to whether the earth itself is a magnet, as was asserted by Gilbert.

Besides the “Clandestine Instances” or “Instances of the Twilight” alluded to above, mention could have been made more particularly of Bacon’s observations (in s. 3 of the “Nov. Organ.”) under the direct headings of “Instantiæ Citantes ... Supplementi ... Radii ... Magicæ,” as well as of “Motus Magneticus ... Excitationis ... Fugæ,” etc., which are fully explained at ss. 190–200 of Sir John Herschel’s “Discourse on the study of Natural Philosophy.”

They have been analyzed as follows:

Instantiæ Citantes, to which may be reduced the “discovery of a moving magnetic fluid, or an action circular and perpendicular to the electrical current, yet connected with it.”

Instantiæ Supplementi, such as the magnet which attracts iron through many substances that may be interposed. Perhaps, says he, “some medium may be found to deaden this virtue more than any other medium; such an instance of substitution, would be in the way of degree, or approximation”; that is, it would approach toward destroying the magnetic virtue. Iron possesses, perhaps, this quality in a more marked manner than any other substance.

Instantiæ Radii, leading to the suggestion that there may exist some kind of “magnetic virtue which operates by consent, between the globe of the earth and heavenly bodies; or between the globe of the moon and the waters of the sea; or between the starry heavens and the planets, by which they may be drawn to their apogees,” or greatest distances from the earth.

Instantiæ Magicæ, such as the loadstone animating a number of needles without loss of its own magnetism.

Motus Magneticus, such as the attraction of the heavenly bodies, from an idea, perhaps, that it might be due to a species of magnetism.

Motus Excitationis, such as the new property which is given to iron by the magnet without any loss of power by the latter.

Motus Fugæ, such as “the repulsion of electrified pith balls; also of the similar poles of two magnets. In the latter case, all the force of a strong man has proved insufficient to make the two north poles touch each other.”

The last-named work of Sir John Herschel is alluded to, under the heading of “Prerogative Instances” (“Prærogativæ Instantiarum”) by Thomas Fowler, who calls attention to the fact that among the contemporaries of Francis Bacon by whom the Copernican theory was rejected are: Tycho Brahé (who, however--having died in 1601--did not live to become acquainted with the discoveries of Galileo); Vieta, the greatest mathematician of the sixteenth century (who died as early as 1603); Christopher Clavius (who was employed by Gregory XIII to reform the Calendar and was called the Euclid of his age); and possibly, from his silence, the famous mechanician Stevinus (Delambre, “Histoire de l’Astronomie Moderne”).

REFERENCES.--The works of Sir Francis Bacon, Lord Chancellor of England, by Basil Montagu, 16 vols., London, 1825–1834, and the review thereof made by Thomas Babington Macaulay (“Essays,” 1855, Vol. II. pp. 142–254 (“Edinburgh Review,” July 1837); Dr. W. Windelbrand, “History of Philosophy,” New York, 1893, translated by Jas. H. Tufts, pp. 380–388; Dr. Friedrich Ueberweg, “History of Philosophy,” translated by Geo. S. Morris, New York, 1885, Vol. II. pp. 33–38; Leopold Von Ranke, “History of England,” Vol. I. pp. 455–459, Vol. III. p. 383; William Whewell, “The Philosophy of the Inductive Sciences,” London 1840, Vol. II. pp. 388–413; “Critical Dictionary of English Literature,” S. Austin Allibone, Philad. 1888, Vol. I. pp. 89–96; “Catalogue Général des livres imprimés de la Bibliot. Nation.,” Paris, 1901, Vol. VI. pp. 236–253; Chas. Wells Moulton, “Library of Literary Criticism,” Vol. I. pp. 638–669; “The Philosophical Works of Francis Bacon,” by John M. Robertson, New York, 1905; “The Grammar of Science,” by Karl Pearson, London, 1900, pp. 506–508; “Encycl. Britann.,” Edinburgh, 1842, seventh edition, Vol. I. as per Index pages 16–17 and at “Dissertation First,” pp. 32–40; “Essai Theorique ... des connaissances humaines,” par G. Tiberghien, Bruxelles, 1844, Vol. II. pp. 409–419; Geo Miller, “History Philosophically Illustrated,” London, 1849, Vol. II. p. 430; “Francis Bacon,” by B. G. Lovejoy, London, 1888; “His Life and Character,” pp. 1–188, and “His Essays and Extracts,” pp. 19–277; “Francis Bacon,” by Kuno Fisher, London, 1857; “Encycl. Brit.” ninth edition, Vol. III. pp. 200–218; Bacon’s “Novum Organum,” by Thomas Fowler, New York, 1881, and Oxford, 1889; “Histoire des Sciences,” par F. L. M. Maupied, Paris, 1847, Vol. II. pp. 252–281, for “Enumeration Méthodique--Eléments--Analyse--des ouvrages de Francis Bacon”; “Library of Useful Knowledge,” for account of Lord Bacon’s “Novum Organum”; “Epitome of Electricity and Galvanism,” Philad., 1809, pp. xvi, 105; Whewell, “History of the Inductive Sciences,” Vol. I. pp. 339, 385, 494, 530; Van Swinden, “Recueil de Mémoires ...” La Haye, 1784, Vol. II. pp. 355, 364, 369–370; and, for an exhaustive biographical account of Francis Bacon, consult the “English Cyclopædia,” Vol. I. pp. 470–476. It is stated by C. R. Weld in his “History,” Vol. I. p. 64, that the establishment of the Royal Society was much accelerated by the writings of Lord Bacon (Buchmeri, “Acad. Nat. curi. Hist.”).

=A.D. 1620–1655.=--Bergerac (Savinien Cyrano de), a very witty French writer, is the author of a fragment on physics, as well as of a curious philosophical romance, “Histoire comique des états et empires de la lune,” a translation from which latter is here given, as in a measure suggesting the phonograph: “On opening the box, I found a number of metallic springs and a quantity of machinery resembling the interior of our clocks. It was, in truth, to me a book, indeed, a miraculous book, for it had neither leaves nor characters, and to read it, one had no need of eyes, the ears alone answering the purpose. It was only necessary to start the little machine, whence would soon come all the distinct and different sounds common to the human voice.”

Another translation reads as follows: “On opening the box I found inside a concern of metal, something like one of our watches, full of curious little springs and minute machinery. It was really a book, but a wonderful book that has no leaves or letters; a book, for the understanding of which the eyes are of no use--only the ears are necessary. When any one wishes to read, he winds up the machine with its great number of nerves of all kinds, and turns the pointer to the chapter he wishes to hear, when there come out, as if from the mouth of a man or of an instrument of music, the distinct and various sounds which serve the Great Lunarians as the expression of language.”

As has been said by one of his biographers, “amid the extravagance of some of his works, Bergerac nevertheless exhibited a pretty good acquaintance with the philosophy of Descartes.”

REFERENCES.--Article “Aeronautics” in the “Encycl. Brit.,” 1853, Vol. II. p. 168; Larousse, “Dict.,” Vol. V. p. 730.

=A.D. 1621.=--Helmont (Jean Baptiste van), famous Belgian scientist, publishes in Paris his “De Magnetica,” etc. (on the magnetic cure of wounds). His theories on magnetism greatly resemble those of Paracelsus, but in his treatment of them he shows himself much superior to the Swiss alchemist, whom Dr. Hœfer says he took as his model. “Magnetism,” Van Helmont observes, “is an unknown property of a heavenly nature, very much resembling the stars, and not at all impeded by any boundaries of space or time.... Every created being possesses his own celestial power and is closely allied with heaven ... the spirit is everywhere diffused; and the spirit is the medium of magnetism ... it is not the spirits of heaven and of hell which are masters over physical nature, but the soul and spirit of man which are concealed in him as the fire is concealed in the flint.”

The above-named work of Van Helmont was “translated, illustrated and ampliated,” in 1650 by Dr. Walter Charleton, physician in ordinary to King Charles I, under the name of “A Ternary of Paradoxes.” From its interesting contents, we make the following extracts:

Page 10. “A loadstone placed upon a small trencher of wood, floating on water, does instantly in one determinate point australize, and in the other septentrionate ... all which various and admirable effects of the loadstone, thou maiest, if thy judgement relish them, finde made good by multiplyed observations, by William Gilbert, not many yeers past, a physician in London, in his book, ‘De Magnete’: of which subject no man ever writ more judiciously or experimentally: and by whose industry the variation of the compasse may be restored....”

Page 12. “There is a book imprinted at Franekera, in the year 1611, by Vldericus Dominicus Balck, of the Lamp of Life. In which you shall finde, out of Paracelsus, the true magneticall cure of most diseases, as of the Dropsie, Gout, Jaundice, etc.”

Page 15. “Doth not the needle of the Mariner’s Compasse, through a firme glasse, closely sealed up with melted soder (in which there can be no pore or crany discovered) steer it self to the Artick pole? ... wherefore the same numericall accident streaming in one continued radius from the loadstone into the aer, passes through the glasse, and perhaps goes as farre as to touch the pole it self....”

Page 38. “Wherefore the loadstone owes its polarity to a natural inhærent faculty, flowing from its owne seminall entity, and not to any forreigne alliciency, or attractive influx transmitted from the north star. But that otherwise the loadstone may, by its own instinct, be elevated towards the Zenith, we have upon ocular demonstration found it true, by a certain instrument invented by Guilielme Guilbert (the glory of which excellent invention Ludovicus Fonseca hath lately endeavoured to ravish) ... which by the spontaneous elevation of the loadstone in a brasse ring suspended by a thread or small wier, shews not only the latitude but also the altitude of the pole, in all places of the earth.”

Page 39. “... the loadstone is endued with a domestick pilot, a directive faculty, which guides it to some determinate place, but is not at all attracted by the pole.”

Page 40. “The loadstone onely by the affriction of Garlick, amits its verticity, and neglects the pole, conserving to it self, in the meane time, its peculiar forme, materiall constitution, and all other dependent proprieties. The reason, because Garlick is the loadstone’s proper Opium, and by it that spirituall sensation in the magnet is consopited and layd asleep.... Verily, that alliciency of the pole must be extreame weake and of inconsiderable energy, which passing through so many and so immense orbes of heaven, and striking through great and firme buildings, and thick walls, cannot yet be of power sufficient to pierce the thin juice of Garlick or the fume of Mercury....”

Page 42. “There is therefore inhærent in the magnet an influentiall virtue, which, being not obliged to the propinquinty or comtiguous admotion of its object, is after the nobler names of coelestiall influences, freely and without interruption or languor transmitted so farre as to the pole it self: since there is a spontaneous eradiation, or emission of atomicall radii from the body of the magnet to the pole.”

Page 74. “That the magnetisme of the loadstone and other inanimate creatures is performed by a certaine naturall sensation, the immediate anthrix of all sympathy, is a truth unquestionable.”

Page 75. “For by one phansy it is directed to iron, and by another to the pole ... the phansy of amber delights to allect strawes, chaffe, and other festucous bodies; by an attraction, we confesse, observe obscure and weake enough, yet sufficiently manifest and strong to attest an Electricity or attractive signature....”

REFERENCES.--“Dict. of Nat. Biog.,” Vol. X. pp. 116–119, containing a full list of Charleton’s works; Thomson, “Hist. of the Roy. Soc.,” 1812, p. 3; Munk, “Coll. of Phys.,” 1878, Vol. I. p. 390; “Journal des Savants” for February and March 1850, June 1851; Mme. Blavatsky, “Isis Unveiled,” Vol. I. p. 170; Eloy, “Dict. Hist. de la Médecine,” Vol. II. pp. 478–482; “Dict. Hist. de la Médecine,” par. J. E. Dezeimers, Paris, 1839, Vol. III. pp. 97–104; “Ency. Brit.,” ninth edition, Vol. XI. p. 638; “History and Heroes of the Art of Medicine,” by J. Rutherfurd Russell, London, 1861, pp. 197–204; Larousse, “Dict. Univ.,” Vol. IX. p. 158; Van Swinden, “Recueil,” La Haye, 1784, Vol. II. pp. 351–352, 361–363; Joseph Ennemoser, “The History of Magic,” London, 1854, Vol. II. pp. 242–253.

=A.D. 1623.=--Hervart--Heroart--Herwart--Hörwarth (Joannes Fridericus), son of Johann Georg Hervart ab Hohenburg, the well-known scientist (1554–1622), who during forty-five years occupied the post of Bavarian Chancellor under three reigning princes--completes his father’s work entitled “Admiranda ethnicæ theologiæ ...” which, Larousse says (“Dictionnaire Universel,” Vol. IX. p. 250), was published at Munich, 1624, and in which he demonstrates that the earlier Egyptian divinities were natural phenomena personified and adored under symbolic names. Michaud, who reiterates this (“Biographie Universelle,” Vol. XIX. p. 364), speaks of the edition which appeared at Munich in 1626, and he also states that, at the end of the latter, will be found “Exacta temporum ... chronologiæ vulgaris errores,” which is the continuation of the “Chronologia Nova,” left unfinished by the Bavarian Chancellor. This is, in fact, so mentioned in the only copy possessed by the British Museum, which was published by J. F. Hervart ab Hohenburg at Ingolstadii, 1623, and of which the title reads: “Admiranda Ethnicæ Theologiæ Mysteria propalata. Ubi lapidem magnetem antiquissimis passim nationibus pro Deo-deocultum: et artem qua navigationes magneticæ per universum orbem instituerentur....”

Libri’s “Catalogue,” 1861, Part I. p. 405, No. 3703, has the following entry: “Admiranda Ethnicæ ... ubi Lapidem Magnetem antiquissimis Nationibus pro Deo cultum commonstratur ...” Ingolstadii, 1623. The work itself endeavours to prove that the loadstone’s properties were well known to the ancients.

The “General Biographical Dictionary” of Alexander Chalmers, London, 1814, Vol. XVII. p. 426, makes following entry: “Herwart (or Hervart) John George, Chancellor of Bavaria at the beginning of the seventeenth century, published some works wherein his learning was more displayed than his judgment, in supporting the most extravagant systems. Two of his works are: ‘Chronologia nova et vera,’ in two parts, 1622 and 1626, and ‘Admiranda Ethnicæ Theologicæ Mysteria propalata, de antiquissima veterum nationum superstitione, qua lapis Magnes pro Deo habitus colebatur,’ Monach, 1626, quarto. It was here asserted that the ancient Egyptians worshipped the magnet,” etc. (see Deveria, under B.C. 321).

REFERENCES.--Allusions to Hervart, made at p. 546, Vol. XXIV. of Dr. Hœfer’s 1861 “Nouvelle Biographie Générale,” or at p. 546, Vol. XXVIII of the 1858 edition, and also at p. 163, Vol. II of the “Bibliographie Générale de l’Astronomie,” by Houzeau et Lancaster, Bruxelles, 1882. Likewise Chr. G. Jöcher, “Compendiöses Gelehrten Lexicon,” Leipzig, 1787, Vol. II. p. 1969, and “A New General Biogr. Dict.,” London, 1850, Vol. VIII. p. 304.

=A.D. 1624.=--Gunter (Edmund), professor of astronomy at Gresham College, publishes his work “Of the Sector, Cross-Staff, and other Instruments,” at Chap. V of the second book of which he gives the result of the eight observations he made on the variation of the variation “in various parts of the ground” at Limehouse on the 13th of June, 1622. His observations of the declination, as given by Prof. Gellibrand, are detailed at Chap. I of Walker’s “Ter. and Cos. Mag.,” Cambridge, 1866.

REFERENCES.--De La Rive, “Electricity,” etc., Vol. I. p. 165; Poggendorff, “Geschichte der Physik,” Leipzig, 1879, p. 275.

=A.D. 1625.=--Carpenter (Nathaniel), Dean of Ireland, well-known mathematician, publishes at Oxford, “Geography delineated forth in two bookes, containing the sphæricall and topicall parts thereof,” wherein he thus alludes to Dr. Gilbert’s “De Magnete”: “Magneticall proprieties, I find in ancient writers, as little knowne as their causes; and if any matter herein were broached, it was merely conjectural, and depending on no certain demonstration; neither had we any certain or satisfactory knowledge of the thing vntill such time as it pleased God to raise vp one of our countrymen, D. Gilbert, who, to his euerlasting praise, hath trodden out a new path to Philosophie, and on the Loadstone, erected a large Trophie to commend him to posterity. This famous Doctor being as pregnant in witty apprehension as diligent in curious search of naturall causes, after many experiments and long enquiry, found the causes of most magneticall motions and proprieties hid in the magneticall temper and constitution of the Earth, and that the earth it selfe was a meere magneticall body challenging all those proprieties, and more than haue expressed themselves in the Loadstone; which opinion of his was no sooner broached than it was embraced, and wel-commed by many prime wits as well English as Forraine. Insomuch that it hath of late taken large root and gotten much ground of our vulgar Philosophie.”

REFERENCES.--“Nature,” September 26, 1901; “Dict. of Nat. Biogr.,” Vol. IX. pp. 161–162; Larousse, “Dict.,” Vol. IV. p. 438; Prince’s “Worthies” (1810), pp. 173–175, 603.

=A.D. 1625.=--Naudé (Gabriel), a celebrated French savant and one of the most learned of his day, also physician to King Louis XIII, and an intimate friend of Gassendi, is the author of “Apologie pour tous,” etc. (“Apology for great men falsely accused of magic”), of which other editions appeared in 1652, 1669 and 1712. The magico-theosophical philosophy, as Madame Blavatsky expresses it, is fully indicated in his work, and he proved to be the warmest defender of the doctrines of occult magnetism, of which he was one of the first propounders.

REFERENCES.--“Biog. Générale,” Vol. XXXVII. pp. 514–518; P. Hallé, “Gab. Naudé Elogium”; N. Sanson, “Hist. Chr. d’Abbeville,” 1653; Sainte Beuve, “Portraits Littéraires,” 1855; Alf. Franklin, “Hist. de la Biblioth. Mazarine,” 1860.

=A.D. 1627.=--Hakewill (George), Archdeacon of Surrey, publishes at Oxford, England, the first edition of “An Apologie or Declaration of the Power and Providence of God,” the tenth chapter, fourth section of the third book of which alludes to the use of the “mariner’s compass or sea-card, as also of another excellent invention sayd to be lately found out upon the loadstone.” As the reviewer justly observes: “While perusing his description one can hardly imagine that the writer had not in his mind’s eye one of our modern telegraphic instruments ... and it will be seen that the date at which his work is written was nearly two hundred years prior to the first attempt made to communicate at a distance by means of magnetic needles.”

Hakewill alludes (“Apologie,” 1635, lib. ii. p. 97) to Hipparchus--Abraxis--“who reports that, in his time, the starre commonly called the Polar Starre, which is in the tayle of the lesser Beare, was twelve degrees and two-fifths distant from the Pole of the Æquator. This starre, from age to age, hath insensibly still crept nearer to the pole so that at this present it is not past three degrees distant from the pole of the Æquator. When this starre then shall come to touch the Pole, there being no farther place left for it to go forward (which may well enough come to pass with five or six hundred yeares) it is likely that then there shall be a great change of things, and that this time is the period which God hath prefixed to Nature” (see Morell’s “Elem. ... Phil. and Sc.,” London, 1827, pp. 116–119 et seq.).

Mention of the star in the tail of Ursa Major is made by Gilbert, (“De Magnete”),[41] in connection (1) with Marcilius Ficinus, who, says he, seeks in that constellation the cause of the magnetic direction, as he believes that in the loadstone the potency of Ursa prevails and hence is transferred to the iron; (2) with Cardan, who assigns the cause of variation to its rising, for he thinks variation is always to be relied upon at the rising of the star; (3) with Lucas Gauricus, who holds that the loadstone beneath the tail of Ursa Major is ruled by the planets Saturn and Mars; (4) with Gaudentius Merula, who believes that the loadstone draws iron and makes it point North because it is of a higher order than is the iron in the Bear.

REFERENCES.--Larousse, “Dict. Univ.,” Vol. IX. p. 26; “Dict. of Nat. Biog.,” Vol. XXIV. pp. 6–8; Walton and Cotton, “Complete Angler,” New York and London, 1847, Part I. p. 118.

=A.D. 1628.=--Leurechon (Jean), a student belonging to the Order of Jesuits (1591–1670), who became the confessor of Charles IV of Lorraine, publishes, under the name H. Van Etten, “La Récréation Mathématique,” carefully revised editions of which were made by Claude Mydorge and Denis Henrion in 1630, 1638 and 1661. In these, Leurechon alludes to the reported transmission of intelligence by the agency of a magnet or other like stone, saying: “The invention is beautiful, but I do not think there can be found in the world a magnet that has such virtue.”

REFERENCES.--Georges Maupin, “Opinions touchant la mathématique,” Paris, 1898, pp. 20–24; Larousse, “Dict.,” Vol. X. p. 436; “Sc. Am. Suppl.,” Nos. 56, p. 881, and 384, p. 6125.

The curious title-page of the English version of Leurechon’s work, published by T. Cotes in 1633, merits reproduction: “Mathematicall Recreations, or a Collection of sundrie Problemes, extracted out of the Ancient and Moderne Philosophers, as secrets in nature, and experiments in Arithmeticke, Geometrie, Cosmographie, Horologographie, Astronomie, Navigation, Musicke, Optickes, Chimestrie, Waterworkes, Fireworks, etc., Fit for Schollers, Students, and Gentlemen ... lately compiled in French by Henry Van Hetten. And now delivered in the English tongue.”

Claude Mydorge, as stated in the “Biog. Gén.,” Vol. XXXVII. p. 87, was a French scientist (1585–1647), a very close friend of Descartes, and, according to Baillet, was next to Vieta, the foremost mathematician of his day. The second edition of his “Examen du livre des Récréations Mathématiques (du Père Leurechon),” contains notes of Denis Henrion following the observations of Père Mersenne in “Universæ ...” Paris, 1639 (see Bouillet, “Vie de Descartes,” Vol. I. pp. 36–37, 149–150, and Vol. II. pp. 43, 76, 78, 325).

Denis Henrion was also a French mathematician, who died about 1640. He was the author of many very meritorious papers, notably of a “Traité des Globes et de leurs usages,” 1618, translated from the Latin of Robert Hues, 1593, 1594 (Larousse, “Dict. Univ.,” Vol. IX. p. 192).

=A.D. 1629.=--Cabæus--Cabeo (Nicolaus), a learned Jesuit of Ferrara, describes (“Philosophia Magnetica”)[42] numerous experiments made by him to ascertain the possibility of two persons communicating intelligence by means of magnetized needles.

Cabæus was the first to observe electrical repulsion, and he thus announces his discovery in the tenth chapter of the above-named work: “Magnetic attractions and repulsions are physical actions which take place through the instrumentality of a certain quality of the intermediate space, said quality extending from the influencing to the influenced body.... Bodies are not moved by sympathy or antipathy, unless it be by means of certain forces which are uniformly diffused. When these forces reach a body that is suitable they produce changes in it, but they do not sensibly affect the intermediate space nor the non-kindred bodies close by it....”

The “Philosophia Magnetica” is the second Latin book published on electricity, Gilbert’s “De Magnete” being the first.

REFERENCES.--Becquerel, “Résumé,” Chap. III; Stuello, “Bibl. Scrip. S. J.,” Rome, 1676; Francisco de Lanis, “Magist. nat. et artis,” 1684; L. L. de Vallemont, “Description de l’aimant,” 1692, pp. 167, 170; Dechales C. F. Milliet, “Cursus seu Mundus Mathem.,” 1674, 1690.

=A.D. 1632.=--Sarpi (Pietro)--Fra Paolo Sarpi--Father Paul--Paulus Venetus--Paolo Sarpi Veneto (b. 1552, d. 1623), who was the author of the celebrated history of the Council of Trent (“the rarest piece of history the world ever saw”) is referred to by Gilbert in “De Magnete,” Book I. chap. i. Therein, he says that Baptista Porta, who has made the seventh book of his “Magia Naturalis” a very storehouse and repertory of magnetic wonders, knows little about the movements of the loadstone and never has seen much of them, and that a great deal of what he has learned about its obvious properties, either through Messer Paolo, the Venetian, or through his own studies, is not very accurately noted and observed.

In the introduction to the 1658 edition of his “Natural Magick,” Porta admits that he gained some knowledge of Sarpi, who, says he, is of all men he ever knew the most learned and skilful and the ornament and splendour not only of Venice or of Italy, but of the entire world. Bertelli refers (“Memor. sopra P. Peregrino,” p. 24, note) to P. Garbio’s “Annali di Serviti,” Lucca, 1721, Vol. II. pp. 263, 272, 274, and to Fra Fulgenzio Micanzio’s “Life of Sarpi,” Helmstat--Verona, 1750, in which it is stated that not only Porta but likewise a celebrated ultramontane studied magnetism under him. Garbio asks: “Could this ultramontane be Gilbert of Colchester?”

By Griselini (“Vita de Fra P. Sarpi”--memoria anecdote--Lausanne, 1760), Paolo is said to have written a treatise on the magnet and to have therein recorded many observations, including the earliest mention that magnetic properties are destroyed by fire.

Bertelli--whose afore-named memoir we must confine ourselves to, as it is more satisfactory than are the accounts elsewhere given--makes mention that he has had in his possession, by courtesy of Sig. Giuseppe Valentinelli, the Royal Librarian of the Marciana at Venice, copy of a manuscript (Cod. CXXIX, classe 2, MS. Ital.) containing a brief comparison of Sarpi’s magnetic researches with those of Musschenbroek. This manuscript is again alluded to by Bertelli (Memor., p. 88) wherein it is said that lines 5–38 of the first column, p. 170, are headed “Observations of F.P.S. on the loadstone, collated with P. Musschenbroek’s Researches,” and embrace five paragraphs translated as follows:

1. The author had first tried the action of one magnet on another without entering into the question of calculation, but modern authors have, in view of the observations made, endeavoured to discover a method of computing magnetic forces in any proportion to the distances, and in the same better regulated systems they have discovered the cause to be uncertain (or varying) owing to the contemporaneous action of magnetic repulsion.

2. He was acquainted with the well-known action of the magnet on iron, but he understood--as even at this day some understand--that it was caused by the atmosphere. New experiments have made us seriously doubt this. He did not pay attention to the proportion of the magnetic forces as compared with the distances of iron, to the discovery of which the efforts of present philosophers are directed but in vain. He saw, however, that the facility or difficulty of attraction depends upon the size of the iron (maximum and minimum).

3. He was not ignorant of the direction of the magnet and of iron rubbed with the magnet towards certain quarters of the sky when he mentions the new discovery of the poles in the magnet, and the variation of the magnetized needle, from the Northern or the Southern quarters, but he did not know a greater number than two poles found in the magnet, the variation of the declination, or, I should rather say, the uncertainty of the variation and the different inclinations of the needle at different places on the earth.

4. Almost all the experiments referred to by Academies, with reference to the action of one piece of iron on another piece of iron, magnetized and not magnetized, and with regard to the changes of forces which arise from the various inflections of iron, have been sufficiently sketched out by F. P. S.

5. The magnetic effects acquired by an old piece of iron continually exposed to the air have also been alluded to. Now, however, natural philosophers have observed that this iron exposed for a length of time in the magnetic meridian points with greater readiness to the above-mentioned quarters. They have, moreover, ascertained that iron when heated and afterwards cooled in water is more sensitive to magnetization: which is directly opposed to the opinion of F. P. S.

Bertelli further remarks that, from information given in the manuscript, it is seen that Sarpi was at that time acquainted with the greater number of the magnetic phenomena referred to by Porta, and developed by Gilbert, viz.:

1. The reciprocal action of magnets;

2. The action of magnets on iron;

3. The manifestation of magnetic activity about the poles (sphere of action or field of force);

4. The Maximum and the Minimum of the attractive force of magnets on iron, according to the size of the latter;

5. The inversion of polarity which may arise in the magnetization of needles--(but not the corresponding poles--the magnetic variation or declination--Petrus Peregrinus, A.D. 1269--yet not the variation of the variation--Henry Gellibrand, A.D. 1635--nor the dip or inclination--Robert Norman, A.D. 1576).

6. The magnetic properties acquired by iron constantly exposed to the air.

After detailing the observations of Giulio Cesare Moderati, Filippo Costa (Costæus) of Mantua, Ulysses Aldrovandi, Francesco Acoromboni, Luigi Matteini, Father Garzoni and Father Cabæus concerning the magnetized ironwork of the belfry of the church of St. Augustine at Arimini (the parochial church of St. John the Baptist, which at that time, 1586, belonged to the monks of St. Augustine) and relative to the iron rail in the belfry of the tower of St. Laurence at Rome, Bertelli says: “From all that precedes, we gather at all events, that the fact of the spontaneous magnetization of iron was well known in Italy before Sarpi, Porta and Gilbert. This, Gilbert, and still better Cabæus, explained as the influence of terrestrial magnetism. However, with regard to the observations of the needle’s deviation made by Father Garzoni at Rome, we can, without having attributed it, as does Cabæus, to the magnetization of pieces of iron concealed in its wall, explain it, as is done in the new and important experiments of the illustrious professor Silvestro Gherardi, who attributes it to the magnetic polarity of the Mattoni [bricks] in the structure itself.”

It is said by Humboldt (“Cosmos,” 1849, Vol. II. p. 718, note) that this observation, the first of the kind, was made on the tower of the church of the Augustines at Mantua (Mantova) and that Grimaldi and Gassendi were acquainted with similar instances (instancing the cross of the church of St. Jean, at Aix, in Provence), in geographical latitudes where the inclination of the magnetic needle is very considerable. Some writers give Gassendi’s observation as occurring during 1632 (see Rohaulti, “Physica,” 1718, Par. III. cap. 8, p. 399; or, Rohault’s “System of Nat. Phil.,” 1728, p. 176).

“As the iron cross of an hundred weight upon the Church of St. John in Ariminum, or that load-stoned iron of Cæsar Moderatus, set down by Aldrovandus” (Sir Thomas Browne, “Pseudodoxia Epidemica,” 1658, p. 66).

Consult “Lettera dell’Eccel. Cavallara.,” Mantova, 1586, for a detailed account of this discovery, made January 6, of the last-named year. The iron rod supported a brick ornament in the form of an acorn, and stood on a pyramid at the summit of the belfry of the church of St. Augustine (Cabæus, “Philos. Magn.,” p. 62; “Ulysses Aldrovandi, Patr. Bonon ... Barthol. Ambros ...” Lib. i, cap. 6, p. 134).

For the account given by Aldrovandi of the Arimini observation and for references to Browne’s “Pseudodoxia Epidemica,” as well as to Boyle’s “Experiments,” see p. 53 of the valuable “Notes on the ‘De Magnete’ of Dr. William Gilbert,” by Silvanus P. Thompson, attached to the English translation of the original 1600 edition, which was so attractively produced by the Gilbert Club during the year 1900. Dr. Thompson further gives, at the page following (54), additional references to examples of iron acquiring strong permanent magnetism from the earth.

REFERENCES.--Biography of Sarpi in the “Encycl. Brit.,” ninth edition, Vol. XXI. pp. 311–313; F. Micanzio, “Vita de F. P. Sarpi,” Verona, 1750; Rev. Alex. Robertson, “Fra Paolo Sarpi--the greatest of the Venetians,” 1894; Hallam, “Intro. to Lit.,” 1839, Vol. II. p. 464; U. Aldrovandi, “Musæum Metallicum,” 1648, p. 134; Tiraboschi, “Storia della Lettera,” Modena, 1794, Vol. VI. part ii. p. 506; Sarpi’s Complete Works, first published at Helmstat, 1750; Fabroni, “Vitæ Italorum,” Pisa, 1798; Giovini, “Vita,” Brussels, 1836; “Engl. Cycl.,” Biography, Vol. IV. pp. 695–697; Larousse, “Dict. Univ.” Vol. XIV. pp. 230–231; “History of the reign of Charles the Fifth,” by Wm. Robertson and Wm. H. Prescott, Philadelphia, 1883, Vol. III. p. 68; “Dict. Hist. de la Médecine,” N. F. J. Eloy, Mons, 1778, Vol. IV. pp. 180–181; “The Atlantic Monthly,” New York, January and February, 1904, wherein the author, Andrew D. White, ranks Sarpi with Machiavelli and Galileo; Libri, “Hist. des Sc. Mathém.” Paris, 1838, Vol. IV. p. 214, note.

=A.D. 1632.=--Gassendi (Pierre), an eminent French savant, professor at the Royal College of France, “ranked by Barrow among the most eminent mathematicians of the age, and mentioned with Galileo, Gilbert and Descartes,” discovers that a part of the iron cross of the Church of St. Jean at Aix possesses all the properties of a loadstone after being struck by lightning and lying in one position a certain length of time. Gilbert mentions, “De Magnete,” 1600, Book III. chap. xii.) that the fact of magnetism being imparted to an iron bar by the earth was first ascertained by examining the rod upon the tower of the church of St. Augustine at Arimini (Sir Thomas Browne, “Pseud. Epidemica,” London, 1650, p. 48; U. Aldrovandi, “Musæum Metallicum,” Milan, 1648, p. 134).

In the “Vie de Pierre Gassendi,” par le Père Bougerel de l’Oratoire, Paris, 1737, p. 14, it is related that during the month of September 1621, while promenading about three leagues’ distance from Aix in a village named Peynier, he observed a light in the heavens to which he gave the name of aurora borealis, as much on account of its location as by reason of its resemblance to the light which precedes the rising of the sun.

From the “History of the Royal Society,” by C. R. Weld, 1848, Vol. II. p. 430, is taken the following, communicated by Humboldt:

“The movement of the magnetic lines, the first recognition of which is usually ascribed to Gassendi, was not even yet conjectured by William Gilbert; but, at an early period, Acosta, ‘from the information of Portuguese navigators,’ assumed four lines of no declination upon the surface of the globe.... In the remarkable map of America appended to the Roman edition of the Geography of Ptolemy in 1508, we find, to the north of Gruentland (Greenland), a part of Asia represented and the magnetic pole marked as an insular mountain. Martin Cortez, in the ‘Breve Compendio de la Sphera’ (1545), and Livio Sanuto, in the ‘Geographia di Tolomeo’ (1588), place it more to the south. Sanuto entertained a prejudice, which, strange to say, has existed in later times, that a man who should be so fortunate as to reach the magnetic pole (Il calamitico) would then experience alcun miracoloso stupendo effecto” (“Cosmos,” translated under the superintendence of Col. Sabine, Vol. II. p. 280). In a footnote to the Otté translation of Humboldt, 1859, Vol. V. p. 58, it is stated that calamitico was the name given to the instruments in consequence of the first needles for the compass having been made in the shape of a frog.

In Gilbert’s “De Magnete,” allusion is made to Martinus Cortez, Book I. chap. i., also Book III. chap. i. and Book IV. chap. i.,[43] and to Livio Sanuto in Book I. chap. i., also in Book IV. chaps. i. and ix. In these several passages, Gilbert tells us that Martinus Cortez holds the loadstone’s seat of attraction to be beyond the poles, and he states the views of other writers in this respect, citing more particularly T. de Bessard (author of “Le Dialogue de la Longitude”), Jacobus Servertius (who wrote “De Orbis Catoptrici”), as well as Robert Norman, Franciscus Maurolycus, Marsilio Ficino, Cardan, Scaliger, Costa and Petrus Peregrinus (M. J. Klaproth, “Lettre à M. le Baron de Humboldt,” Paris, 1834, pp. 16–17, 37).

REFERENCES.--Enfield, “Hist. Phil.,” Vol. III. p. 430; “Le Cosmos” for May and June 1859, containing a very interesting series entitled, “Les Armées Météores”; Lardner, Vol. II. p. 113; Humboldt, “Cosmos,” 1859–1860, Vol. II. p. 335, and Vol. V. pp. 146–153; Julius Cæsar at A.D. 1590; Houzeau et Lancaster, Vol. II. p. 146; “Mém. de l’Acad. Royale des Sciences,” Vol. X. p. 737; “Phil. Hist. and Memoirs of the Royal Acad. of Sc.,” Vol. II. p. 281; “Geschichte der Mathematik,” Vol. IV. p. 474.

=A.D. 1632.=--Galileo (Galileo Galilei), Italian philosopher and mathematician, publishes his celebrated “Dialogo sopra i due massimi sistemi del mondo tolemaico e copernicano,” 4to, Fiorenza, from p. 88 of which is extracted the following passage:

Sagredus: “You remind me of a man who offered to sell me a secret for permitting one to speak, through the attraction of a certain magnet needle, to someone distant two or three thousand miles, and I said to him that I would be willing to purchase it, but that I would like to witness a trial of it, and that it would please me to test it, I being in one room and he being in another. He told me that, at such a short distance, the action could not be witnessed to advantage; so I sent him away and said that I could not just then go to Egypt or Muscovy to see his experiment, but if he would go there himself I would stay and attend to the rest in Venice.”

This Sagredus (Iohannes Franciscus), or Sagredo (Giovanni Francisco), besides being “a great magneticall man,” was a noble Venetian, even a doge, and had represented his country as ambassador at several courts. We read in Mr. Conrad W. Cooke’s very able article on William Gilbert of Colchester, originally printed in London “Engineering,” that this same Sagredus was the intimate friend of Galileo, and that, together with the powerful Sarpi, he used the whole might of his name and influence to protect the great philosopher and mathematician from the attacks of the clerical party. Pietro Sarpi, otherwise known as Father Paul, was, as already shown, a most illustrious Venetian scholar, who attained great proficiency in the medical and physiological sciences as well as in mathematics and in natural philosophy. Sagredus made several meritorious researches in magnetism, and, while on a voyage to Aleppo, ascertained the declination of the magnetic needle at that place. As a tribute to the scientific attainments of Sagredus, Galileo gave his name to one of the characters in his “Systema Cosmicum,” and many references to the work by William Gilbert are put into the mouth of Sagredus.

In further illustration of Galileo’s appreciation of Gilbert, the following is quoted from the great astronomer’s own writing: “I extremely admire and envy the author of ‘De Magnete.’ I think him worthy of the greatest praise for the many new and true observations which he has made, to the disgrace of so many vain and fabling authors, who write not from their own knowledge only, but repeat everything they hear from the foolish and vulgar, without attempting to satisfy themselves of the same by experience; perhaps that they may not diminish the size of their books” (Drinkwater’s “Life of Galileo”).

Galileo had also published, in 1630, the first edition of his “I discorsi e demonstrazioni ...” which Lagrange considers to be Galileo’s most substantial title to scientific glory.

REFERENCES.--Galileo’s Biography in “Engl. Cycl.,” Vol. III. pp. 13–17; Miller, “Hist. Phil. Illust.,” London, 1849, Vol. III. p. 203, note; Nelli, “Vita,” 1793; Libri, “Hist. des Sc. Math.,” Paris, 1838, Vol. IV. pp. 157–294, 473–484; Houzeau et Lancaster, “Bibliog. Générale,” Vol. I. part i. pp. 655–657 for an analyzation of the works of Galileo, also Vol. II. pp. 137–145, 1576–1578; Wm. Whewell, “Phil. of the Ind. Sc.,” London, 1840, Vol. II. pp. 379–383; Guillaume Libri, “Histoire des Sc. Math.,” Halle, 1865, Vol. IV. pp. 157–302, and the notes; “Journal des Savants” for September and October 1840, for March and April 1841, for July to November 1858, for September 1868 and for October 1877; “Geschichte der Mathem.,” Vol. IV. pp. 4, 173, etc.; Larousse, “Dict.,” Vol. VIII. p. 954; “La Grande Encycl.,” Vol. XVIII. pp. 383–385; “Biog. Gén.,” Vol. XI. pp. 252–267; Fabroni (A.), “Vitæ Italorum,” 1778–1805, also “Elogi d’Illustri Italiani,” 1786–1789; likewise the very numerous entries concerning Galileo’s history, his Opponents, Supporters and School, which appear at pp. 331–357, Part I. of Libri’s “Catalogue,” published in 1861. Consult also “Galileo,” by Ed. S. Holden, in the “Popular Sc. Monthly” for January, February, May and June 1905; “Bibliot. Brit.,” Vol. XVI. N.S., 1821, pp. 3–21, 79–100, for an account of the life of Galileo by M. G. B. Clément de Nelli; “Journal des Sçavans,” Vol. LXX. for 1721, p. 350 in his “Saggiotore”; “Imperial Dictionary of Universal Biography,” published by Wm. McKenzie, London, pp. 536–539, giving an account of Galileo’s other discoveries.

=A.D. 1635.=--Delambre (J. B. J.) (1749–1822), professor of astronomy at the Royal College of France, refers (Vol. II. p. 545 of his “Histoire de l’Astronomie Ancienne,” 1817) to the mention made in “Procli Diadochi Paraphrasis Ptolem.,” lib. iv. “de siderum effectionibus,” 1635, p. 20, of the notion long current, especially along the shores of the Mediterranean, “that if a magnetic rod be rubbed with an onion, or brought into contact with the emanations of the plant, the directive force will be diminished, while a compass thus treated would mislead the steersman.”

REFERENCES.--Humboldt, “Cosmos,” 1859, Vol. V. p. 156, also the entry at A.D. 1653. See likewise Whewell, “Hist. of the Ind. Sc.,” Vol. I. pp. 442, 443, 447, and the biography in the Supplement of the “English Cyclopædia,” pp. 539–541; “Journal des Savants,” for April 1828.

=A.D. 1635.=--Gellibrand (Henry), prominent English mathematician, professor of geometry and the successor of Edmund Gunter (A.D. 1624), in the chair of astronomy at Gresham College, publishes his discovery of the secular variation of the declination. The credit of this discovery has been by many given to John Mair. The diurnal and horary variation was found by Graham in 1722, and the annual variation was discovered by Cassini, 1782–1791.

Gellibrand’s discovery is published in a small quarto pamphlet entitled “A discourse mathematical on the variation of the magneticall needle--together with the admirable diminution lately discovered,” and is the result of his study of the observations made by Burrough and Gunter as well as of observations made by himself, all showing that the north-east of the needle was gradually moving to the westward.

Mention has already been made of the fact that the variation of the variation was at this period attracting the attention it deserved, and it is worth while giving here an account of the discovery in the author’s own words:

“Thus, hitherto, according to the Tenents of all our Magnetical Philosophers, we have supposed the variations of all particular places to continue one and the same. So that when a Seaman shall happly return to a place where formerly he found the same variation, he may hence conclude he is in the same former longitude. For it is the assertion of Mr. Dr. Gilbert’s Variatio unicuiusq; loci constans est, that is to say, the same place doth always retaine the same variation. Neither hath this assertion, for ought I ever heard, been questioned by any man. But most diligent magneticall observations have plainely offered violence to the same, and proved the contrary, namely, that the variation is accompanied with a variation.”

=A.D. 1637.=--Bond (Henry), Professor of Mathematics in London, and who appears in one of his treatises as “a famous teacher of the art of navigation,” is the author of the “Seaman’s Kalendar ... with a discovery of the ... secret of longitude ...” of which other editions appeared during 1640 and 1696.

This was followed by many papers on the variation (the most important of which are to be found in Phil. Trans. for 1668, 1672, 1673) and, during 1678 by “The Longitude not found, or an answer to a treatise written by H. B. ...” This treatise was in a sixty-five page pamphlet which had been issued by Mr. Bond’s father during 1676, under caption: “The Longitude Found; or a treatise shewing an easie and speedy way, as well by Night as by Day, to find the Longitude, having but the Latitude of the Place and the Inclination of the Magneticall Inclinatorie Needle ...” wherein he explains his discovery of the progress of the deviation of the compass and foretells the variations for London, 1663 to 1716. This treatise led to the controversy with Peter Blackborrow (Beckborrow), the title to whose published work reads: “The Longitude not found: or an answer to a treatise written by H. Bond, senior, shewing a way to find the longitude by the magnetical inclinatory needle: wherein is proved that the longitude is not nor cannot be found by the magnetic inclinatory needle.”

As Humboldt remarks, the resulting controversy, together with Acosta’s view that there were four lines of no variation which divided the earth’s surface, may, as already stated, have had some influence on the theory advanced, in 1683, by Edmund Halley, of four magnetic poles or points of convergence (“Cosmos,” 1859–1860, Vol. I. p. 193, note; Vol. II. pp. 280–281, note; Vol. V. p. 58; also Humboldt’s “Examen Critique de l’Histoire de la Géographie,” Vol. III. p. 60. See likewise the Phil. Trans. for October 19, 1668, p. 790, and for 1673, Vol. VIII. p. 6065, also following abridgments: Hutton, Vol. II. p. 78, and Lowthorp Vol. II. p. 610).

REFERENCES.--Walker, “Magnetism,” Chap. I; John Pell, “Letter of Remarks on Gellibrand’s Math. Disc.,” 1635; “Annales de Chimie et de Physique,” Mars 1902, Vol. XXV. pp. 289–307; Humboldt, “Cosmos,” 1859, Vol. V. pp. 61, 116; Whewell, “Hist. of the Ind. Sc.,” 1859, Vol. II. p. 219; G. Hellmann, “Neudrucke von Schriften,” No. 9; Baddam’s abridgments of the Phil. Trans., 1739, Vol. IV. p. 102.

=A.D. 1641.=--Wilkins (John), Bishop of Chester in the reign of Charles II, publishes the first edition of “Mercury, or the secret and swift messenger, showing how a man, with privacy and speed, may communicate his thoughts to a friend at any distance.”[44]

In the above, he thus alludes to the possibility of making a contrivance similar to our modern phonograph: “There is another experiment ... mentioned by Walchius, who thinks it possible so to contrive a trunk or hollow pipe that it shall preserve the voice entirely for certain hours or days, so that a man may send his words to a friend instead of his writing. There being always a certain space of intermission, for the passage of the voice, betwixt its going into these cavities and its coming out; he conceives that if both ends were seasonably stopped, while the sound was in the midst, it would continue there till it had some vent. Huic tubo verba nostra insusurremus, et cum probe munitur tabellario committamus, etc. When the friend to whom it is sent shall receive and open it, the words shall come out distinctly, and in the same order wherein they were spoken. From such a contrivance as this [saith the same author] did Albertus Magnus make his Image, and Friar Bacon his Brazen Head, to utter certain words.”

In the eighteenth chapter, he makes suggestions for “a language that may consist of only tunes and musical notes, without any articulate sound.”

He had previously described a novel mode of telegraphing by the use of only three torches (or lights), to designate the twenty-four letters of the alphabet. These letters were, according to the plan of Joachimus Fortius, to be placed in three classes of eight each. One torch indicated Class I, two torches Class II, three torches Class III, and the number of the letter was shown by the number of times a torch was elevated.

Bishop Wilkins also described a method of telegraphing by means of two lights attached to long poles, which, he says, “for its quickness and speed is much to be preferred before any of the rest.” To interpret messages at long distances, he suggested the use of the then newly invented telescope; which he called “Galileus his perspective.”

REFERENCES.--The third edition of above-named work, Chap. XVII. pp. 71, 72, also the fifth edition of Wilkin’s “Mathematical Magick,” London, 1707, Chap. XIII. pp. 147–150, “concerning several attempts of contriving a perpetual motion by magnetical virtues.” Likewise Whewell, “Hist. of the Ind. Sc.,” 1859, Vol. I. pp. 332, 395; Mendoza, “Tratado de Navegacion,” Vol. II. p. 72; Alex. Chalmers, “Gen. Biog. Dict.,” London, 1811, Vol. XXXII. pp. 74–82.

=A.D. 1641.=--Kircher (Athanasius), a German writer on physical and mathematical science (1601–1680), member of the Order of Jesuits, possessed of immense erudition and believing in the magnetism of all things, speaks in his “Magnes sive de arte magnetica” (Book II. pt. iv. chap. v.), of the recently advanced idea of being able to correspond at short distances by employing two spherical vessels bearing the letters of the alphabet, each of the letters having suspended from it a magnetized figure attached to a vertical wire.

He likewise alludes to Gellibrand’s discovery, A.D. 1635, of which he was informed by John Greaves, the eminent English mathematician, and he communicates a letter received from the learned French philosopher, le Père Marin Mersenne, containing a distinct account of the same.

His definition of universal magnetism, according to Madame Blavatsky, is very original, for he contradicted Gilbert’s theory that the earth was a great magnet. He asserted that, although every particle of matter and even the intangible “powers” were magnetic, they did not themselves constitute a magnet. There is but one Magnet in the universe, and from it proceeds the magnetization of everything existing. This magnet is, of course, what the Kabalists term the central Spiritual Sun, or God.... He demonstrates the difference between mineral magnetism and zoömagnetism, or animal magnetism, and says that the sun is the most magnetic of all bodies.... It imparts the binding power to all things falling under its direct rays (“Isis Unveiled,” pp. 208–210).

Another Jesuit, Jacobo Grandamico (1588–1672), published in 1645, “Nova demonstratio immobilitatis terræ petita ex virtute magnetica,” wherein he shares fully the views of Niccolas Cabæus, Athanasius Kircher, Vincentus Leotaudus and others of the same Order relative to the earth’s magnetism (Larousse, “Dict.,” Vol. VIII. p. 1445).

REFERENCES.--“Journal des Sçavans” pour 1665 et 1666, pp. 519–525, 571–578; “Nouveau Larousse,” par Claude Augé, Paris, Vol. V. p. 485; “Salmonsen ... konversationsleksikon,” 1900, p. 480; Van Swinden, “Recueil,” 1784, Vol. II. pp. 352, 361, 394, and the different works named in Ronalds’s “Catalogue,” pp. 266–267; ninth ed. “Encycl. Brit.,” Vol. XIV. pp. 93–94.

=A.D. 1644.=--Digby (Sir Kenelme), the very famous Englishman to whom allusion has already been made under the B.C. 600–580 entry, publishes, in Paris, “Two Treatises, in the one of which the Nature of Bodies: in the other, the nature of Man’s Soule is looked into: in Way of Discovery of the Immortality of Reasonable Soules.”[45] In a chapter of this work, entitled “Of the lodestone’s generation and its particular motions,” appears the following interesting reference to Gilbert’s work and reputation: “But to come to experimentall proofes and obseruations vpon the loadstone by which it will appeare that these causes are well esteemed and applyed, we must be beholding to that admirable searcher of the nature of the loadstone, Doctor Gilbert: by means of whom and of Doctor Haruey, our nation may claim euen in this latter age as deserued a crowne for solide Philosophicall learning as for many ages together it hath done formerly for acute and subtile Speculations in Diuinity. But before I fall to particulars, I thinke it worth warning my Reader, how this great man arriued to discouer so much of Magneticall Philosophy; that he, likewise, if he be desirous to search into nature, may, by imitation, advance his thoughts and knowledge that way. In short, then, all the knowledge he gott of this subject was by forming a little loadstone into the shape of the earth. By which meanes he compassed a wonderful designe, which was to make the whole globe of the earth maniable; for he found the properties of the whole earth in that little body; which he therefore called a Terrella, or little earth; and which he could manage and trye experiences vpon att his will. And, in like manner, any man that hath an ayme to aduance much in naturall sciences, must endeauour to draw the matter he inquireth of, into some such modell, or some kinde of manageable methode; which he may turne and winde as he pleaseth. And then lett him be sure, if he hath a competent vnderstanding, that he will not misse of his marke.”

REFERENCES.--“The Private Memoirs of Sir Kenelme Digby, Gentleman of the Bedchamber of King Charles I,” London, 1827; “Dict. of Nat. Biog.,” Vol. XV. pp. 60–66; “New Gen. Biog. Dict.,” London, 1850, Vol. XI. p. 390; “Gen. Biog. Dict.” of Alex. Chalmers, London, 1811, pp. 70–78; “Emerson’s Works,” London, 1873, Vol. II. p. 35; “The Library” for April 1902, has, at pp. 131–132, the arms of the Digbys.

=A.D. 1644.=--Descartes (René), a prominent French philosopher and mathematician, publishes his “Principia Philosophiæ,” divided into four parts; the first giving an exposition of the principles of all human knowledge, the second treating of the principles of natural things, and the third and fourth parts developing his theory of vortices. His main idea was that a rush of subtle matter passes very rapidly through the earth from the equator towards each pole, being opposed by magnetic substances throughout its passage and that the sun is the centre of a vortex of an ethereal fluid, whose whirling motion produces the revolution of planets about the sun, or around the fixed stars. Moreover, as Noad states it, “the vortex moves with the greatest facility in a particular direction, one of its ends being always turned toward the north.”

One of the most prominent fellow-students of Descartes was Marin Mersenne, who joined the religious Order of “Minimes,” and who, after publishing in 1634 and 1639 “Les Mécaniques de Galilée” and “Nouvelles Découvertes de Galilée,” brought out, during the years 1644 and 1647, his well-known “Cogitata physico-mathematica,” which, Montucla says, contains un océan d’observations de toutes espèces ... and embraces a very interesting treatise on navigation besides many letters from leading scientists of that period not elsewhere to be found.

REFERENCES.--“La grande Encyclopédie,” Vol. XXIII. pp. 730–731; Larousse, “Dict.,” Vol. XI. p. 94; “Biographie Générale,” Vol. XXXV. pp. 118–123; “The English Cyclopædia,” Vol. IV. p. 206; Alex. Chalmers, “Gen. Biog. Dict.,” London, 1811, Vol. XXII. pp. 81–83; “Biographie Universelle,” Vol. X. pp. 465–473; Whewell, “Hist. of the Ind. Sc.,” Vol. I. pp. 323, 328, 338, 339, 343, 354, 387, 423, 429, 430; Vol. II. p. 220; likewise pp. 320 and 390 of Vol. I. relative to Le Père Marin Mersenne and pp. 391 and 423 concerning the “Traité de Physique” of James Rohault; Playfair’s Fourth Dissertation in the eighth edition of the “Encycl. Britann.”; “Essai théorique ... des connaissances humaines,” par G. Tiberghien, Bruxelles, 1844, Vol. I. pp. 472–495; Dr. W. Windelband, “History of Philosophy,” New York, 1893, pp. 380–381, 391–396; Dr. F. Ueberweg, “History of Philosophy,” New York, 1885, Vol. II. pp. 41–55; Alfred Weber, “History of Philosophy,” translated by Frank Thilly, New York, 1896, pp. 305–323; Ruard Andala, “Descartes in reality the overturner of Spinosism and the architect of experimental Philosophy”; Erasmus Bartholinus, “De Cometis,” Copenhagen, 1664–1665 (“Biog. Univ.”; Weidler, p. 508) Mahaffy, 1880; Houzeau et Lancaster, “Bibl. Gen.,” Vol. II. for Descartes, p. 119, and for Mersenne, p. 204; “Journal des Savants” for Feb. 1826, p. 103, for Feb. 1827, p. 110, also for Aug.-Oct. 1850, Dec. 1860, Jan.-Feb. 1861, Oct.-Nov. 1869, Feb., April and July 1870, Mar.-April 1880, Aug. 1884, April 1898, Feb. 1899.

=A.D. 1646.=--Browne (Sir Thomas), an eminent English physician and writer, publishes the well-known treatise “Pseudodoxia Epidemica, or Inquiries into Vulgar and Common Errors,” which ran through six editions in twenty-seven years, and upon which his fame is principally established.

With regard to the possibility of such a magnetic telegraph as Strada speaks of he says (Book II. chap. iii.): “The conceit is excellent and, if the effect would follow, somewhat divine; whereby we might communicate like spirits, and confer on earth with Menippus in the moon. And this is pretended from the sympathy of two needles, touched with the same loadstone, and placed in the centre of two abecedary circles or rings, with letters described round about them, one friend keeping one and another keeping the other, and agreeing upon the hour when they will communicate, at what distance of place soever, when one needle shall be removed unto another letter, the other, by wonderful sympathy, will move unto the same.”

As the result of experiment, he found that “though the needles were separated but half a span, when one was moved the other would stand like the pillars of Hercules, and if the earth stand still, have surely no motion at all.... By electrical bodies,” he says, “I understand not such as are metallical, mentioned by Pliny and the ancients; for their electrum was a mixture made of gold, with the addition of a fifth part of silver; a substance now as unknown as true aurichalcum, or Corinthian brass, and set down among things lost by Pancirollus. Nor by electric bodies do I imagine such only as take up shavings, straws and light bodies, amongst which the ancients placed only jet and amber, but such as, conveniently placed unto their objects, attract all bodies palpable whatsoever. I say conveniently placed, that is, in regard of the object, that it be not too ponderous or any way affixed; in regard of the agent, that it be not foul or sullied, but wiped, rubbed and excitated; in regard of both, that they be conveniently distant, and no impediment interposed. I say, all bodies palpable, thereby excluding fire, which indeed it will not attract, nor yet draw through it, for fire consumes its effluxions by which it should attract.”

The different chapters of this second book treat of the loadstone, of bodies magnetical and electrical, of magnetical rocks and attractive mountains, and also make allusion to the cross on the church of St. John in Ariminium, to the reported magnetical suspension of Mahomet’s tomb, etc. etc.

At pp. 64, 81 and 87 of Chap. II he says: “Neither is it onely true, what Gilbertus first observed, that irons refrigerated North and South acquire a directive faculty; but if they be cooled upright and perpendicularly, they will also obtain the same.... Now this kind of practice, Libavius, Gilbertus and lately Swickardus, condemn, as vain and altogether unuseful; because a loadstone in powder hath no attractive power; for, in that form, it omits the polarity and loseth those parts which are the rule of attraction.... Glasse attracts but weakely though cleere, some slick stones and thick glasses attract indifferently; Arsenic not at all; Saltes generally but weakely, as Sal Gemma, Allum and also Talke, nor very discoverably by any frication; but, if gently warmed at the fire and wiped with a dry cloth, they will better develop their Electricities.”

At Chapter XVII of the seventh book of the above-mentioned treatise, Browne makes allusion to “the story of Frier Bacon that made a Brazen Head to speak these words: “Time is....”

REFERENCES.--“Library of Literary Criticism,” Chas. Wells Moulton, Vol. II. p. 339–345; “Fortnightly Review,” for Oct. 1905, pp. 616–626, “Sir Thomas Browne and his Family”; Edmund Gosse, in the “English Men of Letters Series”; Browne’s “Letter” inserted in the “Biographia Britannica,” also his entire works, recognized as an encyclopædia of contemporary knowledge, and which were published in four octavo volumes by Simon Wilkins, F.S.A., London, 1836.

=A.D. 1653.=--In the third edition of “The Jewell House of Arte and Nature,” by Sir Hugh Plat, originally published in 1594, and wrongly attributed in Weston’s “Catalogue” to Gabriel Plattes, is to be found the following allusion to the loadstone: “And though the adamant be the hardest of all stones, yet is it softened with Goa’s blood and there is a special antipathy between that and the loadstone, which is of the colour of rusty iron, and hath an admirable vertue not onely to draw iron to it self, but also to make any iron upon which it is rubbed to draw iron also, it is written notwithstanding that being rubbed with the juyce of Garlick, it loseth that vertue and cannot then draw iron, as likewise if a Diamond be layed close unto it.”

This “special antipathy” of garlick, and of the diamond--whether or not the latter be softened with Goa’s (goat’s) blood--is treated of very fully by many other authors, notably:

Pliny, “Nat. Hist.,” Holland tr. 1601, Chap. IV. p. 610; Plutarch, “Quæstones Platonicæ,” lib. vii. cap. 7; Claudius Ptolemæus, “Opus Quadripartitum,” lib. i. cap. 3; St. Augustine, “De Civitate Dei,” lib. xxi.; Bartholom. de Glanvilla, “Liber de Proprietatibus Rerum,” lib. xvi.; Pietro di Abano, “Conciliator Differentiarum,” 1520, pp. 72–73, or the Venice edition of 1526, cap. 51; Joannes Ruellius, “De Natura Stirpium,” 1536, pp. 125, 530; Ibn Roschd’s “Comment on Aristotle,” 1550, T. IV. p. 143t; Cardinal de Cusa, “Opera,” 1565, p. 175; C. Julius Solinus, “De Memorabilibus,” cap. 64; Walter Charleton, “A Ternary of Paradoxes,” London, 1650, pp. 40–41; Thomas Browne, “Pseudodoxia Epidemica,” 1658, p. 74; G. B. Porta, “Naturall Magick,” 1658, Chap. XLVIII and Chap. LIII--from both of which chapters extracts appear at the A.D. 1558 entry; “Journal des Savants” for January 1894; Chas. de Rémusat, “Hist. de la Philos.,” Paris, 1878, Vol. II. p. 187.

Rohault--at p. 186 of his 1728 “Syst. of Nat. Phil.”--says: “As to what some writers have related, that a loadstone will not attract iron if there be a diamond near and that onions and garlic will make it lose its vertue; these are contradicted by a thousand experiments which I have tried. For I have shown that this stone will attract iron through the very thickest diamonds and through a great many thick skins which an onion is made up of.”

REFERENCES.--“Dict. of Nat. Biography,” Vol. XLV. pp. 407–409, giving many particulars; J. B. J. Delambre, at A.D. 1635. For Gabriel Plattes, see the same “Dict. of Nat. Biography,” Vol. XLV. p. 410.

=A.D. 1657.=--Schott (Gaspar)--P. Gaspar Schott--a German Jesuit who was sent to teach natural philosophy and mathematics at Palermo, Sicily, is the author of several very curious works on physics, of which the most important alone will here be noted.

“Magiæ Universalis Naturæ et Artis,” etc., appeared at Herbipoli in 1657, 1658, 1659. In the first book of the fourth volume (or part) he indicates, according to Kircher, whom he had met while in Rome, the means of conveying one’s thoughts at a distance by the loadstone, and he alludes to the speaking head constructed by Albertus Magnus, while, in the third and fourth books of the same volume, he gives a long treatise on the loadstone as well as an account of numerous experiments made with it.

“De Arte Mechanica,” etc. (“Mechanicæ,” etc.), Herbipoli, 1657–1658, contains, in Part II. class i. p. 314, the first published notice of Von Guericke’s experiments.

“Physica Curiosa sive Mirabilia Naturæ,” etc., Herbipoli, 1662 (which may justly be considered a continuation of the “Magiæ Universalis”), treats in the eleventh book of St. Elmo’s fire, thunder and meteors in general.

“Technica Curiosa sive Mirabilia Naturæ,” etc., Herbipoli, 1664, alludes, in the first two books, to the experiments made by Von Guericke and by Boyle, and gives the contents of eight letters written him by the first named.

“Schola Steganographica,” etc., Norimbergæ, 1665, gives, at pp. 258–264, a description of the dial telegraph of Daniell Schwenter.

“Jocoseriorum Naturæ et Artis,” etc., published about 1666, alludes to the “Thaumaturgus Mathematicus” of Gaspar Ens, published at Cologne, 1651, as well as to the “Deliciæ Physico-Mathematicæ” of Daniell Schwenter and Geo. Philippi Harsdoerffer (Senator of Nuremberg), to “La Récréation Mathématique” of Jean Leurechon, and to the works of Cardan, Mizauld, Aldrovandi and others.

REFERENCES.--“Notice Raisonnée des Ouvrages de Gaspar Schott,” par M. L’Abbé Mxxx de St. Léger de Soissons, Paris, 1785, pp. 6, 31, 32, 37, 44, 70; Muirhead’s translation of Arago’s Eloge de James Watt, London, 1839, p. 51.[46]

=A.D. 1660.=--Guericke (Otto von), a burgomaster of Magdeburg, Prussian Saxony, constructs the first frictional electric machine. It consisted of a globe of sulphur, cast in a glass sphere, and mounted upon a revolving axis, which when rubbed by a cloth pressed against it by the hand, emitted both sound and light. It was Guericke who “heard the first sound and saw the first light in artificially excited electricity.” He proved that light bodies, when attracted by an excited electric, were immediately repelled by the latter and became incapable of a second attraction until touched by some other body; also that light bodies develop electrical excitation when suspended within the sphere of an excited electric.

REFERENCES.--“Experimenta Nova Magdeburgica,” 1672, lib. iv, cap. 15, p. 147, also all relating to the sulphur globe reproduced from the “Experimenta Nova” at end of Figuier’s “Exposition et Histoire,” etc., Vol. IV. Paris, 1857; Moncony, Voyages, 1665; Schott (Gaspar), “Technica Curiosa,” etc., Norimbergæ, 1664; “Abhandlungen zur Geschichte der Mathem.,” Leipzig, 1898, Vol. VIII. pp. 69–112, for the two articles by Ferdinand Rosenberger on the development of the electric machine, etc., from the time of Von Guericke.

=A.D. 1660.=--At the meeting of the English Royal Society, held June 5, 1660, Magnetical Remedies were discoursed of. Sir Gilbert Talbot promised to bring in what he knew of sympatheticall cures, and those who possessed any powder of sympathy were requested to fetch some at the next meeting.

=A.D. 1661.=--Somerset (Edward), second Marquis of Worcester, an English inventor, announces, in his “Century of Inventions” that he has discovered “a method by which at a window as far as the eye can discover black from white, a man may hold discourse with his correspondent, without noise made or notice taken; being, according to occasion given, or means afforded, ex re nata, and no need of provision beforehand: though much better if foreseen, and course taken by mutual consent of parties.” This method, he asserts, he can put into practice “by night as well as by day, though as dark as pitch is black.”

REFERENCES.--Dircks’ “Life of Worcester,” p. 357; “Dictionary of National Biography,” Vol. LIII. pp. 232–237.

=A.D. 1662.=--Rupert (Prince Robert), of Bavaria, son of Frederick V, elector palatine, and one of the founders of the Royal Society of London, is credited with the discovery of the curious glass bubbles called “Rupert’s drops.” These are merely drops of glass thrown, when melted, into water, and thus becoming suddenly consolidated into a shape somewhat resembling the form of a tear. The globular end may be subjected to quite a smart stroke without breaking, but if a particle of the tail is nipped off, the whole flies into fine powder with almost explosive violence.

“Mr. Peter did show us the experiment (which I had heard talked of) of the chymicall glasses, which break all to dust by breaking off a little small end; which is a great mystery to me” (Samuel Pepys, “Diary,” January 13, 1662).

Sir David Brewster discovered that the fracture of these unannealed drops was accompanied by the evolution of electrical light, which appears even when they are broken under water. Mr. Bennet observed that when one of the drops was placed upon a book, the latter was electrified negatively.

REFERENCES.--The articles on “Annealing,” “Optics,” and “Electricity” in the “Encyclopædia Britannica”; also the biography in “Penny Cycl.,” Vol. XX. pp. 226–227; Le Cat, “Memoir,” London, 1749–1750, or Philos. Trans., XLVI. p. 175.

=A.D. 1665.=--Grimaldi (Francesco Maria), Italian philosopher (1618–1663), member of the Order of Jesuits and an associate of the astronomer Giovanni Battista Riccioli (at A.D. 1270) is the author of the important work “Physico mathesis de Lumine ...” which cites the discovery of magnetism produced by the perpendicular holding of an iron bar.

REFERENCES.--Phil. Trans. for 1665; “Engl. Cycl.,” article “Biography,” Vol. CXI. p. 207; Larousse, “Dict.,” Vol. VIII, p. 1531. And, for Riccioli’s works, see Houzeau et Lancaster, “Bibliog. Gén.,” Vol. III. p. 238; “Journ. des Sçavans” pour 1665 et 1666, pp. 642–647.

=A.D. 1665.=--Glanvill (Joseph), an eminent English divine and philosopher, Chaplain to King Charles II and F.R.S., sometimes called “Sadducismus Triumphatus Glanvill,” endorses in his “Scepsis Scientifica” (“the vanity of dogmatizing recast”)--published originally in 1661--the views advanced previously by the Jesuit Leurechon, and, after discussing the objections of Sir Thomas Browne, expresses the belief that “to confer at the distance of the Indies by sympathetic conveyances may be as usual to future times as to us in literary correspondence.”

A writer in the “Bath Chronicle” reproduced a long extract from Glanvill’s work, the concluding sentence of which, he says, seems to have anticipated the electric telegraph. It is as follows: “But yet to advance another instance. That men should confer at very distant removes by an extemporary intercourse is a reputed impossibility; but yet there are some hints in natural operations that give us probability that ’tis feasible, and may be compassed without unwarrantable assistance from demoniack correspondence. That a couple of needles equally touched by the same magnet, being set in two dials exactly proportioned to each other, and circumscribed by the letters of the alphabet, may effect this ‘magnale’ (i. e. important result) hath considerable authorities to avouch it.

“The manner of it is thus represented: Let the friends that would communicate take each a dial, and, having appointed a time for their sympathetic conference, let one move his impregnate needle to any letter in the alphabet, and its affected fellow will precisely respect the same. So that, would I know what my friend would acquaint me with, ’tis but observing the letters that are pointed at by my needle, and in their order transcribing them from their sympathized index, as its motion directs; and I may be assured that my friend described the same with his, and that the words on my paper are of his inditing. Now, though there will be some ill-contrivance in a circumstance of this invention, in that the thus impregnate needles will not move to, but avert from each other (as ingenious Dr. Browne hath observed), yet this cannot prejudice the main design of this way of secret conveyance; since it is but reading counter to the magnetic informer, and noting the letter which is most distant in the Abecederian circle from that which the needle turns to, and the case is not altered.

“Now, though this desirable effect may possibly not yet answer the expectations of inquisitive experiment, yet ’tis no despicable item, that by some other such way of magnetick efficiency it may hereafter with success be attempted, when magical history shall be enlarged by riper inspections; and ’tis not unlikely but that present discoveries might be improved to the performance.”

Glanvill is also the author of “Philosophical Considerations Touching Witches and Witchcraft,” 1666, and of “The Sadducismus Triumphatus,” 1681.

REFERENCES.--“Dict. of Nat. Biog.,” 1908, Vol. VII. pp. 1287–8; Larousse, “Dict.,” Vol. VIII. pp. 1294–1295; “Nature,” Vol. XVI. p. 269; “Histoire de la Philosophie,” par Charles de Rémusat, Paris, 1878, Vol. II. chap. xi. pp. 184–201; “The General Biog. Dict.,” Alex. Chalmers, London, 1811, Vol. XVI. pp. 12–17; “Joseph Glanvill,” by Ferris Greenslet, New York, 1905; “Imperial Dict. of Universal Biography,” Vol. II. p. 642.

=A.D. 1666.=--Denys (William), hydrographer, of Dieppe, observes that the compasses placed in different parts of a vessel give different indications (Becquerel, “Magnétisme,” p. 119; “Journal des Sçavans” pour 1665 et 1666, p. 538).

=A.D. 1671.=--Richer (T.), French philosopher, who was sent by the Paris Academy of Sciences to the island of Cayenne for the purpose of determining the amount of terrestrial refraction and for other astronomical objects, is the first to make known the electrical powers of the gymnotus electricus.

REFERENCES.--Leithead, “Electricity,” Chap. XII; Fahie, “El. Tel.,” p. 171; Bertholon, “Elec. du Corps Humain,” 1786, Vol. I. p. 171; Mém. de l’Acad. des Sciences, 1677, Art. VI; Richer, “Observations,” etc., Paris, 1679; Bancroft, at A.D. 1769; “Cosmos,” 1859, Vol. V. pp. 23–24.

=A.D. 1671.=--Rohault (Jacques), a French philosophical writer, and one of the earliest, ablest and most active propagators of the Cartesian philosophy in France, publishes at Paris the first edition of his “Traité de Physique,” at Part III. chap. viii. pp. 198–236 of which he treats especially of amber and of the loadstone. The same passages can be seen at Vol. II. part iii. chap. viii. pp. 163, etc., of Rohault’s “System of Natural Philosophy,” published in London during the year 1723, and at the same chapter, pp. 388, etc., of “Jacobi Rohaulti Physica,” Londini, 1718.

The latter is the last and best edition of the well-known classical translation, originally made in 1697, by Dr. Samuel Clarke, who was the friend of Sir Isaac Newton and chaplain to Bishop Moore, of Norwich. Through this work Clarke introduced very many critical notes exposing the fallacies of the Cartesian system. The “Physica” passed through four editions as the Cambridge University textbook before it was made to give way to the treatises of Newton.

=A.D. 1672.=--Sturm (John Christopher), a very able German mathematician, who was for thirty-four years professor of natural philosophy at the University of Altdorf (Franconia), and who, after vainly attempting to satisfactorily unite the Aristotelian and Cartesian doctrines finally adopted the Baconian philosophy, establishes the “Collegium Curiosum” on the plan of the celebrated Italian “Accademia del Cimento,” alluded to under the A.D. 1609 date.

The society was founded for the purpose of studying, repeating and even modifying the most notable philosophical experiments of the day, such as those made by Von Guericke, Boyle, Hooke and others, and its proceedings were published in 1676 and 1685 under the title of “Collegium Experimental sive Curiosum, etc.”

=A.D. 1673.=--Hevelius--Hevel--Hovel--Hövelke (Joannes), an eminent Polish astronomer, member of the English Royal Society, and a great friend more particularly of le Père M. Mersenne, of Gassendi and of Kircher, publishes during 1673 the first part of his great work “Machina Cœlestis”--dedicated to Louis XIV--the entire second part of which, issued in 1679, was destroyed by fire with the exception of seven copies. This explains its extreme scarcity. It was this work which led to the public controversy between Hevelius and Dr. Hooke who published, in London, during 1674 his “Animad. in Mach. Celest. Hevelii.”

It is said that, next to John Flamsteed, Hevelius was the most accurate observer of the heavens in his day (“The Reliquary,” London, Vol. XIV. pp. 149–159 and Vol. XV. pp. 34–38; “Journal des Savants” for March, June and November 1836). He had already published “De Variatione acus magneticæ” (Opusc. Act. Erudit. Lips., Vol. I. p. 103), also a report of the variations of the magnetical needle during 1670, which can be found in the Phil. Trans., Vol. V. for 1670, p. 2059, or in Hutton’s abridgments, London, 1809, Vol. I. p. 514.

REFERENCES.--Larousse, “Dict.,” Vol. IX. pp. 266–267; “Biog. Gén.,” Vol. XXV. pp. 285–294; Delambre, “Hist. de l’Astron. Mod.,” Vol. II. pp. 434–484; Weidler, “Hist. Astron.,” p. 485; “Mem. Roy. Soc.,” 1739, Vol. I. p. 274.

=A.D. 1675.=--Boyle (Robert), Irish natural philosopher and chemist, seventh son of Richard Boyle, Earl of Cork, and one of the first members of what he calls the “Invisible” or “Philosophical” College, which has since become the Royal Society,[47] gives, in his “Philosophical Works,” the result of his many experiments upon magnetism and electricity.

John Evelyn in his letter to Mr. Wotton, March 30, 1695 (“Memoirs, Diary and Correspondence,” by Wm. Bray, London, p. 716), says of Boyle: “It must be confess’d that he had a marvailous sagacity in finding out many usefull and noble experiments. Never did stubborn matter come under his inquisition but he extorted a confession of all that lay in her most intimate recesses; and what he discover’d he as faithfully register’d, and frankly communicated....”

Prof. Tyndall remarks (“Lecture,” February 4, 1875): “The tendency to physical theory showed itself in Boyle. He imagined that the electrified body threw out a glutinous or unctuous effluvium, which laid hold of small bodies, and, in its return to the source from which it emanated, carried them along with it.”

A few of his many characteristic remarks and observations are, however, best given in his own words, as extracted from the “Philosophical Works” above alluded to:

“The invention of the mariner’s needle, which giveth the direction, is no less benefit for navigation than the invention of the sails, which give the motion” (London, 1738, Vol. I. p. 62).

“I, with a certain body (rough diamond), not bigger than a pea, but very vigorously attractive, moved a steel needle, freely poised, about three minutes after I had left off rubbing it” (Vol. I. p. 508). Speaking elsewhere of his experiments with diamonds, he says: “But when I came to apply it (the loadstone) to one more, which look’d somewhat duller than almost any of the rest, I found that it had in it particles enough of an iron nature to make it a magnetical body and observed without surprise that not only it would suffer itself to be taken up by the strongest pole of the loadstone, but when the pole was offer’d within a convenient distance it would readily leap through the air to fasten itself to it.”

“I removed a piece of amber in the sunbeams till they had made it moderately hot and then found it would attract those light bodies it would not stir before” (Vol. I. p. 400, and Vol. III. p. 52).

“Whether from such experiments one may argue that it is but, as it were, by accident that amber attracts another body, and not this the amber; and whether these ought to make us question, if electrics may, with so much propriety, as has been generally supposed, be said to attract, are doubts, that my design does not oblige me to examine” (Vol. IV. p. 350).

REFERENCES.--John Evelyn’s “Diary,” Letter to Mr. Wotton, March 30, 1696; Libes’ “Histoire Phil. du Progrès de la Physique,” Paris, 1810; Boyle’s “Mechanical Origine or Production of Electricity,” 1675; Birch, “Life of Hon. R. Boyle,” 1743–1744; Secondat’s “Histoire d’Electricité” (Observations physiques), 1750, p. 141; Whewell, “Hist. of Ind. Sciences,” 1859, Vol. I. pp. 395, 396. Priestley’s “History of Electricity,” 1775, pp. 5–8; M. Reael, “Observ. a. d. Magnectsteen,” 1651, alluded to at note, p. 486, Vol. I. of Van Swinden’s 1784 “Recueil,” etc.; Van Swinden, Vol. II. pp. 353, 359–361; “Biblioth. Britan.” (Authors), Robt. Watt, Edinburgh, 1824, Vol. I. pp. 142–3; Aikin’s “G. Biography,” and Martin’s “Biog. Philosophica,” in “General Biog. Dict.,” by John Gorton, London, 1833, Vol. I; Phil. Trans., Vol. VIII for 1673, p. 6101 and Hutton’s abridg., Vol. II. p. 90; Boyle, London, 1673, “Essays of the ... Effluviums” (Subtility), pp. 38–42, 52–53; (Efficacy) pp. 18, 19, 32, 33; (Determinate Nature) pp. 21, 57; “An Essay ... of Gems,” London, 1672, pp. 108–129; Ch. W. Moulton, “Library of Literary Criticism,” Vol. II. pp. 416–420; “Critical Dict. of Engl. Lit.,” S. Austin Allibone, Philad., 1888, Vol. I. pp. 232–233; “Essays in Historical Chemistry,” T. E. Thorpe, London, 1894, pp. 1–27; Eighth “Britannica,” V. p. 259 for notes of Boerhaave, also the “Britannica” 1st Dissertation, p. 47, and 4th Dissertation p. 597; “History and Heroes of the Art of Medicine,” J. Rutherfurd Russell, London, 1861, pp. 233–246.

Consult also Boyle’s “New Exper. Physico-Mechanical,” etc., in which the 16th Exp. is “concerning the operation of the loadstone”; Boyle’s “A Continuation of New Exp.,” etc., in which the 31st Exp. is “about the attractive virtue of the loadstone in an exhausted receiver,” and in which are “Notes, etc., about the atmospheres of consistent bodies,” etc., as well as “Observations about the exciting of the electricity of bodies,” and concerning the electrical emanations and effluviums. Boyle’s “Tracts Containing Some Suspicions Concerning some Occult Qualities of the Air; with an Appendix Touching Celestial Magnets,” etc. His “Phil. Works,” London, 1744, Vol. III. pp. 65, 67 and 70, 647, etc., give “Experiments and Notes about the Mechanical Origin or Production of Electricity.”

For full accounts of the Royal Society, alluded to above, see the histories written by Thomas Sprat (1667), by Thomas Birch (1756), by Thomas Thomson (1812), and by Chas. Richard Weld (1847–1848).

=A.D. 1675.=--Picard (Jean), eminent astronomer, who succeeded Gassendi (A.D. 1632) as professor of astronomy at the Collège de France, is the first to observe electric light in vacuo. According to Tyndall (“Lessons in Electricity,” p. 88) it was while carrying a barometer from the Observatory to the Porte Saint-Michel in Paris that he noticed light in the vacuous portion. Sebastien and Cassini observed it afterwards in other barometers (see Tyndall’s “Lecture V.” p. 91, for Priestley’s description of the electric light in vacuo).

It was this same scientist who had already given, in his “Mesure de la Terre,” 1671, Article IV, the description of the measurement of a degree of latitude made with instruments of his own manufacture.

REFERENCES.--Humboldt, “Cosmos,” 1859, Vol. V. pp. 23, 24; Larousse, “Dict.,” Vol. XII. p. 937; “Phil. Hist. and Mem. of the Roy. Acad. at Paris,” London, 1742, Vol. I. pp. 208–221.

=A.D. 1675.=--Newton (Sir Isaac), prominent English mathematician and natural philosopher, of whom Macaulay says that “in no other mind have the demonstrative faculty and the inductive faculty coexisted in such supreme excellence and perfect harmony,” communicates to the Royal Society his discovery that excited glass will attract any light bodies even to the surface opposite to that upon which it has been rubbed. This was successfully demonstrated by the Society, January 31, 1676.

He improved the electric machine by substituting a glass globe for the globe of sulphur made use of by both Von Guericke and Boyle, the rubbers in every case being the hands of the operator.

He appears to have somewhat anticipated Franklin’s great discovery, judging by the following letter he addressed, December 15, 1716, to the Rev. Dr. Law, in Suffolk:

“Dear Doctor,” it begins, “He that in ye mine of knowledge deepest diggeth, hath, like every other miner ye least breathing time, and must sometimes at least come to terr; alt (terra alta) for air. In one of these respiratory intervals I now sit doune to write to you, my friend. You ask me how, with so much study, I manage to retene my health. Ah, my dear doctor, you have a better opinion of your lazy friend than he hath himself. Morpheus is my best companion; without eight or nine hours of him ye correspondent is not worth one Scavenger’s peruke. My practizes did at ye first hurt my stomach, but now I eat heartily enow, as y’ will see when I come down beside you. I have been much amused by ye singular φενομενα resulting from bringing a needle into contact with a piece of amber or resin fricated on silke clothe. Ye flame putteth me in mind of sheet lightning on a small--how very small--scale. But I shall in my epistles abjure philosophy, whereof when I come down to Sakly I’ll give you enow. I begin to scrawl at five mins. from nine of ye clk, and have in writing consumed ten mins. My Lord Somerset is announced.”

Æther, according to Sir Isaac Newton, is a thin subtile matter much finer and rarer than air. Sometimes, it is termed by him, a subtil spirit, as in the latter part of his “Principia,” and sometimes a subtil ætherial medium, as in his “Optics.” By many it is supposed to pervade all space, also the interior of solid bodies, and to be the medium of the transmission of light and heat. The æther of Descartes was his materia subtilis or his First Element: by which he understood a “most subtil matter very swiftly agitated, fluid, and keeps to no certain figure, but which suits itself to the figure of those bodies that are about it. His Second Element consists of small Globules; that is, bodies exactly round and very solid, which do not only, like the First Element, fill up the pores of bodies but also constitute the purest substance of the Æther and Heaven” (Blome’s translation of Descartes’ “Philosophy,” p. 101; R. Lovett, “The Subtil Medium Prov’d”; Phil. Mag., Vol. XVIII. p. 155).

During the years 1686 and 1687 Newton composed his “Principia,” a work which Lagrange pronounced “la plus haute production de l’esprit humain”: “the greatest work on science ever produced” (Sir Robt. Ball), and “which will be memorable not only in the annals of one science or of one country, but which will form an epoch in the history of the world.” This was published at Halley’s expense. As Brewster says (1686, Chap. XII): “It is to Halley alone that science owes this debt of gratitude. It was he who tracked Newton to his college, who drew from him his great discoveries, and who generously gave them to the world.”

In the twenty-third proposition of the second book, fifth section, Newton says: “The virtue of the magnet is contracted by the interposition of an iron plate and is almost terminated at it, for bodies further off are not so much attracted by the magnet as by the iron plate.” And in Book III. prop. vi. he thus expresses himself: “The magnetic attraction is not as the matter attracted; some bodies are attracted more by the magnet, others less; most bodies not at all. The power of magnetism in one and the same body may be increased and diminished, and is sometimes far stronger for the quantity of matter than the power of gravity; and in receding from the magnet decreases, not in the duplicate, but almost in the triplicate proportion of the distance, as nearly as I could judge from some rude observations.”

Newton is said to have carried in his ring a magnet weighing but three grains, which could raise 746 grains, or nearly 250 times its own weight. This magnet naturally excited much admiration, but is greatly surpassed in power by that formerly belonging to Sir John Leslie, and now in the Physical Collection at Edinburgh, weighing three and one-half grains, and having a carrying power of 1560 grains.

REFERENCES.--Brewster’s “Life of Sir I. Newton,” pp. 307, 308; “Dict. of Nat. Biog.,” Vol. XL. pp. 370–393; Ch. W. Moulton, “Library of Literary Criticism,” Vol. II. pp. 710–726; “Bibl. Britan.” (Authors), Robt. Watt, Edinburgh, 1824, Vol. II., p. 701; Harris, “Magnetism,” Vol. III. p. 11; Ninth “Britannica,” Vol. XV. p. 274; Whewell, “Hist. of the Ind. Sciences,” 1858, Vol. I. pp. 385–488; the interesting note at foot of p. 683 of the Fourth Dissertation in the “Encyclopædia Britannica”; “Muspratt’s Chemistry,” Vol. II. p. 255; the English “Chemical News” for November 1867, and January 1868, reproducing Sir David Brewster’s letters to the London “Athenæum” and London “Times,” likewise Dr. Crompton’s paper read before the Manchester Literary and Philosophical Society in October 1866; _Phil. Trans._, Vol. LXIV. Part I for 1774, p. 153: “Remarks of John Winthrop upon ... Castillione’s Life of Sir Isaac Newton”; Dr. Geo. Miller, “Hist. Phil. Ill.,” London, 1849, Vol. III. pp. 414–415; “Newton, sa vie et ses œuvres” in “Cosmos,” September 27, 1890 to December 13, 1890; “Journal des Savants” for April, May and June 1832; for April 1846, March, April, May, June, July and August 1852, October, November 1855; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II, 1882, pp. 213–214, 1586; “Hist. de la Philosophie,” par Chas. de Rémusat, Paris, 1878, Vol. II. chap. xii. pp. 202–222.

=A.D. 1676.=--Haward, master of several sailing vessels, and a man of good credit (Phil. Trans., Vol. XI. No. 127, p. 647, of July 18, 1676), states that “being on board of the ship Albemarle, July 24, 1641 ... in latitude of Bermuda ... after a terrible clap of thunder ... it was found that the compass card was turned around, the N. and S. points having changed positions and, though Mr. Grofton brought with his finger the flower-de-lys to point directly N., it would immediately, as soon as at liberty, return to this new unusual posture, and upon examination he found every compass (three) in the ship of the same humour; which ... he could impute to nothing else but the operation of the lightning or thunder mentioned.” The above is also alluded to at p. 33 of Vol. III. of Boyle’s “Phil. Works,” London, 1738, with this addition: “One of the compasses, pointing West, was brought to New England, where, the glass being broke and the air gaining entrance, it lost its virtue. But one of the others is in that country possess’d by Mr. Encrease Mather, the North point of the needle remaining South to this day.”

=A.D. 1677.=--At p. 14 of an exceedingly curious publication entitled “A Rich Cabinet with a Variety of Inventions,” etc., written by J. W. (i. e. John White, of London), who calls himself “a lover of artificial conclusions,” will be found an article on “Divers rare, conceited motions performed by a magnet or loadstone.”

=A.D. 1678.=--Redi (Francesco), well-known Italian scientist, physician to the Grand Duke Ferdinand II, publishes his “Experimenta circa res diversas Naturales,” wherein he is first to communicate the fact that the shock of the raia torpedo can be transmitted to the fisherman through the line and rod connecting him with the fish.

REFERENCES.--Leithead, “Electricity,” Chap. XII; the Firenze, 1671 ed. of Redi’s “Esperienze,” etc., pp. 47–54; Phil. Trans. for 1673, Vol. VIII. p. 6003; Sci. Am. Supp., No. 457, pp. 7300–7302; Matteucci, “Recherches,” 1837 and 1867; Eschinardi (F. della Compagnia di Gesü), “Lettera al S. Francesco Redi,” Roma, 1681, wherein are detailed many curious experiments, including some treating of the magnetic needle by which agency are foretold sudden attacks of earthquakes, etc. etc.

=A.D. 1679.=--Maxwell (William)--Guillelmo Maxvello--native of Scotland, author of “Medicina Magnetica,” offers to prove to various medical faculties that, with certain magnetic means at his disposal, he could cure any of the diseases abandoned by them as incurable (Blavatsky, “Isis,” Vol. I. p. 215).

REFERENCE.--J. H. Van Swinden, “Recueil de Mémoires,” etc., La Haye, 1784, Vol. II. p. 367.

=A.D. 1683.=--Arrais (Edoardo Madeira), who had been physician to--João--John IV, the first Portuguese king of the house of Braganza, is the author of this much-delayed edition of a book entitled “Arbor Vitæ, or a physical account of the Tree of Life in the Garden of Eden.” It treats of occult qualities under the headings of “Doubts,” of which latter there are eight separate ones which constitute as many different chapters, from which the following extracts will prove interesting:

“Doubt” 5, p. 45. “Doth not the fish called Torpedo render the fishes that swim over it immovable, and stupefy the fisher’s arm with its virtue diffused along his spear?”

“Doubt” 5, p. 46. “... as also there are divers sorts of fishes that bring numness, as our Torpedo doth.”

“Doubt” 5, p. 49. “And those that travail the coasts of Brasile make mention of another fish, which causeth numness as our Torpedo doth: whence it becomes sufficiently manifest that there are many kinds of Torpedoes to be found. But this kind lives especially in the river Itapecuro, in the country of the Maragnani, and it is called Perache, or, as Gaspar Barlæus observed, Puraquam, among those Barbarians. In shape and greatness it resembles a kind of lamprey (or Muræna); they use to kill it by striking it with staves; but the arm of him that strikes and then his whole body is stupefied, and shakes presently. Of which thing, Frier Christopher Severineus, Bishop elect of Angola is my ocular witness....”

“Doubt” 7, p. 93. “For it is evident from experience that iron is so indisposed by some qualities that it cannot be moved by the magnet. That fishes swimming over the Torpedo, enclosed in the mud or sand for the purpose, when they come to the places whereto the virtue of the Torpedo is extended can stir no further; by which art she catches and eats them, as Aristotle relates (6 ‘de Hist. Animal.,’ cap. 10; and 9 ‘de Hist.,’ cap. 37).”

“Doubt” 7, p. 94. “For if amber be dulled by moisture, its virtue cannot produce motion in straws. If the virtue of the Torpedo reach the fishes swimming over her, or the fisher’s arm their motive power cannot produce motion.”

“Doubt” 7, p. 96. “And for this cause, the virtue of the magnet can produce motion in iron, not in other bodies, because it finds in it Dispositions necessary on the part of the agent which, being present, it can operate; not in other things. And, for the same reason, amber moves straws, not iron nor stones.”

The preface to the “Arbor Vitæ ...” is written by Richard Browner M.L. Coll. Med., London, who translated out of Latin “The Cure of Old Age,” by Roger Bacon, wherein he gives quite a good account of the latter’s life and writings, and from which we extract but one passage likely here to be of some little interest, viz. at p. 155, regarding the component parts of a medicine: “By Amber here our author intends Amber Gryse (a bituminous body found floating on the sea): For he calls it Ambra and not Succinum (which is solid Amber). Besides, Succinum was never reckoned a spice as Amber is here. And though both Ambra and Succinum be great restorers of the animal spirits, yet the former is more efficacious.”

The “Biographie Générale,” Vol. III. p. 348, says that Duarte Madeyra Arraess, who died at Lisbon in 1652, was the author also of “Apologia,” 1638, of “Methodo,” 1642, and of “Novæ Philosophiæ,” 1650.

=A.D. 1683.=--Halley (Edmund), LL.D., who became English astronomer royal, makes known his theory of four magnetic poles and of the periodical movement of the magnetic line without declination. He states that the earth’s magnetism is caused by four poles of attraction, two of them being in each hemisphere near each pole of the earth. By the word pole he means a point where the total magnetic force is a maximum, or, as he himself styles it, “a point of greatest attraction” (Walker, “Magnetism,” p. 317, etc.).

One of the magnetic poles he places near the meridian of Land’s End, not above 7 degrees from the North Pole, the other being about 15 degrees from the North Pole in the meridian of California, while the two south magnetic poles are placed respectively about 16 and about 20 degrees from the South Pole of the earth, and 95 degrees west, 120 degrees east of London.

In order to test Halley’s theory, the English Government permitted him to make three voyages in the Atlantic Ocean (1698, 1699, 1702), in vessels of which he had the command as post-captain. Humboldt states that these were the first expeditions equipped by any government for the establishment of a great scientific object--that of observing one of the elements of terrestrial force on which the safety of navigators is especially dependent.

The result of these voyages was the construction of the first accurate Magnetic Chart, whereon the points at which navigators have found an equal amount of variation were connected together by curved lines. This was the model of all charts of a similar nature since constructed. Halley remarked upon its completion: “The nice determination of the variation, and several other particulars in the magnetic system, is reserved for a remote posterity. All that we can hope to do is to leave behind us observations that may be confided in, and to propose hypotheses which after-ages may examine, amend or refute.”

See copy of his chart in Vol. I. No. I of “Terrestrial Magnetism,” also in Musschenbroek’s “Essais de Physique,” or, preferably, in Bouguer’s “Traité de Navigation,” where the lines for 1700 are in red ink, while those for 1744 are traced in black, thus readily indicating the changes in the declination.

REFERENCES.--Cavallo, “Magnetism,” and “Nat. or Exp. Phil.,” Vol. II. p. 273; Lloyd, “Treatise on Magnetism,” 1874, p. 102; Sci. Am. Suppl., No. 224, pp. 3570, 3571; Whewell, “Hist. of the Inductive Sciences,” 1859, Vol. I. pp. 396–8, 435–7, 450, 451, 480, 481, and Vol. II. p. 225; Giambattista Scarella, “De Magnete,” 1759, Vol. II; also G. Casali, “Sopra la Grandine,” etc., 1767; “The Phil. Hist. and Mem. of the Roy. Ac. of Sciences at Paris,” London, 1742, Vol. I. p. 245; Vol. II. pp. 240–244, 270, 349; “Magnetic Results of Halley’s Expedition (1698–1700)” in “Terrestrial Magnetism,” September 1913, pp. 113–132; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. pp. 156–7; Dr. G. Hellmann “Neudrucke von schriften,” Nos. 4 and 8; Humboldt, “Cosmos,” 1859, Vol. V. pp. 59–60; John Wallis’s letters to Halley, London (Phil. Trans. for 1702–1703), p. 106; Phil. Trans. for 1667, 1683, 1692; “Memoirs of the Roy. Soc.,” 1739, Vol. II. p. 195; “A Bibliography of Dr. Edmund Halley,” by Alex. J. Rudolph, in the “Bulletin of Bibliography” for July 1905; “Old and New Astronomy,” by Richard A. Proctor, 1892, pp. 37–38; Phil. Trans. Vol. XIII for 1683, No. 148, p. 208; Vol. XVII. p. 563; Vol. XXIII. p. 1106; Vol. XXIX. p. 165; Vol. XLII. p. 155; Vol. XLVIII. p. 239, also the following abridgments: Hutton, Vol. II. p. 624; Vol. VI, pp. 99, 112; J. Lowthorp, Vol. II. p. 285; Reid and Gray, Vol. VI. p. 177; Eames and Martyn, Vol. VI. pp. 28, 286; Baddam, 1745, Vol. II. pp. 195–202; Vol. III. pp. 25–32.

AURORA BOREALIS, OR NORTHERN POLAR LIGHT

Dr. Halley was the first to give (Phil. Trans., No. 347) a distinct history of this phenomenon, which has certainly an electric as well as magnetic origin, and to which Gassendi originally gave the name it now bears, as has been stated at A.D. 1632.

According to Dr. Lardner (“Lectures,” Vol. I. p. 137), Prof. Eberhart, of Halle, and Paul Frisi, of Pisa, first proposed an explanation of the aurora founded upon the following: 1. Electricity transmitted through rarefied air exhibits a luminous appearance, precisely similar to that of the aurora borealis. 2. The strata of atmospheric air become rarefied as their altitude above the surface of the earth is increased, a theory which has since been countenanced by many scientists. It has been observed, notably by Dalton, of Manchester, that the primitive beams of the aurora are constantly in a direction parallel to that of the dipping needle, and that the latter appears most affected when the aurora is the brightest. Arago noticed that the changes of inclination amounted, upon one occasion to 7’ or 8’. The discovery that the magnetic needle was agitated during the presence of an aurora has been ascribed to Wargentin (Am. Journal Sc., Vol. XXX. p. 227), though it is claimed by the friends of Olav Hiörter (see A.D. 1740), that it was independently ascertained by the latter during the year 1741.

The well-known Swiss chemist Auguste Arthur De la Rive has made many important observations upon the electric character of the aurora, the experiments carried on by him in the mountains of Finland being thus described: “We surrounded the peak of a mountain with copper wire, pointed at intervals with tin nibs. We next charged the wire with electricity, and nearly every night during our stay produced a yellowish white light on the tin points, in which the spectroscope analysis revealed the greenish yellow rays so characteristic of the aurora borealis. On the peak of Pietarintumturi we were especially successful, an auroral ray making its appearance directly over and about 150 yards above the copper coil.”

A complete list of all auroras appearing prior to 1754 is to be found in Jean Jacques d’Ortons de Mairan’s, Paris, 1731, “Traité Physique de l’Aurore Boréale,” and a catalogue of auroræ observed, 1800–1877, has been made up by M. Zenger (Sci. Am. Supp., p. 10915). One of the most interesting displays is known as the purple aurora, alluded to in the Annals of Clan-mac-noise as having appeared A.D. 688 (Biot “Note sur la direction,” etc., Comptes Rendus, Tome XIX for 1844, p. 822). Between September 19, 1838, and April 8, 1839, Lottin, Bravais, Lilliehöök and Siljeström observed 160 auroras at Bossekop (69° 58’ N. lat.) in Finmark and at Jupvig (70° 6’ N. lat.); they were most frequent during the period the sun remained below the horizon, that is, from November 17 to January 25. During this night of 70 times 24 hours there were 64 auroras visible (Comptes Rendus, Tome X. p. 289; Martin, “Météorologie,” 1843, p. 453; Argelander, in the “Vorträgen geh. in der Königsberg Gesellschaft,” Bd. I. s. 259).

A Finnish physicist, named S. Lenström, who had been attached to the Nordenskjold Polar Expedition of 1868, visited Lapland in 1871, and, after a series of important observations, constructed an apparatus that permitted him to “artificially reproduce the light of the aurora.” The intensity of this light is so great at times that Lowenörn perceived the coruscations in bright sunshine on the 29th of January, 1786, and Parry saw the aurora throughout the day during the voyage of 1821–1823.

The height of the aurora has been variously estimated, but it is seldom found to be less than forty-five miles above the surface of the earth. Father Boscovich estimated at 825 miles the height of the one observed by the Marquis of Poleni on the 16th of December, 1737. The extent of the aurora, according to Dalton, has been known to cover an area of 7000 or 8000 square miles.

REFERENCES.--“Mem. de Turin,” An. 1784–5, Vol. I. part ii. pp. 328, 338; Young, “Lectures,” Vol. I. pp. 687, 716; Herschel, “Prelim. Discourse,” pp. 93, 329, 330; Phil. Trans., 1753, p. 350; Müller’s “Kosmischen Physik”; Noad, “Manual,” pp. 225–237; also all the references at pp. 187–196, Vol. I of Humboldt’s “Cosmos,” Bohn, London, 1849, as well as in Ronalds’ “Catalogue,” pp. 23–24; Mairan, at Vol. X. p. 961, “Dict. Univ.,” and Vol. XXVI. p. 161, of the “Biog. Universelle”; Trans. Cambridge Phil. Soc., Vol. I; “Isis Unveiled,” Vol. I. pp. 417, 418.

See likewise the “Pharsalia” of Marcus Annæus Lucanus, translated by J. Krais, I. pp. 518–527; Plutarchus, “De facie in orbe lunæ,” cap. 26; the “Annals” of Caius Cornelius Tacitus, Germania, XLV. 1st ed., Venice, 1470; “Das Polarlicht,” H. Fritz, Leipzig, 1881, pp. 4–6, 332; Mairan’s “Traité Physique,” etc., 1731, pp. 179–181; Grégoire du Tour, Lumière Electrique, 1882, Vol. VII. p. 389; Elias Loomis, “The Aurora Borealis,” etc., p. 220 of the Reports of Smiths. Inst., 1865; A. M. Mayer, “Observations,” etc., Amer. Jour. of Sc., February 1871; “A copy of the Catalogue of Aurorae Boreales observed in Norway from the earliest times to June 1878” (“Nature,” December 4, 1902, p. 112); “La cause de l’aurore boréale,” Claudius Arrhenius, in the Revue Générale des Sciences for January 30, 1902, pp. 65–76; “Les Années Météores,” in “Le Cosmos,” Paris, May 25, 1889, etc.; “Terrestrial Magnetism,” March 1898, p. 7 for Chronological Summary of Authors re Aurora; Rev. Jas. Farquharson in “Abstracts of Sc. Papers Roy. Soc.,” Vol. II. p. 391; Wm. Dobbie, Phil. Mag., Vol. LXI for 1823, p. 252; W. Derham, for description of Auroras (in Phil. Trans. for 1728, p. 453); see, for Boscovitch, “Journal des Savants,” February 1864; “Journal des Savants,” for August 1820; C. H. Wilkinson, “Elements,” 1804; Vol. II. p. 279 and note; Calogera’s “Raccolta,” XVII. 47, Proc. of the Royal Soc. of Edinburgh for the observations of J. A. Brown and others on the aurora; F. C. Meyer, De luce boreali, 1726; Poggendorff, I. 135; Sturgeon, “Sc. Res.” 4th Sec. p. 489; Phil. Trans., Vol. XXXVIII. p. 243; Vol. XLVI. p. 499; F. Zöllner’s paper in “L. E. and D. Philos. Mag.,” for May and July, 1872; C. A. Young, Amer. Jour. of Sc., Vol. III., 3rd s., p. 69; Baron Karl Von Reichenbach’s “Physico-Physiological Researches,” trans. of Dr. John Ashburner, London, 1851, pp. 5–36, also pp. 445, etc., of the translation of Dr. W. Gregory, London, 1850; J. H. Van Swinden, “Recueil de Mémoires,” etc., La Haye, 1784, Vol. III. p. 187, etc.; J. E. B. Wiedeburg, “Beobachtungen und Muth.,” etc., 1771; G. W. Krafft, “Observ. Meteor,” etc., in Novi Com. Acad. Petrop., Vol. V. p. 400; Giuseppe Toaldo, “Descrizione,” etc., in Saggi ... Accad. di Padova, Vol. I. p. 178; Louis Cotte, “Table of Auroræ, Observed ... 1768–1779,” Paris, 1783; Journal de Physique for 1775; Recueil de Mem. de l’Acad. des Sciences for 1769; A. S. Conti, “Rifflessioni sull’ Aurora Boreale.”[48]

For Auguste Arthur De la Rive, consult “Bibl. Britan.,” Vol. XVI, N.S., 1821, p. 201, likewise the “Annales de Chimie et de Physique,” Phil. Mag., Phil. Trans., Comptes Rendus, more especially, as well as the “Bibl. Univ.” and the “Mem. de la Soc. de Genève,” at which latter place he was born in 1801.

For Jean Jacques d’Ortons de Mairan, consult “Mém. de Paris” for the years 1726, 1731–1734, 1747, 1751, also abridgments of the Phil. Trans. by Hutton, Vol. VII. p. 637, and by Baddam, 1745 ed., Vol. IX. pp. 490–497.

For W. Derham (1657–1735) consult also “Nouv. Biog. Gen.” (Hœfer), Vol. XIII. p. 712; the Phil. Trans. unabridged, Vol. XXIV. for 1704–1705, pp. 2136–2138; Vol. XXXVI. pp. 137, 204, also the following abridgments: Hutton, Vol. V. pp. 258–263; Hy. Jones, Vol. IV. part ii. pp. 290–291; Baddam, Vol. IV. pp. 473–478. In the last-named volume is thus given an account of Mr. Derham’s experiments: “He shows (Phil. Trans., No. 303, p. 2136) that, having consulted what others had writ of magnets, he finds in Grimaldi’s De Lumine et colore that both he and M. De la Hire (Phil. Trans., No. 188) had hit upon the same discovery before him.” Mr. Derham also alludes, more particularly, to the observations of Ridley, Barlow and Dr. Gilbert.

For Claudius--Claes--Arrhenius (1627–1694) Swedish scientist, professor at the Upsal University, consult “La Grande Encycl.,” Vol. III. p. 1107; “Dict. Biog. Suédois,” Vol. XXII. pp. 385–389.

For John Wallis, the celebrated English mathematician (1616–1703), in addition to the above-named Phil. Trans., Vol. XXIII for 1702–1703, p. 1106, consult Phil. Trans., Vol. XII for 1677, No. 135, pp. 863–866 (meteors), also the abridged editions as follows: Hutton, Vol. IV. pp. 196, 639, 655; Hy. Jones, Vol. IV. part ii. p. 286; Baddam, London, 1739, Vol. III. p. 228 and Vol. IV. pp. 100–104 (mariner’s compass); “Nouv. Biog. Gen.” (Hœfer), Vol. XLVI. p. 530.

AURORA AUSTRALIS, OR SOUTHERN POLAR LIGHT

The earliest account of this phenomenon was given by Don Antonio de Ulloa, as will be seen under date A.D. 1735–1746.

REFERENCES.--W. L. Krafft, “Observation,” etc., in Acta Acad. Petropol. for 1778, Part I. Hist., p. 45; Phil. Trans., XLI. pp. 840, 843; XLVI. pp. 319, 345; Chr. Hansteen, “On the Polar Lights,” London, 1827.

ZODIACAL LIGHT

This phenomenon, from its occasional faint resemblance to and association with the auroras, would seem to deserve mention here, though none of the conjectures formed, more particularly by Cassini, Euler, Mairan, Kepler, Laplace, Fatio de Duiller, Schubert, Poisson, Olmsted, Biot, Herschel, Delambre, Olbers or Sir Wm. Thomson attribute to it any electric or magnetic origin.

In the Report of the Proceedings of the Reale Istituto Lombardo, 1876, however, appears the account of many observations confirmed by M. Serpieri which “demand absolutely” the conclusion that the zodiacal light “is an electrical aurora preceding and following the sun round the earth.”

Angstrom asserted that he observed the auroral line in the spectrum of the zodiacal light, and Lewis saw the latter during the aurora of May 2, 1877. Humboldt, who observed it (“Cosmos,” 1849, Vol. I. p. 126) in the Andes at an elevation of 13,000 to 15,000 feet, as well as on “the boundless grassy plains, the Llanos of Venezuela, and on the seashore, beneath the ever-clear sky of Cumana,” believes it to be caused by “a very compressed annulus of nebulous matter, revolving freely in space between the orbits of Venus and Mars.” In this connection he refers to Arago in the Annuaire for 1832, p. 246, and to a letter published in Comptes Rendus, XVI, 1843, p. 687, from which the following is extracted: “Several physical facts appear to indicate that, in a mechanical separation of matter into its smallest particles, if the mass be very small in relation to the surface, the electrical tension may increase sufficiently for the production of light and heat.”

In Chambers’ “Descript. Astronomy,” p. 257, the historian Nicephorus is credited with first calling attention to the existence of this phenomenon, to which Giovanni Domenico Cassini gave the name of Zodiacal Light, after determining its relations in space during the year 1683 (Mém. de l’Académie, 1730, Tome VIII. pp. 188 and 276), but to Childrey belongs the credit of having given to Europe the first explicit description of this phenomenon at p. 183 of his 1661 “Britannia Baconica.”

REFERENCES.--Sturgeon’s Annals, etc., Vol. II. pp. 140–142; Prof. C. W. Prichett’s paper in Sci. Am. Supp., No. 126, p. 2008, and the conclusions reached by Herr Gronemann (_Archives Néerlandaises_) in Sci. Am. Supp., No. 327, p. 5221; Whewell, “Hist. of the Ind. Sciences,” 1859, Vol. I. p. 531, and Vol. II. p. 609; Tyndall, “Heat as a Mode of Motion,” 1873, pp. 57, 58, 497, 498; J. F. J. Schmidt, “Das Zodiacallicht,” Braunschweig, 1856; the very interesting abstract given in “The Journal of the Brit. Assoc.,” Vol. XII. No. 5, of paper read by Rev. J. T. W. Claridge, F.R.S., Jan. 9, 1902; Houzeau et Lancaster, “Bibl. Générale,” Vol. II. 1882, pp. 763–771; “Pr. Roy. Soc. of Edin.,” XX. pt. 3; C. Wilkes, “Theory of Zod. Light,” Philad., 1857; Phil. Trans., Vol. XXXVIII. p. 249; “Cosmos,” 1849, Vol. I. pp. 126–134; “Anc. Mém. de Paris,” I, VIII and X; J. J. de Mairan, Paris, 1733; “U. S. Japan Expedition,” Vol. III, Washington, 1856.

=A.D. 1684.=--Hooke (Dr. Robert), English natural philosopher (1635–1703), who, in 1677, had succeeded Oldenburg as Secretary to the Royal Society, gives the earliest well-defined plan of telegraphic transmission, in a paper addressed to the Royal Society “showing a way how to communicate one’s mind at great distances ... 40, 100, 120, etc., miles ... in as short a time almost as a man could write what he would have sent.” His apparatus consisted of an elevated framework supporting an open screen, behind which were suspended as many wooden devices, or symbols, such as circles, squares, triangles, etc., as there were letters in the alphabet. In the daytime these devices were drawn up by a rope behind the screen and made visible in the open space, while during the night use was made of torches, lanterns or lights.

Hooke also showed, in 1684, that iron and steel rods can be permanently magnetized by strongly heating them and by rapidly cooling them in the magnetic meridian (“Enc. Brit.” 1857, Vol. XIV. p. 3).

But, what is still more singular, he had, even previous to the above-named date (i. e. in 1667), alluded to the possibility of telephoning, that is, communicating sound through a wire. He thus expresses himself: “And as glasses have highly promoted our seeing, so it is not improbable that there may be found many mechanical inventions to improve our other senses--of hearing, smelling, tasting, touching.... ’Tis not impossible to hear a whisper a furlong’s distance, it having been already done; and perhaps the nature of the thing would not make it more impossible though that furlong should be ten times multiplied. And though some famous authors have affirmed it impossible to hear through the thinnest plates of Muscovy glass, I know a way by which it is easy to hear one speak through a wall a yard thick. It has not been examined how far acoustics may be improved, nor what other ways there may be of quickening our hearing, or conveying sound through other bodies than the air, for that is not the only medium. I can assure the reader that I have, by the help of a distended wire, propagated the sound to a very considerable distance in an instant, or with as seemingly quick a motion as that of light, at least, incomparably swifter than that which at the same time was propagated through the air; and this not only in a straight line, or direct, but in one bended in many angles.”

REFERENCES.--Hooke’s entire paper in Derham’s “Phil. Exp. and Obs.” for 1726, pp. 142–150; Phil. Trans, for 1684; for his observations on atmospheric electricity consult Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. p. 166; “Journal des Savants” for April 1846; “The Posthumous Works of Robert Hooke,” London, 1705, p. 424; “Revue Scientifique,” Mars 15, 1902, p. 351; for a complete list of all his works, consult Ward’s “Lives of the Gresham Professors”; for description of his telegraph and reference to Amontons, etc., see Phil. Mag., Vol. I. pp. 312–316.

=A.D. 1684.=--Sturmy’s “Mariner’s Magazine” for this year, of which a copy can be seen in the library of the British Museum, contains an account of the deviation of the compass and its tendency to give misleading directions on account of local attraction.

REFERENCES.--Chambers’ Journal, Vol. III. No. 60 for Feb. 24, 1855, p. 132, and Vol. XII. No. 300 for Oct. 1, 1859, p. 246; Capt. Sam. Sturmy’s “Magn. Virtues and Tides,” in _Phil. Trans._, No. 57, p. 726, or “Memoirs of the Roy. Soc.,” Vol. I. p. 134; Phil. Trans., abridgments: by Hutton, Vol. II. p. 560, and by Lowthorp, Vol. II. p. 609; “Journal des Sçavans” for 1683, Vol. XI. pp. 267–293.

=A.D. 1684.=--In the “Essayes of Natural Experiments made in the Accademia del Cimento” (Englished by Richard Waller), London, 1684, by direction of the Royal Society, there are given, respectively at pp. 53, 123 and 128–132, accounts of the operation of the magnet in vacuo, details of several magnetical experiments and experiments touching amber as well as other electrical bodies.

=A.D. 1686.=--Maimbourg (Louis), French historian, relates this instance of the employment of the magnet at Chap. VI of the Rev. W. Webster’s translation of his “Histoire de l’Arianisme”: “Whilst Valens (the Roman emperor) was at Antioch ... several pagans of distinction, with the philosophers ... not being able to bear that the empire should continue in the hands of the Christians, consulted privately the demons ... in order to know the destiny of the emperor and who should be his successor.... For this purpose they made a three-footed stool ... upon which, having laid a basin of divers metals, they placed the twenty-four letters of the alphabet around it; then one of these philosophers, who was a magician ... holding in one hand vervain and in the other a ring which hung at the end of a small thread, pronounced ... conjurations ... at which the three-footed stool turning around and the ring moving of itself, and turning from one side to the other over the letters, it caused them to fall upon the table ... which foretold them ... that the Furies were waiting for the emperor at Mimas; ... after which the enchanted ring, turning about again over the letters in order to express the name of him who should succeed the emperor, formed first of all these capital letters, T H E O. After adding a D, to form T H E O D, the ring stopped, and was not seen to move any more, at which one of the assistants cried out ... ‘Theodorus is the person whom the gods appoint for our emperor’” (“History of Christianity,” by the Rev. Henry Hart Milman, London, 1840, Vol. III. p. 120).

Maimbourg’s biography is given at p. 58, Vol. IV. of the “English Encyclopædia.”

=A.D. 1692.=--Dr. Le Lorrain de Vallemont relates, in “Description de l’Aimant,” etc., which he published at Paris, that, after a very severe wind and rain storm during the month of October 1690, the new steeple of the Church of Notre Dame de Chartres was found to be so seriously injured as to necessitate demolition. It was then observed that the iron cross was covered with a heavy coating of rust, which latter proved to be so highly magnetic that a special report upon it was made in the “Journal des Sçavans” by M. de la Hire, December 3, 1691, at the request of Giovanni Dom. Cassini, and of other members of the French Royal Academy.

REFERENCES.--“Journal des Sçavans,” Vols. XX, 1692, pp. 357–364 and Vol. XXXV, 1707, pp. 493–494 for additional accounts of the Church of N. Dame de Chartres by M. de la Hire and M. de Vallemont, and for a review of M. de Vallemont’s work, of which latter pp. 4, 30, 66, 74, 89 to 90 merit special attention.

A.D. 1693.--Gregory (David), an eminent mathematician, who, in 1691, had been made Savilian Professor of Astronomy in Oxford mainly through the influence of Newton and Flamsteed, communicates the result of his observations on the laws of magnetic action.

REFERENCES.--Noad, “Manual of Electricity,” 1859, p. 525, _Phil. Trans._, Vols. XVIII-XXV; “Biog. Générale,” Vol. XXI. p. 902; Ninth “Britannica,” Vol. XI. p. 182; J. J. Fahie, “A History of El. Tel. to the year 1837,” London, 1884, p. 24.

=A.D. 1693.=--In the first volume (Letter IV. pp. 25–28) of the “Memoirs for the Ingenious ...” by J. de la Crosse, are given accounts of several “New experiments on the loadstone; of a needle touch’d with it, and plac’d directly over the needle of a compass; of two Mariner’s Needles hang’d freely over one another, at several distances; of a touch’d steel-ring. Reasons of these experiments. The earth magnetical.”

In explanation of all this, M. de la Hire supposes “that the mass of the earth is a great loadstone, which directs the poles of the same name in all the loadstones and touch’d needles, towards the same place of the earth; so that the two hang’d needles do but remove from this natural position by the particular force they have of driving away each other’s poles of the same name; which force, in a certain degree, is not sufficient to overcome the power of the great loadstone of the earth.”

An account of M. P. de la Hire’s “new sort of a magnetical compass” had already appeared in the Phil. Trans. for 1686–1687, Vol. XVI. No. 188, p. 344.

REFERENCES.--For De la Hire, the following abridgments of the Phil. Trans.: Lowthorp, London, 1722, Vol. II. pp. 620–622; Baddam, London, 1739, Vol. IV. pp. 473–478; Hutton, London, 1809, Vol. III. p. 381; also “The Phil. Hist. and Mem. of the Roy. Acad. at Paris,” by Martyn and Chambers, London, 1742, Vol. II. pp. 273–277; Vol. V. pp. 272–282 and the “Table Alphab. ... Acad. Royale,” by M. Godin, Paris, Vol. II. p. 16 and Vol. X. pp. 164 and 734.

=A.D. 1696.=--Zahn (F. Joannes), prebendary of the Prémontrés Order at Celle near Wurtzburg and provost of the convent of Niederzell, celebrated for his philosophical and mathematical studies, publishes his highly valued “Specula physico-mathematico-historica-notabilium ac mirabilium sciendorum ...” throughout the three folio volumes of which he treats extensively of the wonders of the entire universe.

In his tabulated list of the origin and properties of all the different known gems and stones (Vol. II. chap. vii. p. 55), he states that the loadstone, first discovered at Magnesia in Lydia (Caria--on the Mæander) is heavy, very well shaped, and of a dark colour verging upon blue. The marvellous properties of gems and stones are detailed at pp. 59–73 of the same volume, the fifth paragraph of Chap. VIII treating of the loadstone’s many virtues and admirable qualities, as exemplified in the writings of Guilielmus Gilbertus, Nicolaus Zucchius, Nicolaus Cabæus, Athanasius Kircherus, Eusebius Nierembergius, Laurentius Forerus, Hieronymus Dandinus, Jacobus Grandamicus, Ludovicus Alcazar, Claudius Franciscus Milliet de Chales, as well as of many others.

REFERENCES.--Michaud, “Biog. Univ.,” Vol. XLV. p. 340; Dr. John Thomas, “Universal Pron. Dict.,” 1886, p. 2514; Brunet, “Manuel du Libraire,” Vol. V. p. 1519.

=A.D. 1700.=--Bernoulli (John I), son of Nicolas, the founder of the celebrated family of that name, improves upon Picard’s discovery of the electrical appearance of the barometer, made A.D. 1675, by devising a mercurial phosphorus or mercury shining in vacuo (“Diss. Physica de Mercurio Lucente,” etc., Basel, 1719). This procured the favourable notice of King Frederick I, of Prussia, who rewarded him with a medal. John Bernoulli I (1667–1748) was a member of nearly every learned society of Europe and “one of the first mathematicians of a mathematical age.” His exceedingly valuable memoirs, found in all the scientific transactions of the day, were first collected in their entirety during the year 1742, by Cramer, Professor of Mathematics, and published at Lausanne and Geneva.

“Is it not surprising,” remarks Prof. Robison, in his able article on “Dynamics” (Eighth “Britannica,” Vol. VIII. p. 363), “that, twenty-five years after the publication of Newton’s ‘Principia,’ a mathematician on the Continent should publish a solution in the Memoirs of the French Academy, and boast that he had given the first demonstration of it? Yet, John Bernoulli did this in 1710. Is it not more remarkable that this should be precisely the solution given by Newton, beginning from the same theorem, the 40th I., Prin., following Newton in every step and using the same subsidiary lines? Yet, so it is.” This was five years after he had accepted (1705) the chair of mathematics made vacant by the death of his brother, James I.

BERNOULLI FAMILY

The Bernoulli family is as well known in the history of mathematics, by the distinguished services of eight of its members, as is the Cassini family through the successes achieved by four of its representatives in the development of astronomical studies.

Daniel Bernoulli (1700–1782), second son of John I, constructed a dipping needle, which is described on p. 85 of the Eighth “Britannica,” Vol. XIV, and with which he observed the dip to diminish half a degree during an earthquake in the year 1767. Before Daniel was twenty-four years old he had declined the Presidency of the Academy of Sciences at Genoa, and, at the age of twenty-five, was appointed Professor of Mathematics at St. Petersburg.

John Bernoulli II (1710–1790), youngest of the three sons of John I, gained three prizes from the French Academy of Sciences for Memoirs on the Capstan, on the Propagation of Light and on the Magnet.

John Bernoulli III (1744–1807), grandson of John I, took the degree of Doctor of Philosophy at the age of thirteen, and, when nineteen years old, was appointed Astronomer Royal of Berlin. He published several volumes of travels, in one of which he relates (A. L. Ternant, “Le Télégraphe,” 1881, p. 32) that he saw, in the last-named city, an instrument constructed of five bells, with which all letters of the alphabet could be expressed.

James Bernoulli I (1654–1705), brother of John I, while at London, was introduced into the philosophical meetings of Boyle, Hooke, Edward Stillingfleet and other learned and scientific men. He opened, in 1682, the Collegium Experimentale Physico-Mechanicum for public instruction, but his lasting fame dates from the year 1684, when the great Von Leibnitz published his treatise “De Gravitate Ætheris.” Three years later, in 1687, James occupied the mathematical chair of the University of Basel, made vacant by the death of the learned Megerlin.

REFERENCES.--Whewell, “Hist. of the Inductive Sciences,” 1859, Vol. I. pp. 358–366, 375–380, 393, 430, and Vol. II. pp. 32–39, 42; “Hist. de l’Acad. Royale des Sciences,” 1700–1707; Edin. “Encycl.,” 1813, Vol. III. pp. 464–470; “Med. Library and Historical Journal,” New York, 1903, Vol. I. pp. 270–277.

For Bernoulli family see “Histoire des Sc. Math. et Phys.,” Maxim. Marie, Paris, 1888, Vols. VII-XI; “Geschichte der Mathemathik,” Moritz Canton, Leipzig, 1898, Vol. III. pp. 207–261; “Histoire Générale des Mathématiques,” Chas. Bossut, Paris, 1810, Vol. II. s. 2, as at table, p. 512. See the family tree in “Eng. Cycl.,” Vol. VI. p. 972, and all the Bernoullis at p. 84 of Vol. II, Houzeau et Lancaster’s “Bibl. Gén.,” 1882.

=A.D. 1700.=--Morgagni (Giovanni Battista), while practising medicine at Bologna and at Venice, uses the magnet to remove particles of iron which had accidentally fallen into the eyes, exactly in the same manner as Kirkringius and Fabricius Hildanus had done before him.

REFERENCES.--Maunder’s “Biog. Treasury”; also Beckmann’s “History of Inventions,” Vol. I. p. 44, and biography in Larousse, Vol. XI, as well as in Vol. XVI of the Ninth “Britannica.”

=A.D. 1700.=--Duverney (Joseph Guichard), an eminent French anatomist, knew at this date that the limbs of a frog are convulsed by the electric current (as shown in the “Histoire de l’Académie des Sciences,” 1700, p. 40, and 1742, vol. I. p. 187), and the Italian physician L. Marco Antonio Caldani, assistant to Morgagni, alludes to the “revival of frogs by electrical discharges.”

REFERENCES.--“Ency. Metrop.,” Vol. IV. p. 220; Highton’s “Elect. Tel.”; Fahie, “Hist. of Elec. Tel.,” pp. 175 and 176 and notes; Knight’s “Mech. Dict.,” Vol. II. p. 936; G. H. Browne, London, 1704, and in “Phil. Mag.,” Vol. XVIII. p. 285, also note p. 83 of Ronalds’ “Catalogue.”

=A.D. 1701–1702.=--Le Brun (Pierre), French theologian (1661–1729), publishes his “Histoire Critique des Pratiques Superstitieuses,” wherein he makes mention (Vol. I. p. 294) of the possibility of transmitting intelligence in the manner indicated by the Jesuit Leurechon.

He is also the author of “Lettres qui découvrent l’illusion des philosophes sur la baguette divinatoire,” Paris, 1693 (Larousse’s “Dictionnaire,” Tome X. p. 292).

=A.D. 1702.=--Bion (Nicolas), French engineer and manufacturer of mathematical and astronomical instruments (1652–1733), is the author of “Usage des Astrolabes,” which was shortly after followed by his well-known “Traité de la construction et des principaux usages des instruments de mathématique.” In the preparation of the last named, which was translated into German (Leipzig, 1713, Nuremberg, 1721) as well as into English (London, 1723, 1738), Bion admits the assistance afforded him by Lahire, Cassini and Delisle the younger.

The whole of Book VII (pp. 267–290) of the “Traité,” is devoted to the description of instruments employed in navigation, the compass and the astrolabe in particular, with instructions for ascertaining the declination and variation.

Bion is also the author of “L’Usage des Globes Célestes et Terrestres et des sphères suivant les differents systèmes du monde,” Amsterdam, 1700. Much of the matter, however, is said to have been copied by Bion from Pierre Polinière’s “Expériences de Phisique,” of which latter five editions were printed respectively in 1709, 1718, 1728, 1734 and 1741.

REFERENCES.--“La Grande Encycl.,” Vol. VI. p. 897; Michaud, “Biog. Univ.,” Vol. IV. p. 354; Dr. J. Thomas, “Univ. Pr. Dict.,” 1886, p. 386.

=A.D. 1702.=--Marcel (Arnold), Commissioner of the Navy at Arles, publishes a pamphlet dedicated to the King, and entitled “The Art of Making Signals, both by Sea and by Land,” wherein he affirms that he has “communicated frequently at the distance of two leagues (in as short a space of time as a man could write down and form exactly the letters contained in the advice he would communicate), an unexpected piece of news that took up a page in writing.” The particulars of this invention are, however, wanting.

Marcel reports many well-authenticated instances where, as already mentioned by Mæstro Giulio Cæsare (A.D. 1590), iron bars have become temporarily magnetic by position alone.

REFERENCES.--Snow Harris, “Rudim. Mag.,” I and II. pp. 91, 92; also “Emporium of Arts and Sciences,” 1812, Vol. I. p. 301; Phil. Trans., Vol. XXXVII. p. 294, also the following abridgments: Baddam, Vol. IX, 1745, p. 278; Eames and Martyn, Vol. VI. part. ii. p. 270; Hutton, Vol. VII. p. 540.

=A.D. 1702.=--Kæmpfer (Engelbrecht), German physician and naturalist (1651–1716), describes in his “Amœnitates Exoticæ,” experiments made by him upon the electric torpedo (Leithead, 1837, Chap. XII). He insists that any person may avoid all sensation of the shock by merely holding the breath while touching the animal. This apparently improbable fact has since been confirmed, however, by many scientists; the accurate observations of Mr. Walsh (A.D. 1773) on the subject, reported in the Phil. Trans. for 1773–1774–1775, claiming especial attention (Larousse, “Dict.,” Vol. IX. p. 1144).

=A.D. 1704.=--Amontons (Guillaume), an ingenious mechanician and scientist, exhibits before the royal family of France, and before the members of the Académie des Sciences, his system of communicating intelligence between distant points through the agency of magnifying glasses--telescopes. The “Mémoires de l’Académie,” 1698–1705, contain an account of his many scientific productions.

REFERENCES.--Larousse, “Dict.,” Vol. I. pp. 282–283; Appleton’s “Cyclop.,” Vol. I. p. 432.

=A.D. 1705.=--Witson (Nicholaes), Burgomaster of Amsterdam, announces at p. 56 of his “Noord en Oost Tartarye,” that the nautical compass was in use by the Coreans in the second half of the seventeenth century.

=A.D. 1705.=--Hauksbee (Francis), English natural philosopher and Curator of the Royal Society, makes, before the latter, several experiments on the mercurial phosphorus. He shows that a considerable quantity of light can be produced by agitating mercury in partly exhausted as well as in thoroughly exhausted glass vessels. When the mercury is made to break into a shower, flashes of light are seen to start everywhere “in as strange a form as lightning.”

He also showed light in vacuo produced by rubbing amber and by rubbing glass upon woollen. He says (Priestley, “Hist. and Present State of Electricity,” London, 1775, p. 19) that every fresh glass first gave a purple and then a pale light, and that woollen, tinctured with salt or spirits, produced a new, strong and fulgurating light.

Hauksbee constructed a powerful electrical machine wherein the Von Guericke sulphur globe was replaced by one of glass, as had already been done by Sir Isaac Newton (at A.D. 1675). With it he found that upon exhausting the air, whirling the globe rapidly and placing his hand upon the outside, a strong light appeared upon the interior, and that the light would show itself also upon the outside when air was let into the globe (“Physico-Mech. Exp.,” pp. 12, 14, 26, 32, 34).

The machine, which the celebrated mechanician Leupold had constructed at Leipzig for Mr. Wolfius, only differed from the original one made by Hauksbee in that the glass globe turned vertically instead of horizontally.

Other experiments with coated glass globes, globes of sulphur, etc., are detailed in the “Physico-Mech. Exp.,” as indicated at pp. 21–24 the Priestley work above alluded to. At the last-named page he says: “That Mr. Hauksbee, after all, had no clear idea of the distinction of bodies into electrics and non-electrics appears from some of his last experiments, in which he attempted to produce electrical appearances from metals, and from the reasons he gives for his want of success in those attempts.”

Hauksbee also gave some attention to the study of the laws of magnetic force, and the results published in the Phil. Trans., Vol. XXVII. for 1710–1712, p. 506, giving a law of force varying as the sesqui-duplicate ratio of the distances, were subsequently confirmed by Taylor and by Whiston in the Phil. Trans. for 1721 (Noad, “Manual of Elec.,” 1859, p. 579).

REFERENCES.--Aglave et Boulard, “Lumière Electrique,” Paris, 1882, p. 18; Priestley, “Familiar Intr. to Study of Elec.,” London, 1786, p. 60; Phil. Trans., Vol. XXV. pp. 2327, 2332; Vol. XXVI, 1708–1709, pp. 82–92; Vol. XXIX, 1714–1716, p. 294 (with Brooke Taylor); also the following abridgments: Hutton, Vol. V. pp. 270, 307, 324, 344, 355, 411–416, 452, 509, 528, 696; Jones, Vol. IV. p. 295; Baddam, 1745, Vol. V. pp. 33–37, 41–43, 112, 114–117, 483; Thos. Thomson, “Hist. of the Roy. Soc.,” London, 1812, p. 430; Chemical News, Vol. II. p. 147; Nicolas Desmarets, “Expériences,” etc., Paris, 1754, in “Recueil des Mémoires de l’Acad. des Sciences.”

=A.D. 1705.=--Keill (John), M.A., F.R.S., Savilian Professor of Astronomy, is the author of “Introductio ad Veram Physicam, etc.,” of which other editions appeared in 1725, 1739 and 1741, and a good English translation of which was published at Glasgow in 1776.

The last named is entitled “An Introduction to Natural Philosophy, or Lectures in Physics read in the University of Oxford in the Year 1700.” In Lecture VIII he states: “It is certain that the magnetic attractions and directions arise from the structure of parts; for if a loadstone be struck hard enough, so that the position of its internal parts be changed, the loadstone will also be changed. And if a loadstone be put into the fire, insomuch that the internal structure of the parts be changed or wholly destroyed, then it will lose all its former virtue and will scarce differ from other stones.... And what some generally boast of, concerning effluvia, a subtile matter, particles adapted to the pores of the loadstone, etc., does not in the least lead us to a clear and distinct explication of these operations; but notwithstanding all these things, the magnetick virtues must be still reckoned amongst the occult qualities.”

=A.D. 1706.=--Hartsoeker (Nicolas), Dutch natural philosopher, friend of Christian Huyghens, while Professor of Mathematics at Düsseldorf, writes his “Conjectures Physiques,” four editions of which were published during the three years 1708, 1710 and 1712.

The Tenth Discourse of the Second Book (pp. 140–182) treats of the nature and properties of the loadstone and gives numerous observations concerning magnetical phenomena, which are well illustrated. He says that many ordinary stones have become magnetic after being long exposed to the air, in consequence of iron penetrating them. He believes that the native loadstone is made up of ordinary stone and of iron containing many small bodies through which run magnetic channels; that the latter are held together so strongly as to be disintegrated with difficulty, and that they are filled with a subtile matter which circulates incessantly through and around them.

The First Discourse of the Fourth Book treats of Meteors, and at pp. 91–99 of his “Eclaircissements, ...” published in 1710 he gives further reports of his curious observations on magnetic phenomena.

REFERENCES.--“Journal des Sçavans,” Vol. XXIV for 1696, pp. 649–656.

For particulars of the very celebrated natural philosopher, Christian Huyghens--Hugenius van Zuglichen (1629–1695) above alluded to, consult: the “Vita Hugenii,” prefixed to his “Opera Varia,” published by Van ’Sgravesande in 1724; “Meyer’s Konversations-Lexikon,” Leipzig und Wien, 1895, Vol. IX. pp. 93–94, also the biography, embracing a detailed list of his geometrical, mechanical, astronomical and optical works at pp. 536–538 of the “English Cyclopædia”; Vol. II. of Houzeau et Lancaster, “Bibliog. Générale,” p. 169; “Le Journal des Savants” for May 1834, April 1846, July 1888, April 1896, Feb. 1898, Oct. 1899; “Histoire des Sciences Math. et Phys.,” Maximilien Marie, Paris, 1888, Vol. V. pp. 15–140; “Hist. et Mém. de l’Acad. Roy. des Sc.,” Vol. I. p. 307; Hartsoeker’s biography at pp. 307–308 of the “Engl. Cycl.,” Vol. III, 1867.[49]

=A.D. 1707.=--J. G. S. (not, as many suppose, Jean George Sulzer) publishes “Curious Speculations during Sleepless Nights” 8vo, Chemnitz, wherein appears the first account of the development, by heat, of electricity in the tourmaline, which latter, it is therein stated, was first brought from Ceylon by the Dutch in 1703. Another report of the above appears in the Mémoires de l’Académie des Sciences of Paris for 1717.

REFERENCE.--Beckmann, Bohn, 1846, Vol. I. pp. 86–98.

=A.D. 1708.=--Wall (Dr. William), a prominent English divine, communicates to the Royal Society (Phil. Trans., Vol. XXVI. No. 314, p. 69) the result of his experiments, showing him to have been the first to establish a resemblance of electricity to thunder and lightning.

He found that, upon holding tightly in the hand a large bar of amber and rubbing it briskly against woollen cloths, “a prodigious number of little cracklings was heard, every one of which produced a small flash of light (spark); and that when the amber was drawn lightly through the cloth it produced a spark but no crackling.” He observed that “by holding a finger at a little distance from the amber a crackling is produced, with a great flash of light succeeding it, and, what is very surprising, on its eruption it strikes the finger very sensibly, wheresoever applied, with a push or puff like wind. The crackling is fully as loud as that of charcoal on fire.... This light and crackling seem in some degree to represent thunder and lightning.”

REFERENCES.--Bakewell, “Electric Science,” p. 13; Aglave et Boulard, “Lumière Electrique,” 1882, p. 17; Thos. Thomson, “An Outline of the Sciences of Heat and Electricity,” London, 1830, pp. 314, 463; Thos. Thomson, “Hist. of the Roy. Soc.,” London, 1812, p. 431; see also the following abridgments of the _Phil. Trans._; Hutton, Vol. V. p. 408 and Baddam of 1745, Vol. V. p. 111.

=A.D. 1712.=--The great Japanese Encyclopædia, Wa-Kan-san siü tson-ye, describes the compass, zi-siak-no-fari, at Vol. XV. folio 3, recto (Klaproth, “Lettre à M. de Humboldt,” etc., 1834, p. 107).

=A.D. 1717.=--Leméry (Louis), two years after the death of his distinguished father, Nicolas Leméry, exhibits a stone (the tourmaline) brought from Ceylon, and announces, to the French Académie des Sciences, that it possesses the electrical property of attracting and repelling light bodies after being warmed.

Carl Linnæus (1707–1777) alludes to the experiments of Leméry, in his Flora Zeylanica, and mentions the stone under the name of lapis electricus. (See, for Carl Linnæus, “Thesaurus Litteraturæ Botanicæ,” G. A. Pritzel, Lipsiæ, 1851, pp. 162–169, also “Guide to the Literature of Botany,” by Benj. Daydon Jackson, London, 1881, pp. xxxvi, etc.)

The first scientific examination of the electric properties of the tourmaline was, however, made by Æpinus in 1756, and published in the Memoirs of the Berlin Academy. Æpinus showed that a temperature of between 99½° and 212° F. was necessary for the development of its attractive powers.

Of the electricity of crystals, Gmelin, in his “Chemistry” (Vol. I. p. 319), names the following discoverers: Æpinus (tourmaline)--see A.D. 1759; Canton (topaz)--see A.D. 1753; Brard (axinite)--see A.D. 1787; Haüy (boracite, prehnite, sphene, etc.)--see A.D. 1787; Sir David Brewster (diamond, garnet, amethyst, etc.)--see A.D. 1820; and Wilhelm Gottlieb Hankel (borate of magnesia, tartrate of potash, etc.).

REFERENCES.--Becquerel, “Résumé,” 1858, p. 11; Leithead, “Electricity,” p. 239; “Ph. Hist. and Mem. of Roy. Ac. of Sc. at Paris,” London, 1742, Vol. V. p. 216; “Journal des Sçavans,” Vol. LXX for 1721, pp. 572–573 on the tourmaline.

=A.D. 1720.=--Grey--Gray (Stephen), a pensioner of the Charter House and Fellow of the Royal Society, makes known through his first paper in the Phil. Trans. the details of the important line of investigation which finally led to the discovery of the principle of electric conduction and insulation as well as to the fact, not the principle, of induction (see Æpinus, A.D. 1759). Thus, to Grey is due the credit of having laid the foundation of electricity as a science.

He proved that electricity can be excited by the friction of feathers, hair, linen, paper, silk, etc., all of which attract light bodies even at a distance of eight or ten inches. He next discovered that electricity can be communicated from excited bodies to bodies incapable of ready excitation. When first suspending a hempen line with pack threads he could not transmit electricity, but when suspending the line with silken threads he transmitted the electrical influence several hundred feet. The latter he did at the suggestion of his friend Granville Wheeler--Wheler--(not Checler, as Aglave et Boulard have it in “Lumière Electrique,” p. 20), thinking that “silk might do better than pack thread on account of its smallness, as less of the virtue would probably pass off by it than by the thickness of the hempen line which had been previously used.” They both tried experiments with longer lines of pack thread, but failed, as they likewise did after substituting thin brass wire for the thread. This afterwards led to the discovery of other insulating substances, like hair, resin, etc. During the months of June 1729, and August 1730, Grey and Wheeler succeeded in transmitting electricity through pack thread supported by silken cords a distance of 765 feet, and through wire at a distance of 800–886 feet.

Grey demonstrated also that electric attraction is not proportioned to the quantity of matter in bodies, but to the extent of their surface, and he likewise discovered the conducting powers of fluids and of the human body. Of the cracklings and flashes of light he remarks: “And although these effects are at present but in minimis, it is probable, in time, there may be found out a way to collect a greater quantity of the electric fire, and consequently to increase the force of that power, which by several of those experiments, if we are permitted to compare great things with small, seems to be of the same nature with that of thunder and lightning” (Phil. Trans., abridgment of John Martyn, Vol. VIII. p. 401).

Stephen Grey may be said to have continued his experiments while lying upon his death-bed, for, unable to write, he dictated to the last, as best he could, the progress he had made in his studies to Dr. Mortimer, the Secretary of the Royal Society (Phil. Trans., 1735–1736, Vol. XXXIX. p. 400).

Grey’s own description of a new electric planetarium deserves reproduction here: “I have lately made several new experiments upon the projectile and pendulous motions of small bodies by electricity; by which small bodies may be made to move about larger ones, either in circles or ellipses, and those either concentric or excentric to the centre of the large body about which they move, so as to make many revolutions about them. And this motion will constantly be the same way that the planets move around the sun, viz. from the right hand to the left, or from west to east. But these little planets, if I may so call them, move much faster in their apogeon than in the perigeon part of their orbits, which is directly contrary to the motion of the planets around the sun.” To this should be added the following description of the manner in which these experiments can be made: “Place a small iron globe, of an inch or an inch and a half in diameter, on the middle of a circular cake of rosin, seven or eight inches in diameter, greatly excited; and then a light body, suspended by a very fine thread, five or six inches long, held in the hand over the centre of the cake, will, of itself, begin to move in a circle around the iron globe, and constantly from west to east. If the globe is placed at any distance from the centre of the circular cake, it will describe an ellipse, which will have the same excentricity as the distance of the globe from the centre of the cake. If the cake of rosin be of an elliptical form, and the iron globe be placed in the centre of it, the light body will describe an elliptical orbit of the same excentricity with the form of the cake. If the globe be placed in or near one of the foci of the elliptical cake, the light body will move much swifter in the apogee than in the perigee of its orbit. If the iron globe is fixed on a pedestal an inch from the table, and a glass hoop, or a portion of a hollow glass cylinder, excited, be placed around it, the light body will move as in the circumstance above mentioned, and with the same varieties.”

REFERENCES.--Priestley, “Hist. and Present State of Elec.,” 1775, pp. 26–42, 55–63; and “A New Universal History of Arts and Sciences,” Electricity, Vol. I. p. 460; Saturday Review, August 21, 1858, p. 190; Wilson, “Treatise,” 1752, Section IV. prop. i. p. 23, note; Phil. Trans., Vol. XXXI. p. 104; Vol. XXXVII. pp. 18, 227, 285, 397; Vol. XXXIX. pp. 16, 166, 220, also the following abridgments: Hutton, Vol. VI. p. 490; Vol. VII. pp. 449, 536, 566; Vol. VIII. pp. 2, 51, 65, 316; Reid and Gray, London, 1733, Vol. VI. pp. 4–17 (Granville Wheler); Eames and Martyn, Vol. VI. part ii. pp. 7, 9, 15, and Part IV. p. 96; Vol. VII. pp. 18–20, 231; John Martyn, Vol. VIII. part ii. pp. 397, 403, 404 (Dr. C. Mortimer); Baddam, Vol. IX, 1745, pp. 145–160, 244, 272, 340, 497; “An Outline of the Sciences of Heat and Electricity,” Thomas Thomson, London, 1830, p. 344; and Thos. Thomson’s “Hist. of the Roy. Soc.,” London, 1812, p. 431; Weld, “Hist. of Roy. Soc.,” Vol. I. p. 466; “A course of lectures on Nat. Philos. and the Mechanical Arts,” by Thos. Young, London, 1807, Vol. II. p. 417; “Hist. de l’Académie des Sciences,” 1733, p. 31; “Jour. Litter.” de 1732, à la Haye, pp. 183, 186, 187, 197; “Hist. de l’Académie Royale de Berlin,” 1746, p. 11; “Journal des Sçavans,” Vol. CXXV for 1741, pp. 134–141, and Vol. CXXVI for 1742, pp. 252–263. For Granville Wheeler, consult Phil. Trans., Vol. XLI. pp. 98, 118, also the following abridgments: Hutton, Vol. VIII. pp. 306–320; John Martyn, Vol. VIII. part ii. pp. 406, 412, 415. For Dr. C. Mortimer, consult Phil. Trans., Vol. XLI. p. 112 and John Martyn’s abridgments, Vol. VIII. part ii. pp. 404–412.

=A.D. 1721.=--Taylor (Brooke), LL.D., F.R.S. (1685–1731), an eminent English mathematician, past Secretary of the Royal Society, and one of the ablest geometers of his time--“the only one who, after the retreat of Newton, could safely enter the lists with the Bernoullis”--publishes his “Experiments on Magnetism” in Phil. Trans., No. 368.

In order to arrive at a proper determination of the laws of magnetic force, Dr. Taylor--and also Whiston and Hauksbee--according to Sir David Brewster, considered “the deviation of a compass needle from the meridian, produced by the action of a magnet at different distances; and the conclusion which they all drew from their experiments was that the magnetic force was proportional to the sines of half the arcs of deviation, or nearly in the inverse sesqui-duplicate ratio of the distance, or as the square roots of the fifth powers of the distances. Dr. Taylor had already come to the conclusion that the force was different in various magnets, and decreased quicker at great distances than at small ones, an experimental fact, as shown by Sir W. S. Harris, ‘Rud. Mag.,’ Part III. p. 224.”

In Dr. Thomas Thomson’s “History of the Royal Society” we read, however (p. 461), that Brooke Taylor, and after him Musschenbroek, attempted without success to determine by experiment the rate at which the magnetic attractions and repulsions vary. This rate was successfully investigated by the subsequent experiments of Lambert, Robison and Coulomb. The nature of magnetic curves was first satisfactorily explained by Lambert, Robison and Playfair. Brooke Taylor gave four poles to a wire by touching it at one end or at various parts, as indicated in Phil. Trans., Vol. XXIX. p. 294, and Vol. XXXI. p. 204.

REFERENCES.--Whewell, “Hist. of the Ind. Sciences,” 1859, Vol. I. pp. 359, 375; Vol. II. p. 31; “General Biog. Dict.,” London, 1816, Vol. XXIX. pp. 163–166; Phil. Trans. for 1714–1716, Vol. XXIX. p. 294 and the following abridgments: Hutton, Vol. VI. p. 528; Reid and Gray, Vol. VI. pp. 17, 159; Hy. Jones, Vol. IV. part ii. p. 297; Eames and Martyn, Vol. VI. part ii. p. 253.

=A.D. 1722.=--Graham (George), a celebrated optician and instrument maker in London, is the first to distinctly make known the diurnal and horary variations of the magnetic needle, traces of which had been merely recognized as facts by Gellibrand, in 1634, and by the Missionary Father Guy-Tachard at Louvo, in Siam, during 1682. He finds that its northern extremity begins to move westward at about seven or eight o’clock in the morning, and continues to deviate in that direction until about two o’clock in the afternoon, when it becomes stationary; it soon begins to return to the eastward and becomes again stationary during the night. Graham made nearly a thousand observations, between the 6th of February and the 12th of May, 1722, and found that the greatest westerly variation was 14° 45’, and the least 13° 50’; in general, however, it varied between 14° and 14° 35’, giving 35’ for the amount of the daily variation.

Graham’s discovery--afterwards amplified by Anders Celsius (A.D. 1740)--attracted but little attention until 1750, when the subject was ably taken up by Wargentin, Secretary to the Swedish Academy of Sciences. Between 1750 and 1759 Mr. John Canton made about 4000 observations on the same subject, and was followed by the Dutch scientist Gerard van Swieten, the favourite pupil of Boerhaave, with like results.

As Dr. Lardner states (“Lectures on Science and Art,” 1859, Vol. II. p. 115), the same phenomenon has been observed more recently by Col. Beaufoy (at A.D. 1813), by Prof. Hansteen (at A.D. 1819) and by many others. He further states that Cassini, who observed the diurnal variation of the needle at Paris, found that neither the solar heat nor light influenced it, for it was the same in the deep caves constructed under the Observatory in Paris, where a sensibly constant temperature is preserved, and from which light is excluded, as at the surface. In northern regions these diurnal changes are greater and more irregular; while, toward the line, their amplitudes are gradually diminished until at length they disappear altogether.

It was Graham who first entertained the idea of measuring the magnetic intensity through the vibrations of the needle, a method subsequently used by Coulomb, and which many believe was invented by the latter. From the observations made by Humboldt and by Gay-Lussac in this manner, Biot has reduced the variation of intensity in different latitudes.

REFERENCES.--“Am. Journal Science,” Vol. XXX. p. 225; Walker, “Magnetism,” Chap. II; Fifth Dissertation of the Eighth “Britannica,” Vol. I. p. 744; also Phil. Trans. 1724–1725, Vol. XXXIII. p. 332, and pp. 96–107 (“An Account of Observations Made of the Horizontal Needle at London, 1722–1723, by Mr. George Graham”) and the following abridgments: Reid and Gray, Vol. VI. pp. 170, 187; Hutton, Vol. VII. pp. 27, 94; Vol. IX. p. 495; Eames and Martyn, Vol. VI. part ii. pp. 28, 280, 290; Baddam, 1745, Vol. VIII. p. 20; John Martyn, Vol. X. part ii. p. 698; An de chimie for 1749, Vol. XXV. p. 310.

=A.D. 1725.=--Horrebow--Horreboe--(Peter), was a Danish physicist (1679–1764), who studied medicine for a time and then became a pupil of the celebrated mathematician and astronomer Olaus Rœmer (1644–1710, best known by his discovery of the finite velocity of light), whom he succeeded in the University of Copenhagen.

His earliest work, “Clavis Astronomiæ,” first appeared during 1725, but it is only in the second and enlarged new edition of it in Horrebow’s “Operum Mathematico-Physicorum,” Havn. 1740, Vol. I. p. 317, that will be found the passage (s. 226) in which the luminous process of the sun is characterized as a perpetual northern light. Humboldt, who mentions the fact (“Cosmos,” 1859, Vol. V. p. 81) suggests that a comparison be made of Horrebow’s statement with the precisely similar views held by Sir William Herschel (1738–1822) and Sir John Frederick William Herschel (1792–1871). He says that Horrebow, who did not confound gravitation with magnetism, was the first who thus designated the process of light produced in the solar atmosphere by the agency of powerful magnetic forces (“Mémoires de Mathématiques et de Physique, présentés à l’Académie Royale des Sciences,” Vol. IX. 1780, p. 262; Hanow, in Joh. Dan. Titius’s “Gemeinützige Abhand. über natür. Dinge,” 1768, p. 102), and, with reference to the Herschels he thus expresses himself: “If electricity, moving in currents, develops magnetic forces, and if, in accordance with an early hypothesis of Sir Wm. Herschel (Phil. Trans. for 1795, Vol. LXXXV. p. 318; John Herschel, “Outlines of Astronomy,” p. 238; also, Humboldt, “Cosmos,” Vol. I. p. 189), the sun itself is in the condition of a perpetual northern light (I should rather say of an electro-magnetic storm) we should seem warranted in concluding that solar light transmitted in the regions of space by vibrations of ether, may be accompanied by electro-magnetic currents” (“Dict. of Nat. Biog.,” for John and William Herschel, Vol. XXVI. pp. 263–274).

REFERENCES.--Larousse, “Dict. Univ.,” Vol. IX. p. 397; Wolf, “Hist. Ordbog.,” Vol. VII. pp. 194–199; Nyerup, “Univ. Annalen”; Houzeau et Lancaster, “Bibliographie,” 1882, Vol. II. p. 166.

Three of the children of Peter Horrebow, almost equally distinguished for their learning, are: Nicolas Horrebow (1712–1760), who made physical and astronomical observations in Iceland and published an able report thereon during 1752; Christian Horrebow (1718–1776), who succeeded his father in 1753 as astronomer in the Copenhagen University and who wrote several important scientific treatises; and Peter Horrebow (1728–1812), who was professor of mathematics and philosophy, and published works on geometry, meteorology and astronomy.

Much of interest concerning the above will also be found in the “Abstracts of Papers ... Roy Soc.,” Vol. II. pp. 208, 249, 251, and in the “Catalogue of Sc. Papers ... Roy. Soc.,” Vol. III. pp. 322–328; Vol. VI. p. 687; Vol. VII. p. 965.

=A.D. 1726.=--Wood (John), an English architect of considerable repute, is said to have shown that the electric fluid could be conveyed through wires a long distance, and, during the year 1747, one of the earliest applications of Wood’s discovery was made by Dr. William Watson (see A.D. 1745), who extended his experiments over a space of four miles, comprising a circuit of two miles of wire and an equal distance of ground.

REFERENCES.--Alexander Jones, “Sketch of the Elect. Teleg.,” New York, 1852, p. 7; Charles F. Briggs, “Story of the Telegraph,” 1858, p. 18.

=A.D. 1729.=--Hamilton (James), who became sixth Earl of Abercorn--also called Lord Paisley--publishes “Calculations and Tables relating to the attractive virtue of loadstones ...” containing very valuable data and wherein he is the first to give the true law of the lifting capacity of magnets, as follows: “The principle upon which these tables are formed is this: That if two loadstones are perfectly homogeneous, that is if their Matter be of the same specifick parity, and of the same virtue in all parts of one stone, as in the other; and that like parts of their surfaces are cap’d or arm’d with iron; then the weights they sustain will be as the squares of the cube roots of the weights of the loadstones; that is, as their surfaces.”

Gilbert treats of armed loadstones, Book II. chaps. xvii-xxii. In connection with the increased energy which magnets acquire by being armed, that is, fitted with a cap of polished iron at each pole, Dr. Whewell remarks that it is only at a later period any notice was taken “of the distinction which exists between the magnetical properties of soft iron and of hard steel; the latter being susceptible of being formed into artificial magnets, with permanent poles; while soft iron is only passively magnetic, receiving a temporary polarity from the action of a magnet near it, but losing this property when the magnet is removed. About the middle of the last century various methods were devised of making artificial magnets, which exceeded in power all magnetic bodies previously known” (“Hist. of the Ind. Sc.,” 1859, Vol. II. p. 220).

Hamilton alludes to a loadstone weighing 139 grains, with a lifting power of 23,760 grains! We have referred, amongst others, to the loadstone belonging to Sir Isaac Newton at A.D. 1675, and to the wonderful collection belonging to Mr. Butterfield at A.D. 1809. A loadstone weighing twelve ounces, capable of lifting sixty pounds of iron, is referred to in Terzagus, “Musæum Septalianum,” 1664, p. 42, while another weighing two and a half grains and lifting 783 grains is mentioned at p. 272, Vol. III. of the “Records of General Science”; and Salviatus (“Dialogues of Galileo,” Dial. III) alludes to one in the Academy of Florence which, unarmed, weighed six ounces and could lift but two ounces, but when armed had a lifting power of 160 ounces. At pp. 317–318, Part III of Nehemiah Grew’s “Musæum Regalis Societatis,” London, 1681--also 1686--allusion is made to a loadstone found in Devonshire, weighing about sixty pounds, which moved a needle nine feet distant. Grew then refers to Athan. Kircher and to Vincent Leotaud as having published what is said of the loadstone by Gilbert and others, and he likewise states: “Those that travail through the vast deserts of Arabia, have also a needle and a compass whereby they direct themselves in their way, as Mariners at sea [Majoli, ‘Colloquia’]; the power of the magnet dependeth not upon its bulk--the smaller being usually the stronger....”

REFERENCES.--Phil. Trans. for, 1729–1730, No. 412, Vol. XXXVI. p. 245, and for July 1888, also Hutton’s abridgments, Vol. VII. p. 383; V. T. M. Van der Willigen, “Arch. du Musée Teyler,” 1878, Vol. IV; Jacobi Rohaulti, “Physica,” 1718, Part III. cap. 8, p. 403, or the English translation by Dr. Clarke, 1728, Vol. II. p. 181; P. W. Hacker, “Zur theorie des magnetismus,” Nürnberg, 1856; Ath. Kircher, “Magnes. ...” 1643, lib. i. part ii. p. 63; Daniel Bernoulli, “Acta Helvetica,” 1758, Vol. III. p. 223; Nic. Cabæus “Philosophia Magnetica,” 1629, lib. iv. cap. 42, p. 407; Kenelme Digby, “The Nature of Bodies,” 1645, Chap. XXII. p. 243; “Dict. of Nat. Biog.” Vol. XXIV. p. 185.

=A.D. 1729–1730.=--Savery (Servington), English mechanician, succeeds in imparting magnetism to hard steel bars three-fourths of an inch square and sixteen inches long, by fitting one bar with an armature at each end and touching other bars with it whilst held in the magnetic meridian in the line of the inclined needle.

It was shown by Savery that his artificial magnets were preferable to loadstones. The first recorded attempt to make artificial magnets is credited to one John Sellers, believed to be the author of “The Practical Navigator,” of which the earliest edition appeared in 1669, and of “The Coasting Pilot,” published about 1680. An “Answer to Some Magnetical Inquiries Proposed in (the preceding) No. 23, pp. 423–424,” will be found in Phil. Trans. for 1667, Vol. II. pp. 478–479 and in the following abridgments: Baddam, 1745, Vol. I. p. 86; Hutton, Vol. I. p. 166 (as of No. 26, p. 478); John Lowthorp, Vol. II. p. 601. Reference is likewise made to this invention of Sellers at Vol. I. p. 86 of the “Memoirs of the Royal Society,” London, 1739, and in a paper by Réaumur, in the “Mémoires de l’Académie Française” for the year 1723.

REFERENCES.--Savery, “Magnetical Observations and Experiments,” also Phil. Trans., Vol. XXXVI. pp. 295–340; and the following abridgments: Hutton, Vol. VII. p. 400; Reid and Gray, Vol. VI. p. 166; Eames and Martyn, Vol. VI. p. 260; Baddam, 1745, Vol. IX. p. 57; Geo. Adams, “Essay on Electricity,” 1785, p. 451.

=A.D. 1731.=--On the 25th of November the Royal Society were honoured by a visit from the Prince of Wales and the Duke of Lorraine, the last named being enrolled as a member during the evening. Experiments were performed “On the strength of Lord Paisley’s loadstone,” “On Dr. Frobenius’s phlogiston,” and “On the electrical observations of Mr. Stephen Grey.” These experiments which, it is said, “succeeded notwithstanding the largeness of the company,” showed the facility with which electricity passes through great lengths of conductors and are worth noting as being the first of their nature.

=A.D. 1732.=--Régnault (Le Père Noël) gives in “Les Entretiens Physiques,” etc., Vol. I. Nos. 15 and 16, the tables of the declination at Paris from the years 1600–1730, and treats at length of the merits of the loadstone and of the magnetic needle.

In Vols. II, IV and V he discourses about the extent of the magnetic fluid and explains the phenomena of meteors, St. Elmo’s fire, thunder, etc., besides recording the experiments of Grey, Dufay and others.

=A.D. 1733.=--Dufay (Charles François de Cisternay), French scientist and superintendent of the Jardin du Roi, now the Jardin des Plantes, of Paris (in which latter position he was succeeded by Buffon), communicates to the French Academy of Sciences the history of electricity brought down to the year 1732 (Dantzig Memoirs, Vol. I. p. 195).

He is said to have originated the theory of two kinds of electricity permeating matter and producing all the known phenomena of attraction, repulsion and induction, though the honour of this important discovery should be shared by M. White, who was associated at one time with Stephen Grey and who, it appears, independently discovered the fact while in England. Dufay thus announces his discovery: “... there are two kinds of electricity, very different from one another, one of which I call vitreous (positive) and the other resinous (negative) electricity. The first is that of glass, rock crystal, precious stones, hairs of animals, wool and many other bodies. The second is that of amber, copal, gum-lac, silk, thread, paper and a vast number of other substances. The characteristics of these two electricities are that they repel themselves and attract each other. Thus a body of the vitreous electricity repels all other bodies possessed of the vitreous, and, on the contrary, attracts all those of the resinous electricity. The resinous also repels the resinous and attracts the vitreous. From this principle one may easily deduce the explanation of a great number of the phenomena; and it is probable that this truth will lead us to the discovery of many other things” (see Franklin, at A.D. 1752, and Symmer, at A.D. 1759).

Upon repeating Grey’s experiments, Dufay observed, amongst other things, that, by wetting pack thread, electricity was more readily transmitted through it, and he was enabled thus easily to convey the fluid a distance of 1256 feet, though the wind was high and although the line made eight returns.

REFERENCES.--Fontenelle, “Eloge”; Priestley, “History and Present State of Electricity,” 1775, Period IV. pp. 43–54; Sturgeon, Lectures, 1842, p. 23; “An Epitome of El. and Mag.,” Philad., 1809, p. 29; Mém. de l’Acad. Royale des Sciences for 1733, pp. 23, 28, 76, 83, 233–236, 251, 252, 457; also for the years 1734, pp. 303, 341, and 1737, pp. 86, 307; _Phil. Trans._, Vol. XXXVIII. p. 258; also the following abridgments: Hutton, Vol. VII. p. 638; John Martyn, Vol. VIII. part ii. p. 393; Baddam, Vol. IX. p. 497; Thos. Thomson, “An Outline of the Sciences of Heat and Electricity,” London, 1830, p. 344 and Thos. Thomson, “Hist. of the Roy. Soc.,” London, 1812, p. 432; “Electricity in the Service of Man,” R. Wormell (from the German of Dr. Urbanitzky), London, 1900, p. 14; “Journal des Sçavans,” Vol. XCIII for 1731, pp. 383–388; Vol. C for 1733, p. 244; Vol. CIV for 1734, p. 479; Vol. CXII for 1737, p. 65; Vol. CXV for 1738, p. 173; Vol. CXXIX for 1743, p. 501.

=A.D. 1733.=--Winckler (Johann Heinrich), a philosopher of Wingendorf, Saxony, and Professor of Languages in the University of Leipzig, first uses a fixed cushion in the electric machine for applying friction instead of by means of the hand, and is, by many, believed to have been the first to suggest the use of conductors as a means of protection against lightning (see B.C. 600).

In March 1745, Winckler read a paper before the Royal Society, in which he describes machines for rubbing tubes and globes, also a contrivance with which he can give his globes as many as 680 turns in a minute. Priestley states that the German electricians generally used several globes at a time and that they could excite such a prodigious power of electricity from “globes, whirled by a large wheel and rubbed with woollen cloth or a dry hand, that, if we may credit their own accounts, the blood could be drawn from the finger by an electric spark; the skin would burst and a wound appear, as if made by a caustic.”

During the year 1746 Winckler made use of common electricity for telegraphic communications by the discharge of Leyden jars through very long circuits, in some of which the River Pleisse formed a part, and it may be added that Joseph Franz had previously discharged the contents of a jar through 1500 feet of iron wire while in the city of Vienna.

REFERENCES.--Phil. Trans., Vol. XLIII. p. 307; Vol. XLIV. pp. 211, 397; Vol. XLV. p. 262; Vol. XLVII. p. 231; Vol. XLVIII. p. 772; also following abridgments: Hutton, Vol. IX. pp. 74, 109, 251, 345, 494; Vol. X. pp. 197, 529; John Martyn, Vol. X. part ii. pp. 269, 273, 327, 345, 399; Priestley, 1775, on the discoveries of the Germans, pp. 70–77; “Thoughts on the Properties,” etc., Leipzig, 1744, pp. 146, 149.

=A.D. 1733.=--Brandt (Georg), Swedish chemist, gives in the “Memoirs of the Academy” of Upsal an account of the experiments made by him to show the possibility of imparting magnetism to substances which are not ferruginous. He proved it in the case of the metal cobalt, and during the year 1750 the able discoverer of nickel, Axel. F. de Cronstedt, showed that the latter is likewise susceptible of this property.

REFERENCES.--Thomas, “Dict. of Biog.,” 1871, Vol. I. p. 428; English Cyclopædia (Biography Supplement), 1872, p. 423.

=A.D. 1734.=--Polinière (Pierre), French physician and experimental philosopher (1671–1734), member of the Society of Arts, entirely revises the fourth edition of his “Expériences de Phisique” originally issued in 1709. While the second volume contains but a short chapter relative to electricity, meteoric disturbances, etc., the remainder of the work gives very curious and interesting experiments with the loadstone, making allusion to the observations of John Keill, besides treating of the declination of the needle, etc.

REFERENCES.--“New Gen. Biog. Dict.,” London, 1850, Vol. XI. p. 177; Moréri, “Grand Dict. Hist.”; “Biog. Univ.” (Michaud), Vol. XXXIII. p. 637; “Nouv. Biog. Gén.” (Hœfer), Vol. XL. p. 614; Chaudon, “Dict. Hist. Univ.”

=A.D. 1734.=--Swedenborg (Emanuel), founder of the Church of New Jerusalem, details in his “Principia Rerum Naturalium,” etc., the result of experiments and sets forth the laws relating to magnetic and electric forces and effects. The first explicit treatise upon the close relationship existing between magnetism and electricity was, however, written fourteen years later by M. Laurent Béraud (1703–1777), Professor of Mathematics at the College of Lyons. Both Swedenborg and Béraud recognized the fact that it is, as Fahie expresses it, the same force, only differently disposed which produces both electric and magnetic phenomena.

In “Results of an Investigation into the MSS. of Swedenborg,” Edinburgh, 1869, p. 7, No. 16, Dr. R. L. Tafel makes following entry:

“A treatise on the magnet, 265 pages text and 34 pages tables, quarto. This work is a digest of all that had been written up to Swedenborg’s time on the subject, with some of his own experiments. According to the title page, Swedenborg had intended it for publication in London during the year 1722.”

The “Principia Rerum Naturalium” is the first volume of Swedenborg’s earliest great work, “Opera Philosophica et Mineralia,” originally published in Leipzig and Dresden 1734, which has justly been pronounced a very remarkable cosmogony. In the “Principia” Part I. chap. ix., is to be found his treatment of what he calls the second or magnetic element of the world; in Part III. chap. i. he gives a comparison of the sidereal heaven with the magnetic sphere, but he devotes the whole of Part II to the magnet in following chapters:

I. On the causes and mechanism of the magnetic forces;

II. On the attractive forces of two or more magnets, and the ratio of the forces to the distances;

III. On the attractive forces of two magnets when their poles are alternated;

IV. On the attractive forces of two magnets when their axes are parallel or when the equinoctial of the one lies upon the equinoctial of the other;

V. On the disjunctive and repulsive forces of two or more magnets when the cognomical or inimical poles are applied to each other;

VI. On the attractive forces of the magnet and of iron;

VII. On the influence of the magnet upon ignited iron;

VIII. On the quantity of exhalations from the magnet and their penetration through hard bodies, etc.;

IX. On the various modes of destroying the power of the magnet; and on the chemical experiments made with it;

X. On the friction of the magnet against iron, and on the force communicated from the former to the latter;

XI. On the conjunctive force of the magnet, as exercised upon several pieces of iron;

XII. On the operation of iron and of the magnet upon the mariner’s needle; and on the reciprocal operation of one needle upon another;

XIII. On other methods of making iron magnetical;

XIV. The declination of the magnet calculated upon the foregoing principles;

XV. On the causes of the magnetic declination;

XVI. Calculation of the declination of the magnet for the year 1722, at London.

REFERENCES.--Béraud, “Dissertation,” etc., Bordeaux, 1748; also Priestley, 1775, p. 191; “Biographie Universelle,” Vol. III. p. 687; “Biog. Génér.,” Vol. XLIV. pp. 690–703; Daillant de la Touche, “Abrégé des ouvrages de Swedenborg,” 1788; J. Clowes, “Letters on the writings of Swedenborg,” 1799; “Svenskt Biografiskt Handlexikon,” Herm. Hofberg, Stockholm, pp. 368–369; “Swedenborg and the Nebular Hypothesis,” Magnus Nyrén, astronomer at Observatory of Pulkowa, Russia, translated from the “Viertel jahrschrift der Astronomischen Gesellschaft,” Leipzig, 1879, p. 81, by Rev. Frank Sewall.

=A.D. 1735–1746.=--Ulloa (Don Antonio de), Spanish mathematician, who left Cadiz May 26, 1735, for South America, whither he was sent with Condamine and other French Academicians, as well as with Spanish scientists, to measure a degree of the meridian, returned to Madrid July 25, 1746, and shortly after gave an account of his experiences during an absence of eleven years and two months.

In his “Voyage Historique de l’Amérique Méridionale,” Amsterdam and Leipzig, 1752, he speaks (Vol. I. pp. 14–18 and Vol. II. pp. 30–31, 92–94, 113, 123, 128) of the defective magnetic needles given him as well as of the means of correcting them, and he details at great length the variations of the needle observed during the voyage. He also alludes to the variation charts of Dr. Halley and to the alterations therein made by advice of William Mountaine and Jacob Dooson--James Dodson--of London, as well as to the methods of ascertaining the variation of the magnetic needle pointed out both by Manuel de Figueyredo, at Chaps. IX-X of his “Hidrographie ou Examen des Pilotes,” printed at Lisbon in 1608, and by Don Lazare de Flores at Chap. I, part ii. of his “Art de Naviguer,” printed in 1672. The latter, he says, asserts, in Chap. IX, that the Portuguese find his method so reliable that they embody it in all the instructions given for the navigation of their vessels.

At pp. 66, 67, Chap. X of vol. ii. Ulloa makes the earliest recorded reference to the aurora australis, as follows: “At half-past ten in the evening, and as we stood about two leagues from the island of Tierra de Juan Fernandez, we observed upon the summit of a neighbouring mountain a very brilliant and extraordinary light.... I saw it very distinctly from its inception, and I noticed that it was very small at first, and gradually extended until it looked like a large, lighted torch. This lasted three or four minutes, when the light began to diminish as gradually as it had grown, and finally disappeared.”

Incidentally, it may be stated here that the very learned Dr. John Dalton reported having seen the aurora australis in England, and to have besides observed the aurora borealis as far as 45° latitude south (see accounts in Philosophical Transactions, Philosophical Magazine, Manchester Transactions and Nicholson’s Journal), while Humboldt remarks (“Cosmos,” 1849, Vol. I. p. 192, note) that in south polar bands, composed of very delicate clouds, observed by Arago, at Paris, on the 23rd of June, 1844, dark rays shot upward from an arch running east and west, and that he had already made mention of black rays resembling dark smoke, as occurring in brilliant nocturnal northern lights.

References to the aurora australis are made by the naturalist John Reinhold Forster, in the article on “Aurora Borealis” of the “Encycl. Britannica.”

For Mountaine and Dodson, consult the Phil. Trans., Vol. XLVIII. p. 875; Vol. L. p. 329, also Hutton’s abridgments, Vol. XI. p. 149.

=A.D. 1738.=--Boze--Böse--(Georg Matthias) (1710–1761), Professor of Philosophy at Wittemburg, publishes his “Oratio inauguralis de electricitate,” which is followed, in 1746, by “Recherches sur la cause et sur la véritable théorie de l’électricité,” and, in 1747, by his completed “Tentamina electrica.”

To him is due the introduction in the electrical machine of the prime conductor, in the form of an iron tube or cylinder. The latter was at first supported by a man insulated upon cakes of resin and afterward suspended by silken strings. M. Boze discovered that capillary tubes discharging water by drops give a continuous run when electrified. He also conveyed electricity by a jet of water from one man to another, standing upon cakes of resin, at a distance of six paces, and likewise employed the jet for igniting alcohol as well as other liquids.

REFERENCES.--Alglave et Boulard, 1882, p. 22, also Priestley, 1775, upon “Miscellaneous Discoveries,” likewise “Nouv. Biog. Générale” (Hœfer), Vol. VI. p. 772; “La Grande Encycl.,” Vol. VII. p. 454; “Journal des Sçavans,” Vol. LXIII for 1718, p. 485; Phil. Trans. for 1745, Vol. XLIII. p. 419, and for 1749, Vol. XLVI. p. 189; also Hutton’s abridgments, Vol. IX. pp. 127, 681; and J. Martyn’s abridgments, Vol. X. part ii. pp. 277, 329.

=A.D. 1739.=--Desaguliers (Jean Theophile), chaplain to his Grace the Duke of Chandos, gives an account of his first experiments on the phenomena of electricity at pp. 186, 193, 196, 198, 200, 209, 634, 637, 638 and 661 of Vol. XLI of the Phil. Trans. for 1739. Some of these experiments were made on the 15th of April, 1738, at H.R.H. the Prince of Wales’ house at Cliefden.

He was the first to divide bodies into “electrics,” or non-conductors, and “non-electrics,” or conductors. He ranked pure air amongst his electrics (Tyndall, Lecture I) and stated that “cold air in frosty weather, when vapours rise least of all, is preferable for electrical purposes to warm air in summer, when the heat raises the vapours” (Phil. Trans., John Martyn abridgment, Vol. VIII. p. 437). It was Desaguliers who announced that he could render bars of iron magnetic, either by striking them sharply against the ground while in a vertical position or by striking them with a hammer when placed at right angles to the magnetic meridian.

His “Dissertation Concerning Electricity” London, 1742, which won for him the grand prize of the Bordeaux Academy, is said to be the second work on the subject published in the English language, the first having been Boyle’s “Mechanical Origin and Production of Electricity,” mentioned at A.D. 1675.

Desaguliers was the second to receive the Copley medal, it having been previously bestowed by the Royal Society only upon Stephen Grey, who obtained it in 1731 and 1732 for his “New Electrical Experiments.” The list of recipients of this distinguished honour, given by C. R. Weld at p. 385, Vol. I of the “History of the Royal Society,” shows that Desaguliers received three Copley medals; these were awarded him during the years 1734, 1736 and 1741, for his “Experiments in Natural Philosophy.” John Canton was given two of the medals, in 1751 and 1764, the only other electrician similarly favoured being Michael Faraday, who received them during the years 1832 and 1838, while Sir Humphry Davy is credited with only one, conferred upon him in 1805.

“Can Britain ... ... Permit the weeping muse to tell How poor neglected Desaguliers fell? How he, who taught two gracious kings to view, All Boyle ennobled, and all Bacon knew, Died in a cell, without a friend to save, Without a guinea, and without a grave?”

Cawthorn, “Vanity of Human Enjoyments,” V. 147–154.

In the year 1742, Desaguliers received the prize of the Académie Royale de Bordeaux for a treatise on the electricity of bodies, which latter was separately published at the time in a quarto volume of twenty-eight pages. The same Academy had previously conferred important prizes for dissertations, upon the nature of thunder and lightning by Louis Antoine Lozeran du Fech in 1726, upon the variations of the magnetic needle by Nicolas Sarrabat in 1727, and also subsequently decreed similar awards, to Laurent Béraud for an essay on magnets in 1748, to Denis Barberet for a treatise on atmospherical electricity in 1750, and to Samuel Theodor Quellmalz for a dissertation on medical electricity in 1753.

REFERENCES.--Phil. Trans., Vol. XL. p. 385; Vol. XLII. pp. 14, 140; also the following abridgments: Hutton, Vol. VIII. pp. 246–248, 340, 346, 350–358, 470–474, 479, 546, 584; John Martyn, Vol. VIII. part ii. pp. 419, 422–444, 740. Very interesting reading is afforded by M. Desaguliers through the observations he made on the magnets having more poles than two. These will be found recorded in Phil. Trans. for 1738, p. 383 and in Hutton’s abridgments, Vol. VIII. p. 246; Thomson, “Hist. Roy. Soc.,” 1812, pp. 433, 434; “Gen. Biog. Dict.,” Alex. Chalmers, London, 1811, Vol. XI. pp. 489–493.

=A.D. 1740.=--Celsius (Anders), who filled the chair of astronomy at Upsal, is first to point out the great utility of making simultaneous observations over a large extent of territory and at widely different points. He states (Svenska Vetenskaps Academiens Handlingar for 1740, p. 44) that a simultaneity in certain extraordinary perturbations, which had caused a horary influence on the course of the magnetic needle at Upsal and at London, afforded proof “that the cause of these disturbances is extended over considerable portions of the earth’s surface, and is not dependent upon accidental local actions.”

In the following year (1741), Olav Hiörter, who was Celsius’ assistant, discovered and measured the influence of polar light on magnetic variation. His observations were subsequently carried on in conjunction with Celsius, and were improved upon by Wargentin (A.D. 1750) and by Cassini (A.D. 1782–1791).

REFERENCES.--Walker, “Ter. and Cos. Magnetism,” p. 116; also Humboldt, “Cosmos,” re “Magnetic Disturbances,” and Vol. II. p. 438, of Weld’s “History of the Royal Society.”

=A.D. 1742.=--Gordon (Andreas), a Scotch Benedictine monk (1712–1757), Professor of Philosophy at Erfurt, abandons the use of glass globes (Newton, at A.D. 1675 and Hauksbee, at A.D. 1705), and is the first to employ a glass cylinder, the better to develop electricity. His cylinder, eight inches long and four inches wide, is made to turn by means of a bow with such rapidity that it attains 680 revolutions per minute.

Priestley says (“Discovery of Germans,” Part I. period vii.) that Gordon “increased the electric sparks to such a degree that they were felt from a man’s head to his foot, so that a person could hardly take them without falling down with giddiness; and small birds were killed by them. This he effected by conveying electricity, with iron wires, to the distance of 200 ells (about 250 yards) from the place of excitation.”

REFERENCES.--Dantzig Memoirs, Vol. II. pp. 358, 359, and Nollet, “Recherches,” etc., p. 172. See also Gordon’s “Phenomena Electricitatis Exposita,” Erford, 1744 and 1746; “Philosophia,” 1745; “Tentamen ... Electricitatis,” 1745; “Versuche ... einer Electricität.,” 1745–1746.

=A.D. 1743.=--Hausen (Christian Augustus), Professor of Mathematics at Leipzig, publishes his “Novi profectus in historia electricitatis,” and is the first to revive the use of the glass globe introduced by Newton (A.D. 1675) and employed with great effect by Hauksbee (A.D. 1705).

In Watson’s “Expériences et observations sur l’électricité,” is shown an electrical machine constructed by Hausen and differing but slightly from the one alluded to herein at A.D. 1705 as made for M. Wolfius. In this illustration a lady is pressing her hand against the glass globe, which is being rotated rapidly, thus developing upon its surface the vitreous electricity, while the resinous electricity passes through her body to the earth. The young man who is suspended and insulated by silken cords, represents the prime conductor introduced by Prof. Boze (A.D. 1738). The vitreous electricity passes from the surface of the glass globe, through his feet and entire body, and is communicated by his hand to the young girl, who stands upon a large section of resin, and is able to attract small parcels of gold leaf by means of the electric fluid. Another machine, taken from the same French work (originally published at Paris in 1748), is said to have been at that time much in use throughout Holland and principally at Amsterdam. The man rotates a glass globe, against which the operator presses his hand, and the electricity is conveyed through the metallic rod supported by silk-covered stands and held by a third party, who is igniting spirits in the manner indicated at the A.D. 1744 date.

REFERENCE.--Dantzig Memoirs, Vol. I. pp. 278, 279.

=A.D. 1743.=--Boerhaave--Boerhaaven--(Hermann), illustrious physician, mathematician and natural philosopher (1668–1738), who held the chairs of theoretical medicine, practical medicine, botany and chemistry at the University of Leyden, F.R.S. and member French Academy of Sciences, writes an Essay on the virtue of Magnetical Cures, of which there were subsequently many editions and translations in different languages.

One of his biographers calls him “the Galen, the Ibn Sina, the Fernel of his age.” Another remarks that he was, perhaps, the greatest physician of modern times: “A man who, when we contemplate his genius, his erudition, the singular variety of his talents, his unfeigned piety, his spotless character, and the impress which he left not only on contemporaneous practice, but on that of succeeding generations, stands forth as one of the brightest names on the page of medical history, and may be quoted as an example not only to physicians, but to mankind at large. No professor was ever attended, in public as well as at private lectures, by so great a number of students, from such distant and different parts, for so many years successively; none heard him without conceiving a veneration for his person, at the same time that they expressed their surprise at his prodigious attainments; and it may be justly affirmed, that none in so private a station ever attracted a more universal esteem.”

REFERENCES.--“Biographica Philosophica,” Benj. Martin, London, 1764, pp. 478–483; “Eloge de Boerhaave,” by Maty, Leyde, 1747, and by Fontenelle, 1763, T. VI; his life, written by Dr. Wm. Burton, London, 1736; Van Swinden, “Recueil,” etc., La Haye, 1784, Vol. II. p. 354, note; “La Grande Encyclopédie,” Tome VII. p. 42; “Biographie Générale,” Tome VI. pp. 352–357; “Biographie Universelle,” Vol. IV. pp. 529–555; Ninth “Encycl. Britannica,” Vol. III. p. 854; “Histoire Philosophique de la Médecine,” Etienne Tourtelle, Paris, An. XII. (1807), Vol. II. pp. 404–446; “Bibl. Britan.” (Authors), Rob. Watt, Edinburgh, 1824, Vol. I. p. 127; “The Edinburgh Encyclopædia,” 1830, Vol. III. pp. 628–630 or the 1813 ed., Vol. III. pp. 612–614; G. A. Pritzel, “Thesaurus Literaturæ Botanicæ,” Lipsiæ, 1851, p. 26.

=A.D. 1744.=--Ludolf--Leudolff--(Christian Friedrich), of Berlin, first exhibits, January 23, the ignition of inflammable substances by the electric spark. This he does in the presence of hundreds of spectators, on the occasion of the opening of the Royal Academy of Sciences by Frederick the Great of Prussia, when fire is set to sulphuric ether through a spark from the sword of one of the court cavaliers (see notes on Tyndall’s second lecture, 1876, p. 80).

It was likewise at this period Ludolf the younger demonstrated that the luminous barometer is made perfectly electrical by the motion of the quicksilver, first attracting and then repelling bits of paper, etc., suspended by the side of the tube, when it was enclosed in another tube out of which the air was extracted (Dantzig Memoirs, Vol. III. p. 495).

=A.D. 1744–1745.=--Waitz (Jacob Siegismund von), a German electrician, writes three essays in Dutch and one in French, and is given the prize of fifty ducats proposed by the Berlin Academy of Sciences for the best dissertation on the subject of electricity. In the following year he makes experiments, with Etienne François du Tour, to show the destruction of electricity by flame, and, later on, with Prof. Georg Erhard Hamberger, he proves conclusively that the motion of quicksilver in a glass vessel out of which the air is extracted has the power of moving light bodies. Jean Nicolas Sebastien Allamand subsequently found that it was immaterial whether the vessel had air in it or not.

REFERENCES.--Tyndall’s Notes on Lecture II, also Dantzig Memoirs, Vol. II. pp. 380, 426, and M. du Tour’s “Recherches sur les Différents Mouvements de la Matière Electrique,” Paris, 1760.

=A.D. 1745.=--Kratzenstein (Christian Gottlieb), Professor of Medicine at Halle, author of “Versuch einer Erklarung,” etc., and of “Theoria Electricitatis,” etc., is said to have first successfully employed electricity in the relief of sprains, malformations, etc. He observed that a man’s pulse, which had beat eighty in a second before he was electrified, immediately after beat eighty-eight, and was soon increased to ninety-six.

Kratzenstein is reported (Mary Somerville, “Physical Sciences,” Section XVII.) to have made instruments which articulated many letters, words and even sentences, and somewhat similar in construction to those alluded to at A.D. 1620 (De Bergerac), and A.D. 1641 (John Wilkins), some of which may truly be said to strongly suggest the modern phonograph.

Albertus Magnus constructed, after thirty years of experimentation, a curious machine which sent forth distinct vocal sounds, at which the very learned scholastic philosopher Saint Thomas Aquinas (“Angel of the Schools”) was so much terrified that he struck the contrivance with his stick and broke it. Bishop Wilkins alludes to this machine as well as to a brazen head devised by Friar Bacon, which could be made to utter certain words (“Journal des Savants” for 1899, and J. S. Brewer, “F. Rog. Bacon,” 1859, p. xci; also, “How Fryer Bacon made a Brasen Head to Speake,” at pp. 13–14 of the “Famous Historie of Fryer Bacon published at London for Francis Groue”).

Incidentally, it may be mentioned that Wolfgang von Kempelen, Aulic Counsellor to the Royal Chamber of the Domains of the Emperor of Germany, after witnessing some magnetic games shown to the Empress Maria Theresa at Vienna, constructed, during the year 1778, a speaking machine which “gave sounds as of a child three or four years of age, uttering distinct syllables and words” (Wm. Whewell, “Hist. of the Inductive Sciences,” Vol. II. chap. vi.; J. E. Montucla, “Hist. des Mathém,” Vol. III. p. 813).

La Nature, Paris, May 6, 1905, pp. 353–354, illustrates the speaking head of l’Abbé Mical presented by him to the French Academy of Sciences July 2, 1783, and alludes to those of Albertus Magnus, Wolfgang von Kempelen, C. G. Kratzenstein, etc.

Two more curious productions, in pretty much the same line as Bergerac’s, can, with equal propriety, be inserted here.

The first is taken from the April number, 1632, of the Courier Véritable, a little monthly publication in which novel fancies were frequently aired: “Captain Vosterloch has returned from his voyage to the southern lands, which he started on two years and a half ago, by order of the States-General. He tells us, among other things, that in passing through a strait below Magellan’s, he landed in a country where Nature has furnished men with a kind of sponge which holds sounds and articulations as our sponges hold liquids. So, when they wish to dispatch a message to a distance, they speak to one of the sponges, and then send it to their friends. They, receiving the sponges, take them up gently and press out the words that have been spoken into them, and learn by this admirable means all that their correspondents desire them to know.”

The second is the production of one Thomas Ward, theological poet, who was born in 1640 and died in 1704. In the second canto of one of his poems occur these words:

“As Walchius could words imprison In hollow canes so they, by reason, Judgment and great dexterity, Can bottle words as well as he; And can from place to place convey them, Till, when they please, the reed shall say them; Will suddenly the same discharge, And hail-shot syllables at large Will fly intelligibly out Into the ears of all about: So that the auditors may gain Their meaning from the breach of cane.”

REFERENCES.--Priestley, “History,” etc., 1775, p. 374, and Dantzig Memoirs, Vol. I. p. 294.

=A.D. 1745.=--Grummert (Gottfried Heinrich), of Biala, Poland, first observes the return of the electric light in vacuo. In order to ascertain whether an exhausted tube would give light when it was electrified, as well as when it was excited, he presented one eight inches long and a third of an inch wide, to the electrified conductor, and was surprised to find the light dart very vividly along the entire length of the tube. He likewise observed that some time after the tube had been presented to the conductor, and exposed to nothing but the air, it gave light again without being brought to an electrified body (see Dantzig Memoirs, Vol. I. p. 417).

=A.D. 1745.=--Dr. Miles (Rev. Henry), of Tooting, D.D. (1698–1763) reads, March 7, before the English Royal Society a paper indicating the possibility of kindling phosphorus by applying to it an excited electric without the approach of a conducting body. This gentleman’s tube happening to be in excellent order upon this occasion, he observed, and doubtless was the first to notice, pencils of luminous rays, which he called coruscations, darting from the tube without the aid of any conductor approaching it.

In a paper which Dr. Miles read before the same Society on the 25th of January, 1746, he gave an account of other equally interesting experiments, one of which was the kindling of ordinary lamp spirits with a piece of black sealing wax excited by dry flannel or white and brown paper.

REFERENCES.--“Dict. Nat. Biog.,” Sidney Lee, Vol. XXXVII. p. 378; Phil. Trans., Vol. XLIII. pp. 290, 441; Vol. XLIV. pp. 27, 53, 78, 158, and the following abridgments: Hutton, Vol. IX. pp. 107, 136, 191, 198, 207, 213, 232; John Martyn, Vol. X. part ii. pp. 272, 277, 317, 319, 322–323, 325.

=A.D. 1745.=--This period was to witness a discovery which, according to Professor Tyndall, “throws all former ones in the shade,” and which Dr. Priestley calls “the most surprising yet made in the whole business of electricity.” This was the accumulation of the electric power in a glass phial, called the Leyden jar after the name of the place where the discovery was made. It was first announced in a letter to Von Kleist, dean of the cathedral of Kamin--Cammin--in Pomerania, dated the 4th of November, 1745, and addressed to Dr. Lieberkühn, who communicated it to the Berlin Academy. The following is an extract: “When a nail or a piece of thick brass wire is put into a small apothecary’s phial and electrified, remarkable effects follow; but the phial must be very dry or warm; I commonly rub it over beforehand with a finger, on which I put some pounded chalk. If a little mercury, or a few drops of spirit of wine, be put into it, the experiment succeeds the better. As soon as this phial and nail are removed from the electrifying glass, or the prime conductor to which it has been exposed is taken away, it throws out a pencil of flame so long that, with this burning machine in my hand, I have taken above sixty steps in walking about my room; when it is electrified strongly I can take it into another room and there fire spirits of wine with it. If while it is electrifying I put my finger, or a piece of gold which I hold in my hand, to the nail, I receive a shock which stuns my arms and shoulders.”

It is said that Cunæus, rich burgess of Leyden, accidentally made the same discovery in January 1746. It appears that Pieter Van Musschenbroek, the celebrated professor, while experimenting with his colleagues, Cunæus and Allamand, observed that excited bodies soon lost their electricity in the open air, attributable to the vapours and effluvia carried in the atmosphere, and he conceived the idea that the electricity might be retained by surrounding the excited bodies with others that did not conduct electricity. For this purpose he chose water, the most readily procured non-electric, and placed some in a glass bottle. No important results were obtained until Cunæus, who was holding the bottle, attempted to withdraw the wire which connected with the conductor of a powerful electric machine. He at once received a severe shock in his arms and breast, as did also the others upon renewing the experiment. In giving an account of it to the great scientist, René de Réaumur, Musschenbroek remarked: “For the whole kingdom of France, I would not take a second shock.” Allamand states that when he himself took the shock “he lost the use of his breath for some minutes, and then felt so intense a pain along his right arm that he feared permanent injury from it.”

In his “Cours Elémentaire de Physique,” Musschenbroek describes one of the peculiar electrical machines then being constructed by the well-known London instrument maker, George Adams, and a cut of it can be seen at p. 353, Vol. I. of the translation made by Sigaud de la Fond at Paris during 1769. Another of Adams’ machines is described and illustrated at p. 126 of the French translation of Cavallo’s “Complete Treatise,” published at Paris in 1785.

The invention of the Leyden jar is claimed with equal pertinacity for Kleist, Musschenbroek and Cunæus. While it is necessarily conceded that Von Kleist first published his discovery, it cannot be denied that his explanation of it is so obscure as, for the time, to have been of no practical use to others. It is stated by Priestley: “Notwithstanding Mr. Kleist immediately communicated an account of this famous experiment (which indeed it is evident he has but imperfectly described) to Mr. Winckler, at Leipzig, Mr. Swiettiki, of Denmark, Mr. Kruger, of Halle, and to the professors of the Academy of Lignitz, as well as to Dr. Lieberkühn, of Berlin, above mentioned, they all returned him word that the experiment did not succeed with them. Mr. Gralath, of Dantzig, was the first with whom it answered; but this was not till after several fruitless trials, and after receiving further instructions from the inventor. The Abbé Nollet had information of this discovery, and, in consequence of it says, in a letter to Mr. Samuel Wolfe, of the Society of Dantzig, dated March 9, 1746, that the experiment at Leyden was upon principles similar to that made with a phial half full of water and a nail dipped in it; and that this discovery would have been called the Dantzig experiment if it had not happened to have got the name of that of Leyden.”

In the thirty-eighth volume of the Philosophical Transactions, No. 432, p. 297, is given an abstract of a letter (dated Utrecht, January 15, 1733, O. S.), from Petrus Van Musschenbroek, M.D., F.R.S., to Dr. J. T. Desaguliers, concerning experiments made on the Indian Magnetic Sand, chiefly gathered along the seashore in Persia. After detailing his many observations, Van Musschenbroek asks: “And, now, what can this sand be? Is it an imperfect magnet, or Subtile Powder of it, which, when it is grown up into a greater lump, makes the vulgar Loadstones? So I conjectured at first; but when I found by experience that common Loadstones, exposed to the fire, according to some of the methods above-mention’d, did rather lose of their force than gain, I alter’d my opinion; and now confess that I have not yet penetrated into the knowledge of the nature of this matter.”

REFERENCES.--Dalibard, “Histoire Abrégée,” p. 33; Dantzig Memoirs, Vol. I. pp. 407, 409, 411; Johann Gottlob Kruger, “Dissert. de Elect.,” Helmstadt, 1756 (Poggendorff, I. p. 1323); Priestley, 1777, “The Hist. and Pres. State of Electricity,” pp. 82–84; Opuscoli Scelti, 4to, xviii, 55; Pierre Massuet, “Essais,” Leide, 1751; Musschenbroek’s “Epitome elementorum,” etc., 1726, “Tentamina Experimentorum Naturalium,” 1731, and his “Disertatio Physica experimentalis de Magnete,” as well as his “Elementa Physicæ,” 1734, and the “Introductio ad Philosophiam Naturalem,” 1762, the last-named two works being greatly amplified editions of the “Epitome.” For Musschenbroek--Musschenbrock--consult also Phil. Trans., Vol. XXXII. p. 370; Vol. XXXVII. pp. 357, 408, also the following abridgments: Baddam, 1745, Vol. VIII. p. 42; Reid and Gray, Vol. VI. p. 161 (Musschenbroek to Desaguliers); Hutton, Vol. VII. pp. 105, 647 (magnetic sand); Eames and Martyn, Vol. VI. part ii. p. 255; John Martyn, Vol. VIII. p. 737 (magnetic sand). For this magnetic sand, consult also Mr. Butterfield’s article in Phil. Trans. for 1698, p. 336 and in the abridgments of Hutton, Vol. IV. p. 310.

=A.D. 1745.=--Watson (William), M.D., F.R.S., an eminent English scientist, bears “the most distinguished name in this period of the history of electricity.” His first letters, treating of this science, are addressed to the Royal Society between March 28 and October 24, 1745, and, on the 6th of February and the 30th of October, 1746, he communicated other similar papers to the same Society, all which, like his subsequent treatises, are to be found in the Philosophical Transactions.

Dr. Watson, like most scientists at the time, made numerous experiments with the Leyden jar, and he was the first to observe the flash of light attending its discharge. He says: “When the phial is well electrified, and you apply your hand thereto, you see the fire flash from the outside of the glass wherever you touch it, and it crackles in your hand.” It is to him that we owe the double coating of the jar, as well as the plus and minus of electricity.

He also shows conclusively that glass globes and tubes do not possess in themselves the electrical power, but only serve “as the first movers or determiners of that power,” and he also proves that the electric fluid takes the shortest course, passing through the substance of the best medium of connection and not along its surface. This, he demonstrated by discharging a phial through a wire covered with a mixture of wax and resin.

In order to ascertain the velocity of the electric fluid from the Leyden phial and the distance at which it could be transmitted (John Wood, at A.D. 1726), Watson directed a series of experiments upon a very grand scale, with the assistance of Martin Folkes, President of the Royal Society, Lord Charles Cavendish, Dr. Bevis, Mr. Graham, Dr. Birch, Peter Daval and Messrs. Trembley, Ellicott, Robins and Short. On the 14th and 18th of July, 1747, they experimented upon a wire carrying the electricity from the Thames bank at Lambeth to the opposite bank at Westminster, across Westminster Bridge, and, on the 24th of July, at the New River, Stoke Newington, they sent a shock through 800 feet of water and 2000 feet of land, as well as through 2800 feet of land and 8000 feet of water. Other experiments followed on the 28th of July and the 5th of August, as well as on the 14th of August of the same year, proving the instantaneous transmission of the fluid; while a year later, August 5, 1748, additional observations were made, through 12,276 feet of wire, at Shooter’s Hill, showing again that the time occupied in the passage of the electricity was “altogether inappreciable.” Regarding these experiments, Prof. Musschenbroek wrote to Dr. Watson, “Magnificentissimis tuis experimentis superasti conatus omnium.”

Watson’s experiments were repeated, notably by Franklin, across the Schuylkill at Philadelphia, in 1748; by Deluc, across the Lake of Geneva, in 1749; and by Winckler, at Leipzig, in 1750. It is said that Lemonnier (A.D. 1746) produced shocks at Paris through 12,789 feet of wire and that Bétancourt (A.D. 1795) discharged electric jars through a distance of twenty-six miles.

To Dr. Watson is also due the first demonstration of the passage of electricity through a vacuum. Noad tells us that he caused the spark from his conductor to pass in the form of coruscations of a bright silver hue through an exhausted tube three feet in length, and he discharged a jar through a vacuum interval of ten inches in the form of “a mass of very bright embodied fire.” These demonstrations were repeated and varied by Canton, Smeaton and Wilson.

His experiments in firing gunpowder, hydrogen, etc., by the electric spark, are detailed at p. 78 of Priestley’s “History,” etc., London, 1775.

Watson was rewarded with the Copley medal for his researches in electricity, which brought him also honorary degrees from two German universities. He was knighted in 1786, one year before his death.

REFERENCES.--“Watson’s Experiments and Observations on Electricity,” 1745, also his “Account of the Experiments made by some gentlemen of the Royal Society,” etc., 1748; Phil. Trans., Vol. XLIII. p. 481; Vol. XLIV. pp. 41, 388, 695, 704; Vol. XLV. pp. 49–120, 491–496; Vol. XLVI. p. 348; Vol. XLVII. pp. 202, 236, 362, 567; Vol. XLVIII. p. 765; Vol. LI. p. 394 (lyncurium of the ancients); Vol. LIII. p. 10; also the following abridgments: Hutton, Vol. IX. pp. 151, 195, 308, 368, 408, 410, 440, 553; Vol. X. pp. 12, 189, 197, 227, 233, 242, 303, 372–379, 525; Vol. XI. p. 419 (lyncurium of the ancients), 580, 660, 679; Vol. XII. p. 127; John Martyn, Vol. X. part ii. pp. 279–280, 290, 294, 329, 339, 347, 368, 407, 410. See likewise, Scientific American Supplement of Oct. 5, 1889, No. 718, pp. 11, 471, for an interesting engraving of Dr. Watson’s experiment made through the water of the Thames, as well as for a detailed account of Lemonnier’s experiment above referred to. For Mr. A. Trembley, consult Phil. Trans., Vol. XLIV. p. 58, and John Martyn’s abridgments, Vol. X. part ii. p. 321.

=A.D. 1746.=--Lemonnier (Pierre Claude Charles), a distinguished savant, who was member of the French Academy as adjunct geometrician before he had attained his twenty-first year and became foreign member of the English Royal Society three years later, was the first scientist who drew electricity from the narrow domain of the laboratory.

He confirmed the result previously obtained by Grey (A.D. 1720) that electric attraction is not proportioned to the mass or quantity of matter in bodies, but only to the extent of their surface, length having greater effect than breadth (Phil. Trans., Vol. XLIV for 1746, p. 290; Snow Harris, “Treatise on Frict. Elect.,” London, 1867, p. 239, and “Hist. de l’Acad.,” 1746). He found that an anvil weighing two hundred pounds gives but an inconsiderable spark, while the spark from a tin speaking-trumpet eight or nine feet long, but weighing only ten pounds, is almost equal to the shock of the Leyden phial. A solid ball of lead, four inches in diameter, gives a spark of the same force as that obtained from a thin piece of lead of like superficies bent in the form of a hoop. He took a thin and long piece of lead, and noticed that when it was electrified in its whole length it gave a very strong spark, but a very small one when it was rolled into a lump (Ac. Par., 1746, M. p. 369). It had likewise been shown by Le Roi and D’Arcy that a hollow sphere accepted the same charge when empty as when filled with mercury, which latter increased its weight sixtyfold; all proving the influence of surface as distinguished from that of mass (Tyndall, Notes on Lecture IV).

Lemonnier discovered that electricity is ever present in the atmosphere, that it daily increases in quantity from sunrise till about three or four o’clock in the afternoon, diminishing till the fall of dew, when it once more increases for a while, and finally diminishes again before midnight, when it becomes insensible. He observed a continual diminution of electricity as the rain began to fall, and he says: “When the wire was surrounded with drops of rain, it was observed that only some of them were electrical, which was remarkable by the conic figure they had; whilst the others remained round as before. It was also perceived that the electrical and non-electrical drops succeeded almost alternately; this made us call to mind a very singular phenomenon which happened some years before, to five peasants who were passing through a cornfield, near Frankfort upon the Oder, during a thunderstorm; when the lightning killed the first the third and the fifth of them, without injuring the second or the fourth” (Phil. Trans., Vol. XLVII. p. 550).

REFERENCES.--Le Monnier, “Lois du Magnétisme,” Paris, 1776–1778; Phil. Trans., Vol. XLIV. p. 247; Vol. XLVIII. part i. p. 203; “Journal des Sçavans,” Vol. CXII for 1737, p. 73; also Hutton’s abridgments, Vol. IX. pp. 275, 308, 368, 591 (biogr.); John Martyn’s abridgments, Vol. X. part ii. pp. 329–348; “Philosophical Magazine,” Vol. VI. for 1800, p. 181, “Some Account of the Late P. C. Le Monnier,” 1715–1799; “Mémoires de l’Institut Nat. des Sc. et des Arts,” Hist. An. IX. p. 101; Mémoires de l’Acad. Royale des Sciences, 1746, pp. 14–24, 447, 671–696; 1752, Tome I. pp. 9–17, Tome II. 233–243, 346–362; 1770, p. 459; Bertholon, “Elec. du Corps Humain,” 1786, Vol. I. pp. 10–14; Harris, “Frict. Elec.,” p. 239; Sc. American Supplement, for Oct. 5, 1889, No. 718, pp. 11, 471. See also reports of the experiments of G. B. Beccaria, G. F. Gardini (“De inflexu,” etc., ss. 50, 51), Andrew Crosse and others at “Bibl. Britan. Sc. et Arts,” 1814, Vol. LVI. p. 524.

=A.D. 1746.=--Bevis (John), English astronomer and Secretary of the Royal Society, first suggested to Dr. Watson the external coating of the Leyden jar with tinfoil or sheet-lead, and was likewise the first to observe that the force of the charge increases as larger jars are employed, but not in proportion to the quantity of water they contain. As water only played the part of a conductor, he rightly thought that metal would do equally well, and he therefore filled three jars with leaden shot instead of with water. When the metallic connection was made it was found that the discharge from three jars was greater than that from two and the discharge from two much greater than that from one. This showed that the seat of the electric force is the surface of the metal and the glass, and proves that the force of the charge is in proportion to the quantity of coated surface.

Thus to Dr. Bevis belongs the credit of having constructed the first electric battery, although the honour has been claimed by the friends of Daniel Gralath (A.D. 1747).

REFERENCES.--Phil. Trans., abridged, Vol. X. pp. 374, 377; Wilson, “Treatise,” London, 1752, Prop. XVII. p. 107.

=A.D. 1746.=--Le Cat (Claude Nicolas), a physician of Rouen, observed, when suspending several pieces of leaf gold at his conductor, that they hung at different distances according to their sizes, the smallest pieces placing themselves nearest the conductor and the largest farthest from it.

Le Cat (1700–1768) became celebrated for his surgical operations and succeeded in carrying off all the first prizes offered by the Royal Academy of Surgeons between the years 1734 and 1738 inclusively. Consult his different works named at p. 292 of Ronalds’ “Catalogue”; “Histoire de l’Electricité,” pp. 84 and 85; “Biographie Générale,” Vol. XXX. pp. 179–182.

=A.D. 1746.=--Maimbray (M.), of Edinburgh, electrified two myrtle trees, during the entire month of October 1746, and found that they put forth small branches and blossoms sooner than other shrubs of the same kind which had not been electrified. This result was confirmed by the Abbé Nollet, who filled two pots with vegetating seeds and found that the pot which he had constantly electrified for fifteen consecutive days put forth earlier sprouts as well as more numerous and longer shoots than did the other.

Like experiments were at the same time carried on with equal success by M. Jallabert and M. Boze, as well as by the Abbé Menon, Principal of the College of Bueil at Angers, France. The last named also found that electricity increases the insensible perspiration of animals. He chose cats, pigeons and chaffinches, and observed after they were electrified, that one cat was sixty-five or seventy grains lighter than the other, the pigeon from thirty-five to thirty-eight grains, and the chaffinch had lost six or seven grains. He also electrified a young person between the ages of twenty and thirty, for five hours and found a loss in weight of several ounces.

With reference to the effect of electricity on different varieties of growing plants, a paper in Boston not long ago published the following:

“In the last few years some very interesting experiments in gardening by electricity have been made by Prof. Selim Lemström, of the University of Helsingfors. These have been carried out both upon the potted plants in the hot-house and upon plants in the open field, the insulated wires in the latter case being stretched upon poles over the plot of ground, and provided with a point for each square metre of area. The current has been supplied by Holtz machines run from eight to eighteen hours daily, the positive pole being connected with the network of wires and the negative with a zinc plate buried in the ground. The electric influence was scarcely perceptible in the growing plants, but was very marked in the yield of many species, especially of barley and wheat, of which the crop was increased by half in some cases. In the hot-house the maturity of strawberries was greatly advanced. The results have shown that plants may be divided into two groups: one, the development of which is favoured by electricity, comprising wheat, rye, barley, oats, red and white beets, parsnips, potatoes, celeriac, beans, raspberries, strawberries and leeks; and the other, whose development is more or less interfered with by electricity, including peas, carrots, kohlrabi, rutabagas, turnips, white cabbages and tobacco. The more fertile the soil, and consequently the more vigorous the vegetation, the greater has been the excess of the crop under electric influence. Prof. Lemström’s experiments up to 1887 were carried on in Finland, but he has since repeated his work in France, and demonstrated that the electric influence is the same in any climate, though likely to be injurious under a scorching sun.”

REFERENCES.--Nollet, “Recherches sur l’Electricité,” pp. 366, 382; Phil. Trans., abridged, Vol. X. p. 384; _Electrical Review_, London, June 5, 1891, p. 707.

=A.D. 1746.=--Knight (Gowan or Gowin), F.R.S., an English physician, is the first to make very powerful steel magnets. The method, which he long succeeded in keeping secret, was described after his death, in the Phil. Trans. for 1746–1747, Vol. XLIV. It consists of placing two magnets in the same straight line, with their opposite poles close to or very near each other, and in laying under them the bar to be magnetized after having it tempered at a cherry-red heat. The magnets are then drawn apart in opposite directions along the bar, so that the south pole of one magnet passes over the north polar half, and the north pole of the other magnet passes over the south polar half of the bar.

This was how Dr. Knight made the bars of the two great magnets of the Royal Society. Each magnet contained two hundred and forty bars, fifteen inches long, one inch wide and half an inch thick. Dr. Robison described, in 1800, the effect of pressing together the dissimilar poles of the two magnets, and, thirty years later, Prof. Faraday, upon placing a soft iron cylinder, one foot long and three-quarters of an inch in diameter, across the dissimilar poles, found that he required a force of one hundred pounds to break down the attractive power.

Previously to Dr. Knight’s discovery, the method of making artificial magnets most in use was by simply rubbing the bar to be magnetized upon one of the poles of a natural magnet in a plane at right angles to the line joining its two poles.

Another secret of Dr. Knight was also, after his death, made known to the Royal Society by its secretary, Mr. Benjamin Wilson. It was the mode of making artificial paste magnets. He collected a large quantity of iron filings, which he cleansed and made into a fine powder under water and afterward dried and mixed, preferably with linseed oil. This was baked into cakes, which were magnetized by placing them between the ends of his magazine of artificial magnets.

To Dr. Knight was given the first English patent in the Class of Electricity and Magnetism. It bears date June 10, 1766, No. 850, and is for the construction of “Compasses so as to prevent them being affected by the motion of the ship,” etc.

REFERENCES.--Phil. Trans., Vol. XLIII. pp. 161, 361; Vol. XLIV. p. 656; Vol. XLIX. p. 51; Vol. LXVI. p. 591; C. R. Weld, “Hist. of Roy. Soc.,” Vol. I. p. 511; Noad, “Manual,” 1859, p. 593; Sturgeon, “Sc. Researches,” Bury, 1850, p. 249; also the abridgments by Hutton, Vol. IX. pp. 71, 74, 122, 390 (Folkes), 653; Vol. X. pp. 64, 67; Vol. XIV. pp. 117, 480; and by John Martyn, Vol. X. part ii. pp. 678–698.

=A.D. 1746.=--Gravesande (Wilhelm Jacob), celebrated Dutch mathematician and natural philosopher (1688–1742), whose family name was Storen Van ’Sgravesande, is the author of “Eléments de physique démontrés mathématiquement ... ou introduction à la philosophie Newtonienne,” which was translated from the Latin and published at Leyden in 1746.

At p. 87 of the second volume of the last-named work he gives a description of an electrical machine constructed on the plan of that of Hauksbee. It consisted merely of a crystal globe, which was mounted upon a copper stand, and against which was pressed the hand of the operator while it was made to revolve rapidly by means of a large wheel.

Gravesande taught publicly on the Continent the philosophy of Newton, and, by so doing, was one of the first to bring about a revolution in the domain of physical sciences generally. His original “Physices Elementa Mathematica,” as well as his “Philosophiæ Newtonianæ,” etc., and “Introductio ad Philosophiam,” etc., were respectively published at Leyden in 1720, 1723 and 1736.

REFERENCE.--Houzeau et Lancaster, “Bibl. Générale,” Vol. II. p. 252.

=A.D. 1746.=--Nollet (Jean Antoine), a distinguished French philosopher (1700–1770), to whom was given the title of Abbé while holding deacon’s orders, is the first in France to make experiments with the Leyden jar.

While in Paris he applied himself to electrical studies in company with Charles Dufay (already noticed at A.D. 1733), and made such ingenious experiments that René de Réaumur allowed him the free use of his extensive apparatus and laboratory. During the month of April 1746, he transmitted, in the presence of the French King, an electrical shock from a small phial through a chain of one hundred and eighty of the Royal Guards, and at the Carthusian Convent, not long afterward, he sent a shock through a line of monks stretched a distance of over a mile, causing them all to experience instantaneously the same sensation.

Nollet’s work, “Essai sur l’électricité des corps,” was originally published at Paris in 1746. He was the first to observe that pointed bodies electrified give out streams of light (the smallest points displaying “brushes of electric light”), but that they do not exhibit as powerful indications of electricity as are shown by blunt bodies. He also found that glass and other non-conductors are more strongly excited in air than in vacuo; that the electric spark is more diffuse and unbroken in vacuo; and that an excited tube loses none of its electricity by being placed in the focus of a concave mirror when the sunlight is therein concentrated.

His experiments upon the evaporation of fluids by electricity, as well as upon the electrification of capillary tubes full of water (observed also by Boze), and upon the electrification of plants and animals, are detailed in his “Recherches,” etc., pp. 327, 351, 354–356, while his observations upon the electrical powers of different kinds of glass are given in the sixth volume of the “Leçons de Physique Expérimentale,” issued in 1764.

As has been truly said, it is no easy matter to form an adequate idea of Nollet’s theory of electricity, which was opposed at the time by almost all the eminent electrical philosophers of Europe. He asserted that when an electric is excited, electricity flows to it from all quarters, and when it is thus affluent, it drives light bodies before it. Hence the reason why excited bodies attract. When the electricity is effluent the light bodies are of course driven from the electric, which in that condition appears to repel. He therefore believed every electric to be possessed of two different kinds of pores, one for the emission of the electric matter, and the other for its reception.

Nollet is the first one who published the close relationship existing between lightning and the electric spark. This he did during the year 1748, in the fourth volume of his “Leçons,” already alluded to and from which the following is extracted: “If any one should undertake to prove, as a clear consequence of the phenomenon, that thunder is in the hands of nature what electricity is in ours--that those wonders which we dispose at our pleasure are only imitations on a small scale of those grand effects which terrify us, and that both depend on the same mechanical agents ... I confess that this idea, well supported, would please me much.... The universality of the electric matter, the readiness of its actions, its instrumentality and its activity in giving fire to other bodies, its property of striking bodies, externally and internally, even to their smallest parts ... begin to make me believe that one might, by taking electricity for the model, form to one’s self, in regard to thunder and lightning, more perfect and more probable ideas than hitherto proposed.”

For a memoir treating of the cause of thunder and lightning, written by the Rev. Father de Lozeran de Fech, of Perpignan, the Bordeaux Academy of Sciences had in 1726 awarded him its annual prize; and the same institution conferred a similar award, in August 1750, upon M. Bergeret, a physician of Dijon, whose memoir admitted the close analogy between lightning and electricity.

REFERENCES.--Ronalds’ “Catalogue,” pp. 369–371; Jean Morin, “Réplique,” Paris, 1749; A. H. Paulian, “Conjectures,” 1868; “Abrégé des transactions philosophiques,” Vol. X. p. 336; “Mémoires de mathématique,” etc., pour 1746, p. 22; “Journal des Sçavans,” Vol. CXVII. for 1739, pp. 111–115, and Vol. CXLII for 1747, pp. 248–265; “Medical Electricity,” by Dr. H. Lewis Jones, Philad., 1904, p. 2; “Mémoires de l’Acad. Royale des Sciences” pour 1745, p. 107; 1746, p. 1; 1747, pp. 24, 102, 149, 207; 1748, p. 164; 1749, p. 444; 1753, pp. 429, 475; 1755, p. 293; 1761, p. 244; 1762, pp. 137, 270; 1764, pp. 408–409; 1766, p. 323; “Leçons,” eighth edition, Vol. IV. p. 315; Phil. Trans., Vol. XLV. p. 187; Vol. XLVI. p. 368; Vol. XLVII. p. 553; also the following abridgments: Hutton, Vol. X. pp. 20, 295, 372–379, 446 (Dr. Birch); Vol. XI. p. 580; John Martyn, Vol. X. part ii. pp. 277–333, 382 (Folkes), 414. See the experiments of Etienne François du Tour, “Sur la manière dont la flamme agit sur les corps electriques,” in a letter addressed by him to Nollet in 1745, and in “Mém. de Mathém. et Phys.,” Vol. II. p. 246, Paris, 1755; also Zantedeschi and Faraday on the “Magnetic Condition of Flame” (Faraday’s “Exper. Res.,” Vol. III. pp. 490–493).

=A.D. 1746.=--Wilson (Benjamin) (1721–1788), Secretary to the Royal Society, writes his “Essay toward an explication of the phenomena of Electricity deduced from the ether of Sir Isaac Newton.” In the chapter of Priestley’s “History” treating of the Theories of Electricity, he says: “With some, and particularly Mr. Wilson, the chief agent in all electrical operations is Sir Isaac Newton’s ether, which is more or less dense in all bodies in proportion to the smallness of their pores, except that it is much denser in sulphureous and unctuous bodies. To this ether are ascribed the principal phenomena of attraction and repulsion, whereas the light, the smell, and other sensible qualities of the electric fluid are referred to the grosser particles of bodies, driven from them by the forcible action of this ether. Many phenomena in electricity are also attempted to be explained by means of a subtile medium, at the surface of all bodies, which is the cause of the refraction and reflection of the rays of light, and also resist the entrance and exit of this ether. This medium, he says, extends to a small distance from the body, and is of the same nature with what is called the electric fluid.[50] On the surface of conductors this medium is rare and easily admits the passage of the electric fluid, whereas on the surface of electrics it is dense and resists it. This medium is rarefied by heat, which converts non-conductors into conductors.”

At pp. 71 and 88, 1746 edition, and at p. 88, Prop. XI. of the 1752 edition of this same “Essay,” Wilson says that during the year 1746 he discovered a method of giving the shock of the Leyden jar to any particular part of the body without affecting any other portion; that he increased the shock from the jar by plunging it into water, thereby giving it a coating of water on the outside as high as it was filled on the inside; and that the accumulation of electricity in the Leyden jar is always in proportion to the thinness of the glass, the surface of the glass and that of the non-electrics in contact with the inside and outside thereof.

It was in this same year, 1746, that Wilson first observed the lateral shock or return stroke, which was not, however, explained until Lord Mahon, third Earl of Stanhope, published his “Principles of Electricity,” in 1779.

On the 13th of November, 1760, a paper of Mr. Wilson’s was read before the Royal Society, in which he detailed several of his ingenious experiments on the plus and minus of electricity, and showed that these can be produced at pleasure by carefully attending to the form of bodies, their sudden or gradual removal and the degrees of electrifying. He had previously noticed that when two electrics are rubbed together, the body whose substance is hardest and electric power strongest is always electrified positively and the other negatively. Rubbing the tourmaline and amber together he produced a plus electricity on both sides of the stone and a minus on the amber; but, rubbing the diamond and the tourmaline, both sides of the tourmaline were electrified minus and the diamond plus. When insulated silver and glass were rubbed, the silver became minus and the glass plus.

He further observed that when directing a stream of air against a tourmaline, a pane of glass or a piece of amber, these were electrified plus on both sides. Prof. Faraday subsequently showed that no electrical effect is produced in these cases unless the air is either damp or holds dry powders in suspension, the electricity being produced by the friction of particles of water in the one case and by the particles of powder in the other. Sir David Brewster, who thus mentions the latter fact, likewise singles out two more of Mr. Wilson’s observations, viz. that when a stick of sealing-wax is broken across or when a dry, warm piece of wood is rent asunder, one of the separated surfaces becomes vitreously and the other resinously electrified.

REFERENCES.--De La Rive, “Electricity,” Vol. I. p. 203; Wilson, “Treatise on Electricity”; Wilson and Hoadley, “Observations on a Series of Electrical Experiments”; Phil. Trans., Vol. XLVIII. p. 347; Vol. XLIX. p. 682; Vol. LI. part i. pp. 83, 308, 331, part ii. p. 896; Vol. LIII. pp. 436, etc.; Vol. LXVIII. p. 999; Vol. LXIX. p. 51; also Hutton’s abridgments; Vol. X. p. 420; Vol. XI. pp. 15, 396, 504; Vol. XII. pp. 44, 147; Vol. XIII. p. 374; Vol. XIV. pp. 334, 337, 458, 480; “The Electrical Researches of the Hon. Henry Cavendish,” Cambridge, 1879, No. 125; L. E. Kaemtz, “Lehrbuch der Meteor,” Halle, 1832, Vol. II. p. 395.

=A.D. 1746.=--Ellicott (John), of Chester, suggests a method of estimating the exact force of the electric charge contained in the Leyden jar by its power to raise a weight in one scale of a balance while the other scale is held over and attracted by the electrified body. This was the principle upon which Mr. Gralath constructed the electrometer shown in Dantzig Memoirs, Vol. I. p. 525.

With reference to the experiments of Boze (A.D. 1738) and of Nollet (A.D. 1746) made with capillary tubes, he says that the siphon, though electrified, will only deliver the water by drops if the basin containing the water is also electrified. He explains Nollet’s observation, that the electric matter issues more sensibly from the point at the extremity of the conductor, by saying that the effluvia, in rushing from the globe along the conductor, as they approach the point are brought nearer together, and therefore are denser there, and if the light be owing to the density and velocity of the effluvia it will be visible at the point and nowhere else. Ellicott’s theory of electricity is founded upon the following data: (1) electrical phenomena are produced by effluvia; (2) these effluvia repel each other; (3) they are attracted by all other matter. If the word fluid is substituted for effluvia, these data absolutely agree with those adopted by Æpinus and Cavendish, forming the basis of the only satisfactory theory of electricity hitherto proposed.

REFERENCES.--Boulanger, “Traité de la Cause et des phénomènes de l’électricité,” Paris, 1750, p. 324; Phil. Trans. for 1746, Vol. XLIV. p. 96, and for 1748, Vol. XLV. pp. 195–224, 313; also the abridgments of John Martyn, Vol. X. part ii. pp. 324, 386, 389, 394; Hutton, Vol. IX. p. 475.

=A.D. 1747.=--Pivati (Johannes Francisco), a Venetian physician, relates in his “Lettere della elettricita medica,” that if odorous substances are confined in glass vessels and the latter excited, the odours and other medical virtues will transpire through the glass, infect the atmosphere of a conductor, and communicate the virtue they may possess to all persons in contact therewith; also, that those substances held in the hands of persons electrified will communicate their virtue to them so that medicines can thus be made to operate without being taken in the usual manner.

This appears to have been likewise asserted especially by M. Veratti, of Bologna, and by M. Bianchi, of Turin; also by Prof. Winckler, of Leipzig, who satisfied himself of the power of electricity on sulphur, cinnamon, and on balsam of Peru even at a distance.

By the above-named means of applying the electric fluid Pivati is reported to have effected cures of ordinary pains and aches, and to have even relieved of gout the old Bishop Donadoni, of Sebenico, who had long been a sufferer, and who was at the time seventy-five years of age. This pretended transudation and its medical effects could not, however, be verified, even with the directions asked of and given by Prof. Winckler, when very careful and exhaustive experiments were made, on the 12th of June, 1751, at the house of Dr. Watson, in presence of the president and other officers as well as friends of the Royal Society. Nor could Dr. Bianchini, Professor of Medicine at Venice, succeed any better. At a later date, Franklin asserted that it was impossible to combine the virtues of medicines with the electric fluid.

REFERENCES.--Franklin’s Letters, p. 82; Phil. Trans. for 1748, Vol. XLV. pp. 262, 270; for 1750, Vol. XLVI. pp. 348, 368; for 1751, Vol. XLVII. p. 231; for 1753, Vol. XLVIII. pp. 399, 406, and Vol. X. abridged, pp. 400–403.

=A.D. 1747.=--Louis (Antoine), eminent French surgeon (1723–1792), publishes “Observations sur l’électricité,” of which the first issue appeared in 1747 and wherein he indicates the employment of electricity in medical practice. This he did again in his “Recueils,” upon a more pretentious scale, six years later, 1753.

REFERENCES.--N. F. J. Eloy, “Dict. de la Médecine,” Mons, 1778, Vol. III. p. 206; “Gen. Biog. Dict.” of Alex. Chalmers, 1815, Vol. XX. p. 419; Hœfer, “Nouv. Biog. Gén.,” Vol. XXXI. p. 1033; Quérard, “La France Littéraire”; “Biog. Univ.,” de Michaud, Vol. XXV. pp. 319–325.

=A.D. 1747.=--Gralath (Daniel) publishes in the Dantzig Memoirs his “Geschichte der Electricität.”

He is the first to construct a Leyden phial with a long, narrow neck, through which is passed an iron wire bearing a tin knob in place of the iron nail theretofore used; and, with several of these phials joined together in the form of a battery, he had, during the previous year, transmitted a shock through a chain of twenty persons. His observations are recorded in the above-named Memoirs at pp. 175–304 and 506–534, Vol. I.; pp. 355–460, Vol. II.; pp. 492–556, Vol. III. Gralath’s “Electrische Bibliothek” is in Vols. II. and III.

=A.D. 1747.=--The Swedish mathematician and philosopher, Samuel Klingenstierna, and his pupil, M. Stroemer, were the first who properly electrified by the rubber, and their experiments were published in the Acts of the Royal Academy of Sciences at Stockholm for the year 1747 (see Priestley’s “History of Electricity,” Part I. period viii. s. 3, wherein he alludes to Wilcke’s “Herrn Franklin’s briefe,” etc., p. 112).

=A.D. 1748.=--Morin (Jean), French physicist, publishes at Chartres “Nouvelle dissertation sur l’électricité des corps,” etc., in which he details many of his experiments, and endeavours to give a correct explanation of all the extraordinary electrical phenomena hitherto observed. He is also the author of a “Reply to Mr. Nollet upon Electricity,” published in 1749 at Chartres and at Paris, as well as of a treatise upon Universal Mechanism, which latter, according to the Journal des Savants, contained more information upon Nature generally, and expressed in fewer words, than was embraced in any previous work.

REFERENCES.--“Dict. Univ.,” Vol. XI. p. 568; “Biog. Générale,” Vol. XXXVI. p. 599.

=A.D. 1749.=--Stukeley (the Rev. William), M.D., is the first who advanced that earthquakes are probably caused by electricity. This he did in a paper read before the Royal Society, March 22, 1749, having reference to the subterranean disturbances noticed in London, February 8 and March 8 of the same year. In this communication, as well as in a subsequent one read to the same Society, December 6, 1750, bearing upon a similar disturbance observed throughout England during the previous month of September, he explains why earthquakes are not the result of subterraneous winds, fires, vapours, etc.

One of his strongest arguments is that no such vapours could instantaneously have destroyed thirteen great cities as did the earthquake which occurred in Asia Minor, A.D. 17, and which is reckoned to have shaken a cone of earth three hundred miles diameter in base and two hundred miles in the axis. This quantity of earth, he says, “all the gunpowder which has ever been made since the invention of it would not have been able to stir, much less any vapours, which could be supposed to be generated so far below the surface,” and, he adds, “if the concussion depended upon a subterraneous eruption the shock would precede the noise.”

He observes that the earth for months prior to the afore-named disturbances “must have been in a state of electricity ready for that particular vibration in which electrification exists”; that all the vegetation had been “uncommonly forward ... and electricity is well known to quicken vegetation”; that the aurora borealis had been very frequent about the same time and had been twice repeated just before the earthquake, “of such colours as had never been seen before,” there being, one evening, “a deep red aurora borealis covering the cope of heaven very terrible to behold”; that the whole year had been “remarkable for fire-balls, thunder, lightning and coruscations, almost throughout all England,” all which “are rightly judged to proceed from the electrical state of the atmosphere”; and, finally, that, a little before the earthquake, “a large and black cloud suddenly covered the atmosphere, which probably occasioned the shock by the discharge of a shower.” He adds that, according to Dr. Childrey, earthquakes are always preceded by rain and sudden tempests of rain in times of great drought.

Dr. Stephen Hales (1677–1761), who was Stukeley’s classmate at Bennet College, Cambridge, and later his chief assistant in the study of the natural sciences, and who afterward became celebrated for his physical investigations and discoveries, arrives at a like conclusion. He thinks that “the electric appearances were only occasioned by the great agitation which the electric fluid was put into by the shock of so great a mass of the earth.” The great noise which attended the disturbance of March 8, 1749, he conjectured was “owing to the rushing or sudden expansion of the electric fluid at the top of St. Martin’s spire, where all the electric effluvia, which ascended along the large body of the tower, being strongly condensed, and accelerated at the point of the weathercock, as they rushed off made so much the louder expansive explosion.” It may be added here that Dr. Hales is the one who, at a previous date, had communicated to the Royal Society his observation of the fact that the electric spark proceeding from warm iron is of a bright, light colour, while that from warm copper is green, and the colour from a warm egg of a light yellow. In his opinion, these experiments appeared to argue that some particles of those different bodies are carried off in the electric flashes wherein those different colours are exhibited.

For Stephen Hales, consult the Phil. Trans., Vol. XLV. p. 409, as well as the abridgments of Hutton, Vol. IX. p. 534, and for his portrait see “Essays in Historical Chemistry,” by T. E. Thorpe, London, 1894.

For Stukeley and for Stephen Hales: consult “General Biographical Dictionary,” Alex. Chalmers, London, 1814, Vol. XVII. pp. 41–43.

REFERENCES.--Priestley, “History of Electricity,” Part I. period x. s. 12; Phil. Trans., abridged by John Martyn, Part II. of Vol. X. pp. 406–526, 535, 540, 541, 551; Vol. XLIV-XLV, p. 409; Appendix to the Phil. Trans. for 1750, Vol. XLVI; Hale, “Statical Essays,” II. p. 291; Thomson, “Hist. Roy. Soc.,” 1812, p. 197.

=A.D. 1749.=--Jallabert (Jean Louis), Professor of Philosophy and Mathematics at Geneva, is the author of “Expériences sur l’électricité, avec quelques conjectures sur la cause de ses effets,” of which a smaller edition had appeared at Geneva in 1748.

He confirms the result obtained by Dr. Watson (A.D. 1745) that the electric fluid takes the shortest course by passing through the substance of a conducting wire instead of along its surface. By making his Leyden experiments with a jar in which the water is frozen, he shows that ice is a conductor of electricity. He improves upon Nollet’s experiments, and demonstrates conclusively that plants which are electrified grow faster and have finer stems, etc., than those not electrified. He is the first to observe that a body pointed at one end and round at the other produces different appearances upon the same body, according as the pointed or the rounded end is presented to it. The Dantzig Memoirs, Vol. II. p. 378, tell us that Carolus Augustus Van Bergen, Professor of Medicine at Frankfort on Oder, had previously noticed, “as a small step toward discovering the effect of pointed bodies,” that sparks taken from a polished body are stronger than those from a rough one. With the latter he found it difficult to fire spirits, but he could easily do it with a polished conductor.

M. Jallabert is also known to have effected some medical cures through the agency of the electric fluid, as related in the “Expériences” above alluded to.

REFERENCES.--“Biog. Univ.,” Vol. XX. p. 535; Bertholon, “Elec. du Corps Humain,” 1786, Vol. I. pp. 260, 292, 299, 334, 413, and Vol. II. p. 291; Beccaria, “Dell’ Elettricismo Naturale,” etc., p. 125; “Journal des Sçavans,” Vol. CXLIX. for 1749, pp. 1–18, 441–461; “Medical Electricity,” by Dr. H. Lewis Jones, Philad. 1904, p. 2.

=A.D. 1749.=--Mines are fired by electricity (S. P. Thompson, lecture delivered October 7, 1882, at the University College, Bristol).

=A.D. 1749.=--Through the important work entitled “Traité sur l’Electricité,” Louis Elisabeth de la Vergne Tressan secures, a year later, admission to both the French Académie des Sciences and the English Royal Society. During 1786, three years after his death, the above-named work was merged into a publication in two volumes under the title of “Essai sur le fluide électrique considéré comme agent universel.”

REFERENCES.--“Biographie Générale,” Vol. XLV. pp. 623–626; Larousse, “Dictionnaire Universel,” Vol. XV. p. 474.

=A.D. 1749.=--Duhamel (Henri Louis, du Monceau) (1700–1782), member of the French Royal Academy of Sciences, develops, in conjunction with M. Antheaulme, the method introduced by Gowin Knight (A.D. 1746) for making artificial magnets, which latter process was found to be defective when applied to very large bars. To Le Maire, however, is due (Mem. de l’Acad. de Paris, 1745 and 1750), the notable improvement which consists in magnetizing at the same time two steel bars of any shape by placing them parallel to each other and connecting their extremities, with pieces of soft iron placed at right angles, in order to form a closed rectangular parallelogram. Two strong magnets, or two bunches of small magnetic bars, with their similar poles together, are then applied to the centre of one of the bars to be magnetized and are drawn away from each other, practically as in Dr. Knight’s method, while being held at an inclination of about forty-five degrees. The operation is repeated upon the other bar and continued alternately until sufficient magnetism is imparted to both, it being borne in mind that before the treatment is given to the second bar the poles must in each instance be reversed, i. e. the pole which was to the right hand should be turned to the left. The entire operation is to be repeated upon the reverse side of both bars.

REFERENCES.--Harris, “Rudim. Magn.,” I. and II. pp. 85 and 86; P. Larousse, “Dict. Univ.,” Vol. VI. p. 1363; “Biog. Générale,” Vol. XV. pp. 106–107; Condorcet, “Eloge de Duhamel”; I. M. Des Essarts, “Siècles littéraires”; Georges Cuvier, “Hist. des Sc. Naturelles,” Vol. V; Thos. Thomson, “Hist. of the Roy. Soc.,” London, 1812, p. 45.

=A.D. 1750–1753.=--In M. Arago’s “Historical Eloge of James Watt,” translated by James P. Muirhead and published in London during the year 1839, it is said, at p. 6, that Watt constructed, at about the period first mentioned herein, a small electrical (his earliest) machine, the brilliant sparks from which became a subject of much amusement and surprise to all the companions of the poor invalid (“James Watt,” by Andrew Carnegie, New York, 1905).

=A.D. 1750.=--Wargentin (Pierre Guillaume--Perh Vilhelm--) (1717–1783), Secretary to the Swedish Academy of Sciences and a distinguished astronomer, addresses, on the 21st of February, a letter to the Royal Society, of which a copy is to be found in Vol. XLVII. p. 126 of the Phil. Trans. In this he gives his observations of the result produced on the magnetic needle by the aurora borealis.

We have already seen (under the A.D. 1683 date), that the discovery of the fact that magnets are affected by the polar lights has been ascribed to Wargentin, and we have also learned (A.D. 1722) that he ascertained the diurnal changes of the magnetic needle with more precision than had been done by George Graham.

REFERENCES.--Walker, “Magnetism,” p. 116; American Journal Science and Arts, 1841, Vol. XXX. p. 227; Celsius, A.D. 1740, and the abridgments of Hutton, Vol. X. p. 165.

=A.D. 1750.=--Michell (John), an eminent English man of science, Professor at Queens’ College, Cambridge, publishes “A treatise of Artificial Magnets, in which is shown an easy and expeditious method of making them superior to the best natural ones.”

The process introduced by this work is known as that of the “double touch.” This consists in first joining, at about a quarter of an inch distance, two bundles of strongly magnetized bars, having their opposite poles together, and in drawing these bars backward and forward upon and along the entire length of the bars to be magnetized, which latter have already been laid down end to end and in a straight line. The operation is to be repeated upon each side of the bars. The central bars of a series thus acquire at first a higher degree of magnetism than do the outer ones, but by transposing the latter and treating all alike the magnetic virtue is evenly distributed. In this process the external bars act the same part as do the pieces of soft iron employed in the Duhamel method.

At Chap. VI. p. 20 of the third volume of his “Rudimentary Magnetism,” Harris thus expresses himself: “Michell advanced the idea that in all the experiments of Hauksbee, Dr. Brooke Taylor, William Whiston and Musschenbroek, the force may really be in the inverse duplicate ratio of the distances, proper allowance being made for the disturbing changes in the magnetic forces so inseparable from the nature of the experiment. He is hence led to conclude that the true law of the force is identical with that of gravity, although he does not set it down as certain.”

REFERENCES.--Harris, “Rud. Mag.,” I. and II. pp. 94–95; C. R. Weld, “Hist. Roy. Soc.,” Vol. I. p. 512; Phil. Trans., Vol. LI. pp. 390, 393, and Hutton’s abridgment, Vol. XI. p. 418; Gaugain’s observations in “Sc. Am. Suppl.,” No. 7, p. 99.

=A.D. 1750.=--Boulanger--not Boullangère--(Nicholas Antoine) (1722–1759), a well-known French writer, whose extensive studies were interrupted by his death, in 1759, at the early age of thirty-seven, gives, in this “Traité de la cause et des phénomènes de l’électricité,” accounts of many important observations made in the electrical field.

His attention was carefully given to ascertaining the degrees in which different substances are capable of being excited, and he gives several lists of such, inferring therefrom that the most transparent and the most brittle are always the most electric.

At pp. 64 and 124 of the above-named “Traité” he states that electricity affects mineral waters much more sensibly than common water; that black ribbons are more readily attracted than those of other colours, next to the black being the brown and deep red; and that, of two glass cylinders exactly alike, except that one is transparent and the other slightly coloured, the transparent one will be the more readily excited.

REFERENCES.--The “Traité,” notably at pp. 135 and 164; “Biog. Générale,” Vol. VI. p. 939; Le Bas, “Dict. Encycl. de la France”; Quérard, “La France Littéraire”; Chaudon et Delandine, “Dict. historique.”

=A.D. 1751.=--Adanson (Michael), a French naturalist of very high reputation, who, before the age of nineteen, had actually described four thousand species of the three kingdoms of nature, introduces in his “History of Senegal” the silurus electricus, a large species of eel originally brought from Surinam. Sir John Leslie states that the silurus is furnished with a very peculiar and complex nervous apparatus which has been fancifully likened to an electrical battery, and that, from a healthy specimen exhibited in London, vivid sparks were drawn in a darkened room. M. Broussonet alludes to the silurus as Le Trembleur in the “Hist. de l’Acad. Royale des Sciences” for 1782, p. 692.

Adanson also called attention, in 1756, to the electrical powers of the malapterus electricus, but, according to the able naturalist, James Wilson (“Ichthyology,” Encycl. Brit.), there is a much earlier account of the fish extracted from the narrative of Baretus and Oviedo dated 1554.

The Swedish scientist, Karl A. Rudolphi, pupil of Linnæus, called the princeps helminthologorum, has given a detailed description as well as illustrations of the electric organs of the malapterus in “Ueber den Zitter-wels,” Abh. Berl. Acad. VII.... This fish, which the Arabs call Raad or Raash (thunder), gives its discharge chiefly when touched on the head, but is powerless when held by the tail, the electrical organs in fact not reaching the caudal fin.

To Adanson has been attributed the authorship of an essay on the “Electricity of the Tourmaline” Paris, 1757, which bears the name of the Duke de Noya Caraffa.

REFERENCES.--Spreng, “Hist. R. Herb.,” Vol. II; and “Adanson’s Biog.,” Vol. II. “Encycl. Britannica,” Rees’ “Cycl.” Supplement and in “Bibl. Universelle,” Vol. I; Chambers’ “Encyl.” for 1868, Vol. III. p. 822; Cavallo, “Nat. Phil.,” Philad., 1825, Vol. II. p. 237; Scientific American Supplement, No. 457, pp. 7300, 7301; Rozier, Vol. XXVII. p. 139, and W. Bryant in Trans. Am. Phil. Soc. II. p. 166, O. S.

=A.D. 1752.=--Franklin (Benjamin) (1706–1790), an able American editor, philosopher and statesman, crowns his many experiments with the brilliant discovery of the identity of electricity and lightning. Humboldt says: “From this period the electric process passes from the domain of speculative physics into that of cosmical contemplation--from the recesses of the study to the freedom of nature” (“Cosmos,” Vol. II. 1849, p. 727). Wall (A.D. 1708) had only alluded to the resemblance of electricity to thunder and lightning; Grey (A.D. 1720) had conjectured their identity and implied that they differed only in one degree, while Nollet (A.D. 1746) pointed out a closer relationship than ever before adduced between lightning and the electric spark; but it was left for Franklin to prove the fact with empirical certainty.

Franklin’s attention was first directed to electrical studies in 1745, by a letter from Peter Collinson, Fellow of the Royal Society of London, to the Literary Society of Philadelphia, and he first wrote on the subject to that gentleman on the 28th of July, 1747. This was followed by several other similar communications up to April 18, 1754, the whole of which comprise most of what subsequently appeared under the title “New Experiments and Observations on Electricity, made at Philadelphia, in America, by Benjamin Franklin, LL.D. and F.R.S.”

Franklin first entertained the idea that lightning was not likely to be attracted by a pointed rod unless the latter was placed at a great height, and he therefore waited for the erection of a tall spire in Philadelphia which he intended to utilize for his observations, but delay in its completion led him to use a kite pointed with an iron rod, not doubting that the electric fluid could, during a thunderstorm, be drawn from it through a string.

The manner of constructing and employing the kite, and the attending results, are thus given in a letter dated Oct. 19, 1752 (Letter XII, “Experiments and observations on Electricity”): “Make a small cross of two light strips of cedar, the arms so long as to reach to the four corners of a large thin silk handkerchief when extended. Tie the corners of the handkerchief to the extremities of the cross, so you have the body of a kite which, being properly accommodated with a tail, loop and string, will rise in the air like those made of paper; but, this being made of silk, is fitter to bear the wet and wind of a thunder-gust without tearing. To the top of the upright stick of the cross is to be fixed a very sharp-pointed wire, rising a foot or more above the wood. In the end of the twine, next the hand, is to be held a silk ribbon, and where the silk and twine join a key may be fastened. This kite is to be raised when a thunder-gust appears to be coming on, and the person who holds the string must stand within a door or window, or under some cover, so that the silk ribbon may not be wet, and care must be taken that the twine does not touch the frame of the door or window. As soon as any of the thunder clouds come over the kite, the pointed wire will draw the electric fire from them, and the kite with all the twine will be electrified, and the lose filaments of the twine will stand out every way and be attracted by an approaching finger. And when the rain has wetted the kite so that it can conduct the electric fire freely, you will find it stream out plentifully from the key on the approach of your knuckle. At this key, the phial (Leyden jar) may be charged, and from electric fire thus obtained spirits may be kindled, and all the other electric experiments be performed which are usually done by the help of a rubber glass globe or tube, and thereby the sameness of the electric matter with that of lightning completely demonstrated.”

It was during the month of June 1752, on the approach of a storm, that he and his son walked out upon the Philadelphia Commons and first raised the kite. At the outset no important results were obtained, but as soon as the cord became wet by the shower that followed, the electric sparks were easily drawn from the key and enabled Franklin to charge and give shocks from a Leyden jar.

Thus, says Sabine, was Benjamin Franklin successful in one of the boldest experiments ever made by man upon the powers of nature, and from that moment he became immortal.

He had already, in 1749, made public the following, which is embodied in one of his letters to Mr. Collinson: “The electrical spark is zigzag, and not straight; so is lightning. Pointed bodies attract electricity; lightning strikes mountains, trees, spires, masts and chimneys. When different paths are offered to the escape of electricity, it chooses the best conductor; so does lightning. Electricity fires combustibles; so does lightning. Electricity fuses metals; so does lightning. Lightning rends bad conductors when it strikes them; so does electricity when rendered sufficiently strong. Lightning reverses the poles of a magnet; electricity has the same effect.”

Franklin had, likewise, published at about the same period the plan for an experiment to ascertain from elevated structures whether the clouds that contain lightning are electrified or not. He himself had proposed to put the plan to execution; but he was led to try the kite experiment, and, meanwhile, his suggestions had been successfully acted upon, in France, by M. Dalibard and de Lor, as will be shown later on.

“The lightning, which doth cease to be, ere one can say, ‘it lightens.’”--Shakespeare.

“First let me talk with this philosopher; what is the cause of thunder?”--Shakespeare.

“... a way for the lightning of the thunder.”--Job xxviii. 26, and xxxviii. 25.

“It related not to the instances of the magneticalness of lightning.”--“Hist. of Roy. Soc.,” by Thomas Birch, Vol. IV. p. 253.

When specifying the great points of coincidence existing between the ordinary electric discharge and lightning, Franklin, as already partly stated, had remarked that flashes of lightning are frequently waving and crooked, of a zigzag or forked appearance, sometimes diffused and sometimes coloured (“On the Nature of Thunderstorms,” W. Snow Harris, London, 1843, p. 24; Priestley, “History and Present State of Electricity,” London, 1769, p. 166; “Encycl. Metropol.,” article “Electricity”; Biot, “Traité de Physique,” Vol. II). In treating of the subject of lightning flashes, Dr. L. D. Gale (trans. of M. F. J. F. Duprez’s paper on “Atmospheric Electricity,” taken from the memoirs of the Royal Academy of Brussels) alludes to the attempts made by C. G. Helvig to determine the velocity of the linear flashes (Gilbert’s Annalen, Vol. LI. pp. 136 and 139, ss. 2, 10) which he estimated to be 40,000 to 50,000 feet in a second, and states that M. Weigsenborn, of Weimar (Comptes Rendus, Vol. IX. p. 218), calculated the velocity of a flash observed in 1839 to be more than two leagues, while M. François Arago (“Annuaire,” etc., pour l’année 1838, pp. 249, 255, 257, 459, estimated the lengths of certain flashes to be 3·3, 3·6, 3·8 leagues. The views of Messrs. Logan (Phil. Trans., 1735, Vol. XXXIX. p. 240), L. J. Gay-Lussac (Ann. de Chim. et de Phys., 1805, Vol. XXIX. p. 105), H. W. Brandes (“Beiträge zur Witterungskunde,” etc., 1820, p. 353), C. H. Pfaff and L. E. Kaemtz (J. S. T. Gehler, “Dict. de Phys.,” Vol. I. p. 1001, and “Lehrbuch d. Meteor,” Vol. II. p. 430), Gabriel Lamé (“Cours. de Phys. de l’Ecole Polytech.,” Tome II. 2^e partie, p. 82), Becquerel (Comptes Rendus, 1839, Tome VIII. p. 216), Faraday (Philos. Magazine, 1841, Vol. XIX. p. 104), Pouillet (“Eléments de Phys. et de Météor,” Tome II. p. 808), Parrot (J. S. T. Gehler, “Dict. de Phys.,” Vol. I. p. 999), are also set forth in the above-named translation of M. Duprez’s valuable work.

Humboldt informs us that “the most important ancient notice of the relations between lightning and conducting metals is that of Ctesias, in his Indica, Cap. IV. p. 169. He possessed two iron swords, presents from the King Artaxerxes Mnemon, and from his mother Parysatis, which, when planted in the earth, averted clouds, hail and strokes of lightning. He had himself seen the operation, for the king had twice made the experiment before his eyes” (“Cosmos,” Vol. II. N. 186). Ctesias was a man of great learning. He was a contemporary of Xenophon, and lived for a number of years at the Court of Artaxerxes Mnemon as private physician to the king. Diodorus states that Ctesias was highly honoured at the Persian court. An abridged edition of the Indica was printed by Stephens in 1594 (“Hist. Roy. Soc.,” C. R. Weld, London, 1848, Vol. II. p. 93; “La Grande Encyclopédie,” Vol. XIII. p. 536; “Biographie Générale,” Vol. XII. p. 568).

In imitation of Franklin, Doctor Lining, of Charleston, in South Carolina, sent a kite into a thunder cloud, and by that means dissipated the lightning (Philosophical Transactions for 1754, Vol. XLVIII. p. 757).

The opinion entertained by Franklin regarding the nature of electricity differs from that previously submitted by Dufay (A.D. 1733), in the manner shown by Noad at p. 6 of his Manual, London, 1859 edition.

What Dufay considered to be two distinct species of electricities, vitreous and resinous, Franklin conceived to be two different states of the same electricity, which he called positive and negative. This, which constitutes the foundation of the present theory of electricity, is usually called the Franklinian theory, but it can be said to belong equally to Dr. Watson, for he had communicated it to the Royal Society before Franklin’s opinion on the subject was known in England (Phil. Trans. for 1748, Vol. XLV. pp. 49, 491; Thomson, “Hist. Roy. Soc.,” p. 436). Noad, in paragraph 12, applies the latter theory to the case of a charged Leyden jar, alluding to Franklin’s discovery of the location of electricity in the jar, wherefrom is drawn the conclusion that it is upon the glass that the electricity is deposited, and that the conducting coatings serve “only, like the armature of the loadstone, to unite the forces of the several parts and bring them at once to any point desired” (see “Œuvres de Franklin,” trans. of Barbeu-Dubourg, Tome II. p. 16, 3^e lettre).

Of his plus and minus theory, Franklin thus wrote to Mr. Collinson: “To electrise plus or minus no more needs to be known than this, that the parts of the tube or sphere that are rubbed do, in the instant of the friction, attract the electrical fire, and therefore take it from the thing rubbing; the same parts, immediately as the friction upon them ceases, are disposed to give the fire they have received to any body that has less.”

In an appendix to his official report as U.S. Commissioner at the Paris Universal Exposition of 1867, entitled “Franklin and Electrical Semaphores,” Professor Samuel F. B. Morse, LL.D., expressed himself as follows:

“It has frequently been asserted (on what authority I know not) that the first idea of an electric semaphore originated with Franklin. I have sought in vain in the publication of Franklin’s experiments and works for anything confirmatory of this assertion. On mentioning the subject to my friend Professor Blake, he kindly proposed examining the writings of Franklin in order to elicit the truth. From him I have received the following:

“‘I consulted several works for the purpose of ascertaining, if possible, the foundation for the statement that Franklin suggested the idea of semaphores by static electricity. I have not yet found any such suggestion, but I have noted that, following the experiments by Dr. Watson and others, in England, to determine the velocity of the electric discharge, and the time supposed to be required for the electrical discharges across the Thames, by which spirits were kindled, etc. (in 1747), Dr. Franklin (in 1748) made some similar experiments upon the banks of the Schuylkill, and amused his friends by sending a spark “from side to side through the river without any other conductor than the water” (vide Priestley’s “History of Electricity”). This was in 1748, at the end of the year. In 1756 “J. A., Esq.,” of New York (James Alexander), presented to the Royal Society a proposition “to measure the time taken by an electric spark in moving through any given space” by sending the discharge or spark down the Susquehanna or Potomac, and round by way of the Mississippi and Ohio rivers, so that the “electric fire” would have a circuit of some thousands of miles to go. All this was upon the supposition or assumption that the electric fire would choose a continuous water conductor rather than to return or pass through the earth. Franklin presented a paper in reply, in which he says “the proposed experiment (though well imagined and very ingenious) of sending the spark round through a vast length of space, etc. etc., would not afford the satisfaction desired, though we could be sure that the motion of the electric fluid would be in that tract, and not underground in the wet earth by the shortest way”’ (‘Franklin’s Experiments on Electricity, and Letters and Papers on Philosophical Subjects,’ 4to, London, MDCCLXIX, pp. 282, 283).

“Can it be possible that Franklin’s experiment of firing spirits and showing the spark and the effects of the electric discharge across the river originated, or forms the foundation for, the statement that he suggested the semaphoric use of electricity?”

After speaking of the experiments, to which allusion was made (at Watson, A.D. 1745), Franklin writes: “... It is proposed to put an end to them for this season, somewhat humorously, in a party of pleasure, on the banks of the Schuylkill. Spirits at the same time are to be fired by a spark sent from side to side through the river without any other conductor than the water--an experiment which we some time since performed to the amazement of many. A turkey is to be killed for our dinner by the electrical shock, and roasted by the electrical jack, before a fire kindled by the electrified bottle, when the healths of all the famous electricians in England, Holland, France and Germany are to be drank in electrified bumpers under the discharge of guns from the electrical battery.”

It was toward the close of the year 1750 that Franklin entertained the practicability of a lightning conductor (see Winckler, A.D. 1733), and, for this, he says, he was indebted to an experiment made by his friend Mr. Thomas Hopkinson (vide Franklin’s “Complete Works,” London, 1806, Vol. I. p. 172). In his “Poor Richard’s Almanac” for 1753, he refers to the lightning rod as security for “habitations and other buildings from mischief by thunder and lightning.”

REFERENCES.--J. B. Le Roy, “Lettera al Rozier,” etc., Milano, 1782; “Rec. de Mém. de l’Acad. des Sc.” for 1770 and 1773; Jour. de Phys., 1773, Vol. II; Memoirs of M. Beyer, Paris, 1806–1809, and Delaunay’s explanation of his theories at pp. 193–198 of his 1809 Manuel.

The many notable observations, experiments and discoveries of Franklin are nowhere more ably reviewed than by his great admirer Dr. Priestley, who devotes much space thereto in his justly celebrated work on electricity.

At p. 92 of his “New Experiments,” etc., London, 1774, Franklin alludes to the failure of many European electricians in firing gunpowder by the electric spark, and gives his own method by using a battery of four large glass jars, while at p. 423 of the London edition of his “Letters and Papers,” etc., Franklin relates curious observations which are worth mentioning here. He says that he sent a charge of electricity “through a small glass tube that had borne it well when empty, but when filled with water was shattered to pieces and driven all about the room. Finding no part of the water on the table, I suspected it to have been reduced to vapour. I was confirmed in that suspicion afterward when I had filled a like piece of tube with ink and laid it on a sheet of paper, whereon after the explosion I could find neither any moisture nor any sully from the ink. This experiment of the explosion of water, which I believe was first made by that most ingenious electrician, Father Beccaria, may account for what we sometimes see in a tree struck by lightning, when part of it is reduced to fine splinters like a broom; the sap vessels being so many tubes containing a watery fluid, which, when reduced to vapour, sends every tube lengthways. And, perhaps it is this rarefaction of the fluids in animal bodies killed by lightning or electricity, that by separating its fibres renders the flesh so tender and apt so much sooner to putrefy. I think, too, that much of the damage done by lightning to stone and brick walls may sometimes be owing to the explosion of water found during showers, running or lodging in the joints or small cavities or cracks that happen to be in the walls.”

REFERENCES.--Majus--May--(Heinrich), “Disp. de fulmine” and “Disp. de tonitru,” Marp., 1673, as at Pogg., Annalen, Vol. II. p. 21; Giuseppe Saverio Poli, “La formazione del Tuono,” etc., 1772, and his other works on the same subject which appeared during the years 1773, 1779 and 1787; Phil. Trans. for 1751, Vol. XLVII. pp. 202, 289, 362; W. de Fonvielle, “Eclairs et Tonnerres”; “Terrestrial Magn.” for June 1903; Jour. of the Franklin Institute for 1836, Vol. XVII., p. 183; M. le Docteur Sestier, “De La Foudre”; “Lightning-Rod Conference,” Reports of Delegates, by G. J. Symons, 1882; Chap. III. s. 3, vol. i. of Van Swinden’s “Recueil,” etc., 1784; Lumière Electrique, Tome XL. No. 23, p. 497; Giovanni Cardan’s work, Lyons, 1663; “Library of Literary Criticism,” C. W. Moulton, Buffalo, 1901–1902, Vol. IV. pp. 79–106; “An Outline of the Sciences of Heat and Electricity,” by Thos. Thomson, London, 1830, pp. 347, 423, 432–433; “The Electrical Researches of the Hon. Henry Cavendish,” Cambridge, 1879, Nos. 350, note, 363; “Works of Benj. Franklin,” Jared Sparks, London, 1882; Phil. Trans., Vols. XLVII. p. 565; XLIX. pp. 300, 305,; L. p. 481; LI. p. 525; LII. 456; also Hutton’s abridgments, Vol. X. pp. 189, 212, 301, 629, 632; Vol. XI. pp. 189, 435, 609; “Bibliothèque Britannique,” Genève, 1796, Vol. LI. p. 393 (letter to M. Marc Auguste Pictet); Stuber, “Continuation of the Life of Dr. Franklin”; “An Essay on the Nature of Heat, Light and Electricity” (on the Franklinian hypothesis), by Chas. Carpenter Bompass, London, 1817, Chap. III. s. 3, p. 217; “List of Books written by or relating to Franklin,” by Paul L. Ford, 1889; L. Baldwin, “Mem. of Amer. Acad.,” O. S. I. part i. p. 257; Sturgeon’s “Researches,” p. 524; J. Bart. Beccari, “De Artif. elect ...”; likewise all the references that are given at pp. 26–27 of Ronalds’ “Catalogue”; “Journal des Savants” for June 1817, pp. 348–356.

=A.D. 1752.=--Dalibard (Thomas François), French botanist and amateur in physics, carries out very carefully the suggestions embodied in Franklin’s printed letters and constructs an atmospherical conductor at Marly-la-Ville, about eighteen miles from Paris, where Nollet likewise experimented. Dalibard’s apparatus consisted of a pointed iron rod, one inch in diameter and about forty feet long, which was protected from the rain by a sentry box and attached to three long wooden posts insulated by silken strings.

On the 10th of May, 1752, during Dalibard’s absence, an old soldier by the name of Coiffier, who was at the time employed as a carpenter and who had been left in charge, on observing the approach of a storm, hurried to the apparatus prepared to carry out the instructions previously given him. It was not long before he succeeded in obtaining large sparks on presenting a phial to the rod, and these sparks, which were all accompanied by a large snapping noise, were likewise obtained by the curate of Marly, M. Raulet, whom he had sent for and with whose aid Coiffier subsequently succeeded in charging an electric jar. On the 13th of May, Dalibard made, to the French Academy of Sciences, a report of the results thus obtained by Coiffier, to whom, it may be said, properly belongs the distinction of having been the first man who saw the electric spark drawn from the atmosphere.

On the 18th of the same month of May, M. de Lor, of the French University, drew similar sparks from a rod ninety-nine feet high at his house in the Estrapade, at Paris, and the same phenomenon was afterward exhibited to the French King. It is said that the conductor afforded sparks even when the cloud had moved at least six miles from the place of observation. Other experiments of a like nature were made a few days later by Buffon at Montbar, and, during the ensuing months of July and August, in the vicinity of London, by Canton, who, it is said, succeeded in drawing atmospheric electricity by means of a common fishing rod (Dissertation Fifth, Eighth “Britannica,” Vol. I).

An account of the Dalibard and de Lor experiments was transmitted by the Abbé Mazéas, on the 20th of May, to the Royal Society of London.

Mazéas erected, in the upper section of his residence, a magazine consisting of several insulated iron bars connected with the pointed rod. The lightning was brought into the house by means of a projecting wooden pole, having at its extremity a glass tube filled with resin which received a pointed iron rod twelve feet long. This apparatus was, however, too much exposed to afford reliable observations, and Mazéas therefore arranged to make more accurate experiments at the Château de Maintenon, during the months of June, July and October 1753. The results he obtained were communicated to the English Royal Society by Dr. Stephen Hales. The letters of the Abbé Mazéas to the Rev. Stephen Hales, detailing some of M. Le Monnier’s experiments as well as observations made by M. Ludolf at Berlin and transmitted by M. Euler, are to be found at pp. 354–552, Vol. XLVII. Phil. Trans. for 1753. For Mazéas, see also Phil. Trans., Vol. XLVII. p. 534, Vol. XLVIII. part i. p. 377, and Hutton’s abridgments, Vol. X. pp. 289, 434.

Thomas Ronayne in Ireland, and Andrew Crosse[51] in England (see “Account of an apparatus for ascertaining and collecting the electricity of the atmosphere”) made use of long wires in horizontal positions insulated by being attached to glass pillars, but Mazéas, in his Maintenon experiments, attached the iron wire by a silken cord to the top of a steeple ninety feet in height, whence it entered an upper room of the castle, a total distance of 370 feet. With this, Mazéas ascertained that electric effects are produced at all hours of the day during clear, dry and particularly hot weather, the presence of a thunderstorm not being requisite for the production of atmospheric electricity. In the driest summer nights he could discover no signs of electricity in the air, but when the sun reappeared the electricity accompanied it, to vanish again in the evening about half an hour after sunset.

REFERENCES.--W. Sturgeon, “Lectures,” London, 1842, pp. 182, 183; Phil. Trans., Vol. XLVIII. part i. pp. 370, 377, etc.; Dalibard’s “Franklin,” Vol. II. p. 109, etc.; “Mém. de l’Acad. des Sciences,” for May, 1762; Nollet, “Letters,” Vol. I. p. 9; Franklin’s Works, Vol. V. p. 288; English Cyclopædia, “Arts and Sciences,” Vol. III. pp. 804–805; “Letters of Thomas Ronayne, to Benjamin Franklin,” at p. 137 of Vol. LXII of Phil. Trans., likewise Ronayne both in Journal de Physique, Tome VI, and in the Phil. Trans. for 1772, Vol. LII. pp. 137–140; also Hutton’s abridgments, Vol. XIII. p. 310; Geo. Adams, “Essay on Elect.,” London, 1785, p. 259.

=A.D. 1752.=--Freke (John), surgeon to St. Bartholomew’s Hospital, London, gives, in the Second Part of “A Treatise ... of Fire,” the third edition of his “Essay to Show the Cause of Electricity,” etc., originally published in 1746, while in the Third Part of the same work he shows the “Mechanical Cause of Magnetism, and why the compass varies in the manner it does.”

He says (pp. 90–91): “It had been impossible that this wonderful Phenomenon of Electricity should ever have been discovered, if there had not been such things as are non-electricable; for, as fast as this Fire had been driven on anything its next neighbour would have carried it farther; but, when it was most wonderfully found, that anything which was suspended on a silk cord (that being non-electricable) was obliged to retain the Fire, which by Electrical Force was driven on it; and when, moreover, it appeared, that any person or thing, being placed on a cake of beeswax (which is also a non-electricable) could no more part with its Fire than when suspended in [sic] a silk cord; I think it will become worthy of inquiry, why they are not electricable.” And, at p. 136, he adds: “I think it a great pity that the word Electricity should ever have been given to so wonderful a Phenomenon, which might properly be considered as the first principle in nature. Perhaps the word Vivacity might not have been an improper one; but it is too late to think of changing a name it has so long obtain’d.” In the Third Part, he explains that “by the Fire passing from and to the Sun, it so pervades iron aptly placed, as to make it attractive and produce the various operations of magnetism.”

REFERENCE.--“Gentleman’s Magazine,” London, Vol. XVI for 1746, pp. 521, 557.

=A.D. 1752.=--In this year was published at Leipzig the “Biblia Naturæ,” written by John Swammerdam, a celebrated Dutch natural philosopher (1637–1682), all of whose works were translated into English and published in folio during the year 1758.

In the second volume of the Biblia, he thus alludes to one of many experiments made by him in 1678, before the Grand Duke of Tuscany: “Let there be a cylindrical glass tube in the interior of which is placed a muscle, whence proceeds a nerve that has been enveloped in its course with a small silver wire, so as to give us the power of raising it without pressing it too much or wounding it. This wire is made to pass through a ring bored in the extremity of a small copper support and soldered to a sort of piston or partition; but the little silver wire is so arranged that on passing between the glass and the piston the nerve may be drawn by the hand and so touch the copper. The muscle is immediately seen to contract.”

Through Swammerdam, the Germans lay claim to the origin of what has been called galvanism. It certainly cannot be denied that the above-described experiment closely resembles that which made Galvani famous (A.D. 1786).

REFERENCES.--Swammerdam’s Biography, also Dissertation Fifth, in the eighth edition “Encycl. Brit.”; the note at p. 491 of Ronalds’ “Catalogue”; “Gen. Biog. Dict.,” London, 1816, Vol. XXIX. pp. 45–47; Eloy, “Dict. Hist. de la Méd.,” Vol. IV; “Biog. Générale,” Vol. XLIV. pp. 706–708; Cuvier, “Hist. des Sc. Naturelles,” Vol. II. pp. 427–433; Schelhorn, “Amænitates liter.,” Vol. XIV; “Biblioth. Hulthemiana,” Gand, 1836, Vol. II; Boerhaave, Preface to “Biblia Naturæ.”

=A.D. 1752.=--On the 16th of April, 1752, is read before the Royal Society a letter written by John Smeaton, a very prominent English engineer and inventor (1724–1792), to Mr. John Ellicot, giving an account of the electrical experiments in vacuo made with his improved air pump at the request of Mr. Wilson. This account, fully illustrated, appears in the Society’s Vol. LXVII for the years 1751 and 1752, pp. 415–428.

He observes that, upon heating the middle of a large iron bar to a great heat, the hot part can be as strongly electrified as the cold parts on each side of it. He also finds that if anybody who is insulated presses the flat part of his hand heavily against the globe, while another person standing upon the floor does the same, in order to excite it, the one who is insulated will hardly be electrified at all; but that, if he only lays his fingers lightly upon the globe, he will be very strongly electrified.

REFERENCES.--Wilson, “Treatise on Electricity,” pp. 129–216; Phil. Trans. XLVI. p. 513; “Dict. of Nat. Biography,” Vol. LII. pp. 393–395; “Biog. Univ.” (Michaud), Vol. XXXIX. p. 445; Smile’s “Lives of the Engineers--Smeaton and Rennie”; Flint’s “Mudge Memoirs,” Truro, 1883.

=A.D. 1752–1753.=--M. de Romas, Assessor to the Presideal of Nerac, in France, repeats the experiment of Benjamin Franklin, and succeeds finally in bringing from the clouds more electricity than had before been taken by any apparatus.

He constructed a kite seven feet five inches high and three feet wide, with a surface of eighteen square feet, and, having wound fine copper wire around a strong cord through its entire length of about eight hundred feet, he raised the kite to a height of five hundred and fifty feet on the 7th of June, 1753. Sparks two inches in length were at first drawn by a discharging rod, and, when the kite was afterwards allowed to reach an elevation of six hundred and fifty feet, he received many flashes one foot long, three inches wide and three lines diameter, accompanied by a noise audible at as great a distance as five hundred feet.

On the 16th of August, M. de Romas raised the kite with about one thousand feet of string and obtained thirty beams of fire, nine or ten feet long and about an inch thick, accompanied by a noise similar to that of a pistol shot (“Encycl. Britannica,” eighth edition, Vol. VIII. p. 582). Three years later, August 26, 1756, and also during the year 1757, De Romas obtained similar results from numerous experiments. He finally apprehended much danger from the raising of the kite and thereafter coiled the string upon a small carriage, which he drew along by means of silken lines as the cord was being unwound.

The researches of De Romas concerning the electricity of isolated metallic bars are embraced in six letters addressed by him to the Bordeaux Academy of Sciences between July 12, 1752, and June 14, 1753. It is reported that they have never been printed and that they are kept, together with other manuscript matter of the same physicist, in the private archives of the institution.

The experiments of De Romas upon isolated bars were first repeated by Boze at Wittenberg, by Gordon at Erfurt, and by Lomonozow in Russia (Phil. Trans., Vol. XLVIII. part ii. p. 272). M. Veratti, of Bologna, obtained the electric spark in all weathers, through a bar of iron resting in sulphur, and Th. Marin, of the same city, by means of a long iron pole erected upon his dwelling, studied the relationship of rain and atmospheric electricity (Musschenbroek, “Cours de Physique” Vol. I. p. 397).

REFERENCES.--Journal des Sçavans for October, 1753, p. 222; “Mémoire sur les moyens,” etc., par De Romas, Bordeaux, 1776; Sturgeon’s “Annals,” etc., Vol. V. p. 9; Harris, “Electricity,” p. 176; Priestley, “History,” etc., 1775, pp. 326–329; “Mémoires de Mathématique,” etc., Vol. II. p. 393, and Vol. IV. p. 514; “Etude sur les travaux de De Romas,” p. 491, by Prof. Mergey, of Bordeaux, which latter work won a prize for its author in 1853; Becquerel, “Traité expérimental,” etc., 1834, Vol. I. pp. 42–43; likewise the results obtained by Prof. Charles in “Traité de Physique Expérimentale,” etc., par Biot, Paris, 1816, Vol. II. pp. 444, 446, and in Peltier’s Introduction to his “Observations et Recherches Expérimentales,” etc., Paris, 1840, p. 7, as well as Brisson’s “Dict. de Phys.,” Paris, 1801, Vol. II. p. 174, and “Mémoires des Savants Etrangers,” 1755, Vol. II. p. 406.

=A.D. 1753=.--M. Deslandes, member of the French Royal Academy of Sciences, is the author of “Recueil de Différents traités de Physique,” the third volume of which contains his memoir on the effects of thunder upon the mariner’s compass. He alludes to the observations made thereon by Dr. Lister of London (well known by his “Historiæ Animalium Angliæ,” Lugd., 1678), as well as to many experiments made by Musschenbroek and by others noted in the Philosophical Transactions.

=A.D. 1753.=--Prof. George William Richmann (1711–1753), native of Sweden and member of the Imperial Academy of St. Petersburg, who had already constructed an apparatus for obtaining atmospherical electricity according to Franklin’s plans, was attending a meeting of the Russian Academy of Science, on the 6th of August, 1753, when his ear caught the sound of a very heavy thunder clap. He hastened away in company with his engraver, M. Sokolow, and upon their arrival home they found the plummet of the electrometer elevated four degrees from the perpendicular. Richmann stooped toward the latter to ascertain the force of the electricity, and “as he stood in that posture, a great white and bluish fire appeared between the rod of the electrometer and his head. At the same time a sort of steam or vapour arose, which entirely benumbed the engraver and made him sink on the ground.” Sokolow recovered, but Richmann had met with instant death.

REFERENCES.--“Library of Useful Knowledge,” London, 1829; “Electricity,” p. 59, also p. 33; “Lettre sur la mort de Richmann,” par C. A. Rabiqueau, Paris, n. d.; “Comment. Acad. Petrop.,” XIV. pp. 23, 301–302, also the “Novi Comment.,” IV. pp. 25, 235 and 299; “Biog. Générale,” Vol. XLII. p. 258; “Gentleman’s Magazine,” London, Vol. XXIII., 1753, p. 431 and Vol. XXV. for 1755, p. 3; Singer, “Electricity,” p. 217; Harris, “Electricity,” p. 177; Phil. Trans., Vol. XLVIII. part ii. pp. 763–765, 772; also Vol. XLIX. part i. pp. 61, 67, and the abridgments by Hutton, Vol. X. pp. 525, 574–577; “La physique à la portée de tout le monde,” par le Père Paulian, Vol. II. p. 357; “Hist. de l’Acad. des Sciences,” pour 1753, p. 78; “Franklin in France,” 1888, Part. I. p. 5.

=A.D. 1753.=--Canton (John), an English savant (1718–1772), announces his most important discovery that vitreous or resinous electricity may be produced at will in the same tube. This he proves on taking a tube, which had been roughened by grinding it with thin sheet-lead and flour-of-emery mixed with water, and which developed vitreous electricity when rubbed with dry oil silk, and resinous or negative electricity when rubbed with new flannel. Rough quartz will, it is said, show like results. He also took a tube, of which only one-half had been made rough while the other half was polished, and he demonstrated that the different electricities are produced at a single stroke with the same rubber.

He likewise discovered that the exciting power of the rubber or cushion of the electrical machine will be very greatly increased by applying to it an amalgam of mercury and tin mixed with a little chalk or whiting (see Winckler, at A.D. 1733, for the introduction of the cushion).

His very remarkable experiments upon many descriptions of tourmaline, reported to the Royal Society in December 1759, were followed by many others detailed by Priestley, at pp. 298–301 of his “History of Electricity,” London, 1775, and Canton was the first to discover the electrical properties of the topaz, which latter were made known during the early part of the year 1760. (Consult Wilhelm Hankel, “Uber die therm. eigen. des Topases,” Leipzig, 1870.)

He was also the first to establish properly the fundamental fact of electrification by induction, or, as he terms it, “relating to bodies immerged in electric atmospheres,” which afterward led Wilcke (A.D. 1757) and Æpinus (A.D. 1759) to the method of charging a plate of air like a plate of glass, and to make the most perfect imitation of the phenomena of thunder and lightning (George Adams, “Essay on Electricity,” London, 1799, pp. 351–356; Noad, “Manual,” Chapter I, and Priestley, “History,” etc., s. 5). The paper containing an account of Canton’s experiments was read before the Royal Society, December 6, 1753. The principle enounced is that “the electric fluid, when there is a redundancy of it in any body, repels the electric fluid in any other body when they are brought within the sphere of each other’s influence and drives it into the remote parts of the body; or quite out of it, if there be any outlet for that purpose. In other words, bodies immerged in electric atmospheres always become possessed of the electricity contrary to that of the body in whose atmosphere they are immerged.”

Canton is the first to show that the air of a room can be electrified either positively or negatively, and can be made to retain the electricity when received. He thus explains his method: “Take a charged phial in one hand and a lighted candle insulated in the other, and, going into any room, bring the wire of the phial very near to the flame of the candle and hold it there about half a minute, then carry the phial and candle out of the room and return with the pith balls (suspended by fine linen threads) held out at arm’s length. The balls will begin to separate on entering the room and will stand an inch and a half or two inches apart when brought near the middle of it.”

The construction of artificial magnets by Canton, through the combination of the Duhamel (A.D. 1749) and the Michell (A.D. 1750) methods, as well as without the aid of natural loadstones or artificial magnets, is detailed by Noad at Chapter XV of his “Manual,” London, 1859.

REFERENCES.--Phil. Trans., Vol. XXXV. p. 137 (Berlinghieri, V. L.); Vol. XXXVII. p. 294 (Marcel, A.); Vol. XLVII. p. 31; Vol. XLVIII. part i. pp. 350, 356, and Part II. pp. 780, 782 and 784, also Vol. XLIX. part i. p. 300; Vol. LI. pp. 398, 403, and Vol. LII. part ii. pp. 457, 461; and the abridgments of Hutton, Vol. X. pp. 131, 421, 532; Vol. XI. pp. 421, 609; A.D. 1722, and A.D. 1752; “A Course of Lectures on Nat. Philos. and the Mechanical Arts,” by Thos. Young, London, 1807, Vol. I. p. 372; II. pp. 64, 243; “The Electrical Researches of Hon. Hy. Cavendish,” 1879, Nos. 117, 205; Descriptions and Drawings of the various electric friction machines can be seen in Priestley’s “History,” Plates IV-VIII, and in Albrecht’s “Geschichte d. Electricität,” 1885, pp. 20–30; Acta Acad. Petr., I., 1778; “Gentleman’s Magazine” for Sept. 1759. See likewise the Phil. Trans. for Monday, January 21, 1666, p. 375, and George Adams’ “Essay on Electricity,” etc., London, 1799, p. 579, for method of making the artificial Bolonian stone or Canton’s phosphorus.

=A.D. 1753.=--Beccaria (Giovanni Baptista) (1716–1781), a very ingenious and industrious Italian electrician and astronomer, is the author of several quite important works on electricity.

Father Beccaria, as he is sometimes called from having been a member of the religious order of the Pious Schools, proved at the time to be the most indefatigable follower of Franklin in the study of atmospheric electricity. He was the first who recorded the phenomena of thunderstorms, and his many observations thereon are detailed throughout Part I. period x. and s. 10 of Priestley’s great work on electricity. Beccaria says that all clouds, whether of thunder, rain, snow or hail, are formed by the electric fluid; that the electric matter is continually darting from the clouds in one place at the same time that it is discharged from the earth in another; and that the clouds serve as conductors to convey the electric fluid from those places of the earth which are overloaded with it to those which are exhausted of it. Having shown that the polarity of the magnetic needle is determined by the direction in which the electric current has passed through it, he suggests taking the polarity acquired by ferruginous bodies as a test for ascertaining the kind of electricity with which the thunder cloud is charged.

He also shows that the meteor called a falling star is an electrical appearance, explains the cause of the peculiar noise attending the electric spark, and states that the passage of electricity is not instantaneous through the best conductors. He found a spark to occupy at least half a second in passing through 500 feet of wire, and six and a half seconds through a hempen cord of the same length, although when the cord was dampened it passed through it in two or three seconds.

He was the first to show the electric spark while in its passage through water, and he observed that the water sank in the tubes whenever a spark passed from one to the other as the air was repelled by the electric fluid. He found the effect of the electric spark upon water greater than the effect of common fire on gunpowder, and says he does not doubt that, if a method could be found of managing them equally well, a cannon charged with water would be more effective (“dreadful”) than one charged with gunpowder.

He demonstrates that air, contiguous to an electrified body, gradually acquires the same electricity; that the electricity of the body is diminished by that of the air; that there is mutual repulsion between air and the electric fluid, and that the latter, in passing through any portion of air, creates a temporary vacuum.

The production of what he calls his new inventive phosphorus and the method he employs for revivifying metals, are described, respectively, at pp. 365 and 282 of his “Lettere dell’ elettricismo.”

REFERENCES.--Beccaria, “Lettere,” etc., Bologna, 1758, pp. 146, etc., 193, 266, 268, 290, 310, 345; likewise his “Elettricismo Artificiale,” Turin, 1753, pp. 110, 114, 227; Phil. Trans. for 1760, Vol. LI. p. 514; 1762, p. 486; 1766, Vol. LVI. p. 105; 1767, Vol. LVII. p. 297; 1770, Vol. LX. p. 277; 1771, p. 212, also Hutton’s abridgments, Vol. XI. p. 435; Vol. XII, pp. 291, 445; Vol. XIII. p. 50; Wartmann, “Mém. sur les Etoiles filantes”; Humboldt, “Relation historique,” Tome I; Lardner, “Lectures,” Vol. I. pp. 429–444; Sturgeon’s Annals, Vol. VI. pp. 415–420, 425–431, and Vol. VIII. p. 180; Noad, “Manual,” London, 1859, p. 197; Louis Cotte, “Observation ...” Paris, 1769 and 1772; “Mém. de Paris” for the same years and Jour. de Phys. for 1783; Ant. Maria Vassalli-Eandi, “Notizia sopra la vita ... di Beccaria,” 1816; Carlo Barletti, “Nuove Sperienze ...” Milano, 1771; “Biog. Générale,” Vol. V. pp. 77–78; “The Electrical Researches of Hon. Henry Cavendish,” Cambridge, 1879, No. 136; Hale, “Franklin in France,” Boston, 1888, Part I. p. 447; Humboldt, “Cosmos,” London, 1859, Vol. I. pp. 113–136, 202, 337; Vol. V. pp. 217–219, for the observations of Beccaria, Rozier, Kepler, Benzenberg, Brandes, Bogulawski, Nicholson, Arago and others on atmospheric electricity, aerolites, etc. See likewise Beccaria’s letters to Jean Claude Fromond, the Italian physicist (1703–1795), relating his experiments tending to prove that electric motions do not occur in vacuo, also his letters to the Princess Giuseppina di Carignano on the electricity of the moon, as well as to Jean Baptiste Le Roy and to Jacopo Bartolommeo Beccari relative to experiments with his kite; “Scelta di Opuscoli,” of Amoretti, Campi, Fromond and Soave, Vols. XIX. XXI. XXXII.; “Opuscoli Scelti,” II. 378; III. 243, 284, 377; V. 19.

=A.D. 1753.=--Bazin (Gilles Augustin), French physician and naturalist, publishes, at Strasbourg, an illustrated treatise on Magnetic Currents (“Description des Courants Magnétiques,” etc.), which also contains his observations upon the magnet, and a supplement to which appears during the year 1754.

REFERENCES.--“La Grande Encyclopédie,” Vol. V. p. 974; Michaud, “Biog. Univ.,” Vol. III. p. 353; Ninth “Britannica,” Vol. XV. p. 242.

=A.D. 1753.=--C. M., i. e. Charles Morrison and not Charles Marshall, of Greenock, Scotland, writes, from Renfrew, February 1, 1753, to the Scots’ Magazine, a letter entitled “An Expeditious Method of Conveying Intelligence,” wherein is first suggested a practical manner of transmitting messages by frictional electricity.

A full copy of this letter appears at pp. 7–9 of Robert Sabine’s “Electric Telegraph,” London, 1872, and at p. 9, 103, No. 570, of the Scientific American Supplement for December 4, 1886, the last-named also reproducing some correspondence establishing the identity of Charles Morrison which was found in the papers of Sir David Brewster.

In the article of Auguste Guérout, which appeared in La Lumière Electrique early in 1883, C. M. is alluded to as Charles Marshall. This is likewise the case in Johnson’s Encyclopædia, 1878, Vol. IV. p. 757. Fahie gives (“History of the Electric Telegraph,” London, 1884, pp. 68–77) a full account of the many inquiries instituted to establish the identity of C. M., which he admits to stand for Charles Morrison, although, at p. 81 of the same work, is given a letter of Sir Francis Ronalds alluding to Charles Marshall, of Renfrew. An article in Cornhill Magazine, Vol. II for 1860, pp. 65–66, speaks of an elderly Scotch lady who remembered a very clever man named Charles Marshall, who could make “lichtnin’ write an’ speak” and who could “licht a room wi’ coal-reek” (coal-smoke).

In his remarks upon the afore-named letter, made during the year 1859, Sir David Brewster says: “Here we have an electric telegraph upward of a hundred years old, which at the present day would convey intelligence expeditiously, and we are constrained to admit that C. M. was the inventor of the electric telegraph.... Everything done since is only improvement.”

REFERENCES.--Scots’ Magaz., XV. p. 73; “Le Cosmos,” Paris, Feb. 17, 1854; “Dict. of Nat. Biog.,” Vol. XXXIX. p. 107; Athenæum of Nov. 5, 1864; Lesage, at A.D. 1774; Th. Du Moncel, “Exposé des applications de l’électricité,” Paris, 1874, Vol. III. pp. 1 and 2.

=A.D. 1754.=--Diwish (Prokop), Diviss--Divisch (Procopius), a monk of Seuftenberg, Bohemia (1696–1765), erects, June 15, 1754, a lightning protector upon the palace of the curator of Prenditz, Moravia. The apparatus was composed of a pole surmounted by an iron rod supporting twelve curved up branches and terminating in the same number of metallic boxes filled with iron ore and closed by a boxwood cover traversed by twenty-seven sharp iron points which plunged at their base in the ore. All the system of wires was united to the earth by a large chain. The enemies of Diwish, jealous of his success at the court of Vienna, excited the peasants of the locality against him, and, under the pretext that his lightning rod was the cause of the great drought, they made him take down the lightning rod which he had utilized for six years and then imprisoned him. What is most curious is the form of this first lightning rod, which is of multiple points, like the one M. Melseu afterward invented.

REFERENCES.--Poggendorff, Vol. I. p. 580, for Procopius Divisch’s “Erfand einen Wetter Ableiter”; Scientific American, Sept. 10, 1887, p. 160; “Kronika Prace,” by Pokorny, of Prague; “Historical Magazine,” Feb. 1868, Art. XII. p. 93; “Prague News,” for 1754, art. of Dr. Scrinci.

=A.D. 1754.=--Ammersin (Rev. Father Windelinus), of Lucerne, Switzerland, announces in his “Brevis relatio de electricitate,” etc., that wood properly dried till it becomes very brown is a nonconductor of electricity. We have already mentioned the observation made by Benjamin Wilson (A.D. 1746) that, when a dry, warm piece of wood is broken across, one of the pieces becomes vitreously and the other resinously electrified.

Ammersin advises boiling the dried wood in linseed oil or covering it with varnish to prevent the possible return of moisture, and he states that wood thus treated seems to afford stronger appearances of electricity than does even glass (Phil. Trans., Vol. LII. part i. p. 342).

REFERENCES.--Ammersin, “Kurze Nachricht,” etc., pub. at Basel, 1771, and translated the same year by Jallabert, who embodied it in his “Versuche über die Elektricität,” etc.

=A.D. 1754.=--In his “Dissertations sur l’incompatibilité de l’attraction,” etc., Le Père Gerdil, Professor of Philosophy in the Royal University of Turin, speaks of agencies of which we shall never know anything and of others with which we shall inductively become acquainted, although we shall always ignore many of their respective quantities, qualities and differences. He says that the electric fluid explains the sympathy known to exist between amber and straws--shown by the analogy observed between electricity and magnetism to be the same as that existing between iron and the loadstone.

=A.D. 1754.=--Mr. Strype produces the sixth and last edition of the original “Survey of London” by John Stow, which first appeared during the year 1598.

In his account of Cornehill Ward, allusion is made to the “fair new steeple” of the Church of Saint Michael th’ Archangel, “begun to be built in the year 1421,” and, at p. 74, occurs the following: “As I have oft heard my father report, upon St. James’ night, certain men in the loft next under the bells, ringing of a peal, a tempest of lightning and thunder did arise, an ugly shapen sight appeared to them, coming in at the South window and lighted on the North, for fear whereof they all fell down and lay as dead for the time, letting the bells ring and cease of their own accord; when the ringers came to themselves, they found certain stones of the North window to be razed and scratched, as if they had been so much butter, printed with a lion’s claw; the same stones were fastened there again and so remain to this day.”

In one of the notes to William T. Thoms’ reprint of the above-named “now perfectly invalyable” work, he says: “It is quite clear from the tone in which Stow speaks of this ‘ugly shapen sight’ and the marks ‘printed with a lion’s claw,’ that he suspected this instance of the power of the electric fluid to be nothing less than a visitation from the foul fiend himself.”

Speaking of St. Paul’s Cathedral, Stow tells us that its pulpit cross “was by tempest of lightning and thunder defaced,” and that “on Wednesday, the fourth of June (in the year 1561), betweene three, four and five of the clock, in the after-noone, the steeple of Paule’s in London, being fired by lightning brast forth (as it seemed to the beholders) two or three yards beneath the foote of the crosse, and from thence burnt downe the speere to the stone worke and bels, so terribly, that within the space of foure houres, the same steeple with the roofes of the church ... were consumed.” Very curious and interesting reading will be found in the “Burnynge of Paule Church, London, in 1561, and the iiii day of June, by lyghtnynge at three of the clocke ...” by Wyllyam Seres, London, 1563; as well as in his previous work on like subject, published in 1561. See Report in “Archæologia,” London, 1794, Vol. XI. pp. 72–86; likewise the entry at A.D. 1769, relative to another lightning stroke in 1772.

Stow is perhaps best known by his “Annales, or a Generalle Chronicle of England.” In that portion of the latter work devoted to “the life and raigne of Queene Elizabeth” he states (London ed., 1631, p. 809) “that the knowledge and use of the sea compasse or needle was neither familiar nor understood but few yeeres before” the time of the navigators John Hawkins, Francis Drake, Martin Frobisher and Thomas Candish, and he adds (at p. 810) “that the honour of that invention, as touching the propertie of the Magneticall needle in pointing towards the Poles is attributed by (Flavius) Blondus in his Italia Illustrata (in the description of Campadia Felix) and by the great writer Paulus Jovius in lib. xxv. of his History in the end [sic], to the citizens of Amalfi.... The author’s name is no more particularly recorded, then [sic] to be one Flavio ... for to him that honour is given by Francis Lopez, of Gomara, in his West Indian History, lib. i. cap. 9, and by Peter Ciezius, in lib. ii. cap. 9, of his Indian Story, and by Pandulph: Collenutius in his History of Naples, who, three hundred yeeres since, namely in the yeere of our Saviour 1305, discovered that propertie in the Magnes and applied it to navigation” (see, for Flavius Blondus: George Hakewill, “An apologie,” etc., Oxford, 1635, lib. iii. s. 4, and lib. v. p. 60; “Blondi Flavii Fortiriensis ... Italia Illustrata,” 1531, folio; Flavius Blondus (Flavio Biondo), “Roma Ristaurata et Italia Illustrata,” Vinezia, 1558, 12mo; Niceron, “Mémoires ... des hommes illustres,” Paris, 1731, Vol. XVI. pp. 274–281).

A contemporary of Flavius Blondus, by name Michael Angelus Blondus (1497–1560), author of “De Ventis et Navigatione,” published at Venice in 1546, likewise alludes to the polarity of the needle, and gives a curious illustration of a mariner’s compass at Chap. XXIV. p. 15, of the last-named work. (For M. A. Blondus, see “La Grande Encyclopédie,” Vol. VI. p. 899.)

Stow makes reference (p. 810) to Dr. Gilbert’s De Magnete, to the “diuision of the plot or playne of the compasse into the thirty-two points,” considered by “Goropius in his lib. iii. De Origin. Hispanicis, to have been the inuention of some Germane,” and to the manner and “meanes saylers vsed to sayle, before they atteined the knowledge of the compasse.”

=A.D. 1755.=--Eeles--Eales (Henry), a prominent scientist of Lismore, Ireland, communicates to the Royal Society, on the 25th of April, 1755, a paper concerning the electrical property of steam and exhalations of all kinds. Eeles’ theory of the electricity of vapour (“On Vesicles and Atmospheres of Electricity”), afterward developed by Sir John Herschel, is fully explained in the “Encycl. Brit.” article on “Meteorology” (par. 135, etc.), and is also alluded to at p. 43 of Harris’ “Electricity” as well as at p. 153, Vol. XLIX. part i. of the Philosophical Transactions.

Mr. Eeles showed, that while the Leyden jar is being charged, both the inside and the outside have the same kind of electricity and that the negative electricity does not appear until the machine has ceased turning. Eeles’ hypothesis, extracted from his “Philosophical Essays,” and from the analysis of a course of lectures delivered at Trinity College, Cambridge, by Mr. Atwood, is treated of at length by George Adams in the fourth chapter of his “Essay on Electricity,” wherein pertinent allusion is also made to the fact of Mr. Eeles having been purposely shut out of Priestley’s “History and Present State of Electricity.”

REFERENCES.--Philosophical Transactions, Vol. XLVII. p. 524; Phil. Mag. and Journal, Vol. XLIV. p. 401 (1814).

=A.D. 1756.=--Le Chevalier Jacques C. F. de la Perriere de Roiffé (not Reiffé) is the author of “Méchanismes de l’Electricité et de l’Univers,” published at Paris, wherein he pretends to account for all electrical phenomena.

At p. 12 of his Préface, he curiously states that as everybody comprehends the distinction between elastic and non-elastic bodies, likewise the existence, nature and diversity of the properties of atmospheric fluids, with which all bodies are impregnated and by which they are surrounded, also the various expansive modes of activity to which they are subject, as well as their immiscibility as regards the surrounding air, without which latter they could not, however, subsist, he will in his new theory apply these principles to the mechanisms of electricity and of the universe as affected by the general laws and the invariable results attaching to shock and motion.

=A.D. 1756.=--In the “Subtil Medium Proved,” etc., of Mr. R. Lovett, lay-clerk of the cathedral church at Worcester, England, are shown numerous medical cures successfully made by electricity. He asserts that the electric fluid is almost a specific in all cases of violent pains, like obstinate headache, the toothache, sciatica, etc., but that it has not succeeded so well in rheumatic affections. He states that electricity properly administered has never caused injury, and he alludes to equally successful cures made by the Rev. John Wesley and by Dr. Wetzel, of Upsal.

The well-known physician, Antonius de Haen, during several years’ experience, made many cures of paralysis, St. Vitus’ dance, etc., by the agency of electricity, as related in his Ratio Medendi, Vol. I. pp. 199, 200, 233, 234 and 389. Allusion has been made in these pages to the employment of electricity for medical purposes by Kratzenstein (A.D. 1745) and by Jallabert (A.D. 1749), and Priestley named many others who have likewise used it successfully in their practice.

REFERENCES.--“Subtil Medium Proved,” etc., pp. 76, 101 and 112; also his “Philosophical Essays,” Worcester, 1761 and 1766, and his “Electrical Philosopher,” 1774; Wesley’s “Desideratum, or Electricity made Plain and Useful,” p. 3; Joseph Veratti, “Observations ... pour guérir les paralytiques....” La Haye, 1750.

=A.D. 1757.=--Dr. Darwin, of Lichfield, addresses to the Royal Society of London a paper which is read May 5, 1757, and in which he gives an account of experiments to prove that the electric atmosphere does not displace air, and that all light, dry, animal and vegetable substances, in particular, are slow to part with the electricity with which they have been charged (Phil. Trans., Vol. L. part i. pp. 252 and 351).

=A.D. 1757.=--Euler (Leonard), a native of Switzerland, who studied under the Bernoullis, and who succeeded Daniel Bernoulli as Professor of Mathematics at St. Petersburg, was undoubtedly one of the greatest analysts the world has ever produced (“Encycl. Brit.,” Fifth Dissertation of the eighth edition, Vol. I. p. 742).

He adopted the theory of Descartes that the magnetic fluid moves from the equator to the poles, and he endeavoured to determine mathematically the course of the magnetic needle over the earth’s surface. He announces that “the magnetic direction on the earth follows always the small circle which passes through the given place and the two magnetic poles of the earth,” or, as worded by Sir David Brewster, that “the horizontal needle is a tangent to the circle passing through the place of observation and through the two points on the earth’s surface where the dipping needle becomes vertical or the horizontal needle loses its directive power.”

He entertained very peculiar ideas regarding the source of power in the loadstone, the pores of which he imagined were filled with valves admitting of the entrance of the current and preventing its return. His notions on this subject are best given in his own words: “Non-magnetic bodies are freely pervaded by the magnetic matter in all directions; loadstones were pervaded by it in one direction only ... water, we know, contains in its pores particles of air ... air, again, it is equally certain, contains in its pores a fluid incomparably more subtile, viz. æther, and which, on many occasions, is separated from it, as in Electricity; and now we see a still further progression, and that ether contains a matter much more subtile than itself--the magnetic matter which may, perhaps, contain in its turn others still more subtile.... The loadstone, besides a great many pores filled with ether, like all other bodies, contains some still much more narrow into which the magnetic matter alone can find admission. These pores are disposed in such a manner as to have communication with each other, and constitute tubes or canals through which the magnetic matter passes from the one extremity to the other. Finally, this matter can be transmitted through these tubes only in one direction, without the possibility of returning in the opposite direction.... As we see nothing that impels the iron toward the loadstone, we say that the latter attracts it. It cannot be doubted, however, that there is a very subtile, though invisible matter, which produces this effect by actually impelling the iron towards the loadstone.”

REFERENCES.--“Journal des Savants” for March and April 1868; Euler’s “Letters,” translated into English, 1802, Vol. I. p. 214, and Vol. II. pp. 240, 242, 244; “Berlin Memoirs,” for 1746, p. 117; 1757, p. 175; 1766, p. 213; Poggendorff, Vol. I. p. 702; “Nova Act. Petropol.” for 1779, Vol. III; “Pièces de Prix de l’Acad. des Sc. de Paris,” Vol. V. Mém. II and IX, this last-named publication, containing likewise a joint Memoir of D. Euler, J. Bernoulli and E. F. Dutour upon the mariner’s compass, which appeared in Paris during 1748; Whewell, “History of the Inductive Sciences,” 1859, Vol. I. pp. 225, 367, 370; Vol. II. pp. 32, 40.

His son, Albert Euler, censured Halley’s magnetical hypothesis, and proposed, in 1766, a theory requiring the assumption of only two poles, distinct, however, from those of the terrestrial axis.

=A.D. 1757.=--Dollond (John), who was at first a silk weaver at Spitalfields, England, which occupation he abandoned in order to give his exclusive attention to scientific experimental studies, discovered the laws of the dispersion of light and constructed the first achromatic telescope as well as several improved instruments for magnetic observations. A full description of the most important of these, accompanied by illustrations, can be found in the articles of the “Encyclopædia Britannica” on magnetic instruments.

REFERENCES.--Kelly’s “Life of John Dollond,” London, 1808; Phil. Mag., Vol. XVIII. p. 47; Thomas Thomson, “Hist. of Roy. Soc.,” London, 1812, pp. 379–382; “Directions for using the Electric Machine made by P. and J. Dollond,” London, 1761.

=A.D. 1757.=--Wilcke (Johann Karl), a very distinguished scientist of Stockholm (1732–1796), introduces new phenomena respecting the production of electricity produced by melting electrical substances, which he discovers in continuation of experiments begun by Stephen Grey. He gives the name of spontaneous to the electricity produced by the liquefaction of electrics, observing that the electricity of melted sulphur does not appear until it commences to cool and to contract, its maximum being reached at its point of greatest contraction. Melted sealing wax, he says, becomes negatively electrified when poured into glass, but, when poured into sulphur, it is positively electrified, leaving the sulphur negative (Sir Humphry Davy, “Bakerian Lectures,” London, 1840, p. 36 and notes).

While in Berlin, he and Æpinus investigate the subject of electric atmospheres, and they are led to the discovery that plates of air can be charged in the same manner as plates of glass. (See Canton, A.D. 1753.) This they did by suspending large wooden boards, which were covered with tin and whose flat surfaces were held parallel to and near each other. They found that upon electrifying one of the boards positively the other was always negative, and that with them could be given shocks like those produced by a Leyden jar. They likened the state of the boards to the condition of the clouds and the earth during a thunderstorm, the earth being in one state and the clouds in the opposite, the body of air between them answering the same purpose as the small plate of air between the boards or the plate of glass between the two metallic coatings of the Leyden jar.

In Wilcke’s treatise, alluded to below, he defines the two electricities much more clearly than had previously been done. He distinguishes three causes of excitation, viz. warming, liquefaction and friction; the spontaneous electricity already alluded to, he further says, is the result of the apposition or mutual action of two bodies, in consequence of which one of them is electrified positively and the other negatively; communicated electricity, on the other hand, is that which is superinduced upon the whole or part of a body, electric or non-electric, without the body having been previously heated, melted or rubbed, or without any mutual action between it and any other body. This distinction is, in general, very obvious, but Mr. Wilcke defines it throughout his work in a very clear manner, citing cases wherein they are frequently confounded.

Wilcke and Anton Brugmans (A.D. 1778) first propounded the theory of two magnetic fluids, which was afterward established by Coulomb (A.D. 1785) and perfected by the great mathematician Poisson (A.D. 1811). The hypothesis of the two fluids supposes that a magnet contains minute invisible particles of iron, each of which possesses by itself the properties of a separate magnet. It is assumed that there are two distinct fluids--the austral and the boreal--which reside in each particle of iron. These fluids are inert and neutral when combined, as in ordinary iron, but when they are decomposed the particles of the austral attract those of the boreal, and vice versa, while they each repel one another.

REFERENCES.--Wilcke, “Disputatio inauguralis physica,” etc., published Rostock, 1757, also his “Herrn Franklin’s briefe von der electricitat,” etc., Leipzig, 1758, his “Jal om Magneten,” 1764, and his “Über den Magneten,” Leipzig, 1758; besides 1794–1795; likewise his different Memoirs in the “Swedisches Musæum,” Vol. I. p. 31, and in both the “Schwedischen Akad. Abhandlungen,” etc. (also Neue Abhand.) and the “Vetensk Acad. Handl.” for 1758, 1759, 1761–1763, 1766–1770, 1772, 1775, 1777, 1780, 1782, 1785, 1786, 1790; “The Electrical Researches of Hon. Hy. Cavendish,” 1879, No. 134.

=A.D. 1759.=--Hartmann (Johann Friedrich), of Hanover, is the author of three works on electricity, published in that city during 1759, 1764 and 1766, wherein he gives an account of several very curious electrical experiments. One of the most interesting of these demonstrates the progressive motion of the electrical discharge. When he passes the shock through many small cannon balls, sometimes to the number of forty, placed upon small drinking goblets close by one another, all the sparks are seen and all the cracklings are heard at the same moment; but when he substitutes eggs (preferably ten or twelve) for the balls, the progress of the explosion is visible, every two giving a flash and a report separately.

He remarks that upon one occasion, as he re-entered a room which he had just before left, after making therein a number of experiments, he observed a small flame following him as he walked about swiftly while holding a lighted candle in his hand. The flame vanished whenever he stopped to examine it, and he attributed its appearance to the presence of sulphur thrown into the air by continued violent electrification.

REFERENCES.--Hartmann, “Abhandlung von der verwandschaft,” etc., Hanover, 1759, pp. 58, etc., and 135; also his “Electrische experimente,” etc., Hanover, 1766, and his “Anmerkungen,” etc., 1764, 4to, p. 38; Friedrich Saxtorph, “Elektricitätsläre,” Vol. II; Hamburgisches Magazin (also Neues Hamb. Mag.) for 1759, Vol. XXIV, and for 1761, Vol. XXV; “Nov. Acta Acad. Nat. Curios,” Vol. IV. ss. 76–82, 126; “Göttingischen gemein. Abhand.,” von Jahr 1775.

=A.D. 1759.=--Wesley (John), the founder of Methodism (1703–1791) and the most eminent member of a very distinguished English family, publishes “The Desideratum; or Electricity made Plain and Useful, by a Lover of Mankind and of Common-sense.” In this, he relates at great length the cures of numerous physical and moral ailments, attributed to the employment of the electric fluid, under such curious headings as “Electricity, the Soul of the Universe,” “Electricity, the Greatest of all Remedies,” etc. (“The Library of Literary Criticism,” C. W. Moulton, Buffalo, 1901–1902, Vol. IV. pp. 110–129).

=A.D. 1759.=--Æpinus (Franz Maria Ulrich Theodor) (1724–1802), celebrated German natural philosopher, member of the Scientific Academies of Berlin and St. Petersburg, publishes in the latter city his most important work, “Tentamen Theoriæ Electricitatis et Magnetismi,” wherein he adopts, as did Wilcke, all the general principles of Franklin’s theory of positive and negative electricities. Therein he also shows that the phenomena of electricity depend mainly upon the tendency of the fluid to attain a state of equilibrium by passing from bodies containing an excess to others which have less than the natural quantity; that the electric fluid existing in the pores of all bodies moves without obstruction in non-electrics and with much difficulty in electrics; that all bodies contain a fluid whose particles mutually repel one another with forces decreasing as the distance between them increases, and, according to the same law, attract the particles of the bodies with which they are in combination.

It has already been shown that, in conjunction with Wilcke, he found the means of charging a plate of air. This experiment, suggested by some of the observations made by Canton and Franklin, led to what may be considered one of the greatest discoveries in the science of electricity, for in this was first demonstrated the grand principle of induction (see Grey at A.D. 1720), and the result led to Volta’s discovery of the electrophorus. Volta, also, was the first to apply to an electrometer the apparatus invented by Æpinus for condensing electricity.

Æpinus first discovers to its fullest the affinity existing between electricity and magnetism, explaining nearly all the phenomena of magnetism (“De Similitudine vis electricæ et magneticæ”; “Similitudinis effectuum vis magnet. et. elect.: novum specimen” in the “Novi Comment. Acad. Petrop.,” Vol. X. p. 296). He improves upon the methods employed by both Duhamel and Michell for the construction of artificial magnets in a different line from that employed by John Canton, A.D. 1753. He lays the bar to be magnetized upon the ends of the opposite poles of two powerful field magnets, and places two bunches of magnetic bars upon the middle of the bar, separating the bunches by a piece of wood and keeping together the poles of each of the same name as that of the powerful fixed magnet nearest to it. These two bunches are then held at an inclination of 15 to 20 degrees, and are drawn away from each other to the end of the bar which is to be magnetized, so that each half of the bar receives the same number of strokes. When the bar is very thick, the process should be repeated upon its reverse, and in order to make the result more effective, the united ends of the bars should at the outset be ground together, and pressure should be applied while the operation is going on.

Æpinus was the first to discover the polarity of the tourmaline. After M. Lechman acquainted him with its attractive power, he made many experiments, of which he communicated the very important results, during the year 1756, to the Academy of Sciences and Belles-Lettres at Berlin. Up to this time but little was known regarding the necessity of heat to excite the tourmaline. Æpinus found that he could electrify it to a high degree by placing the stone in boiling water, and that it was necessary to heat it to between 99½ degrees and 212 degrees Fahrenheit to develop its attractive powers. One of the extremities of the tourmaline terminated by the six-sided pyramid then becomes charged with positive electricity, while the other extremity is negative. When the stone is of considerable size, flashes of light can be seen along its surface.

M. De Romé Delisle, in his “Essai de Cristallographie,” Paris, 1772, p. 268, alludes to what has already been stated relative to the necessity of heating the tourmaline (see J. G. S. at A.D. 1707, and Leméry at A.D. 1717), and he gives an extract from the work attributed to Adanson, as mentioned at A.D. 1751. Delisle’s references embrace: “Act. Paris,” 1717, p. 9; “Act. Berolin,” 1756, p. 105; “Lettre du Duc de Noya Caraffa à M. de Buffon,” Paris, 1759; Ascendrecker, Aschentrecher, Aschenzicher (tire-cendre), “Trip: Tourmaline, Vog. min.” 191; “Act. Holmens,” 1768, p. 7; besides, at pp. 209, 233 and 245 he speaks of the electrical and phosphorescent properties of crystals, showing that the lapis lyncurius of the ancients is the hyacinth or zircon of to-day (see B.C. 321), and not, as many believe, either amber or belemnite (pierre de foudre, lapis fulminaris), while the hyacinth of old was a purple stone which, if now found, would be classed among the amethysts.

REFERENCES.--“Allgemeine Deutsche Biographie,” Leipzig, 1875, Vol. I. p. 129; Æpinus, “Sermo Acad. de similitudine,” etc., 1758, and his “Recueil ... sur la tourmaline,” 1762; “Novi. Com. Petropol.,” for 1761, 1764, 1768; “Acta Acad. Moguntinæ,” Vol. II. p. 255; Leithead, “Electricity,” p. 289; Phil. Trans., Vol. LI. p. 394, and Vol. LVII. part i. p. 315; “Encycl. Brit.,” articles “Electricity” and “Magnetism”; Bigeon’s report in the “Annales de Ch. et de Phys.,” 2^e série, Tome XXXVIII. p. 150; Van Swinden, “Recueil,” etc., La Haye, 1784, Vols. I and II passim; Becquerel in Annales de Chimie et de Physique, Vol. XXXVI. p. 50; Thomson, “Hist. Roy. Soc.,” 1812, p. 184; “The Electrical Researches of the Hon. Henry Cavendish,” Cambridge, 1879, Nos. 1, 134, 340 and 549; Lord Kelvin (Sir Wm. Thomson), “Æpinus atomized,” in Phil. Mag. for March 1902, p. 257, etc., and in Journal de Physique for Sept. 1902, p. 605.

=A.D. 1759.=--Symmer (Robert) assails the theory announced by Dufay (see Franklin, A.D. 1752), and shows, in a paper submitted to the Royal Society, December 20, 1759, that all the electrical phenomena are produced by two distinct but coexistent fluids not independent of, but counteracting each other. He says that equal quantities of these fluids are contained in all bodies while in their natural condition; that when a body is positively electrified it does not hold a larger share of electric matter, but a larger portion of one of the active powers, and when negatively electrified a larger portion of the other, and not, as Franklin’s theory supposes, an actual deficiency of electric matter. Symmer’s theory is perhaps best explained in his own words, as follows: “It is my opinion that there are two electric fluids (or emanations of two distinct electric powers), essentially different from each other; that electricity does not consist in the efflux and afflux of these fluids, but in the accumulation of the one or the other in the body electrified; or, in other words, it consists in the possession of a larger portion of the one or of the other power than is requisite to maintain an even balance within the body, and lastly, that according as the one or the other power prevails, the body is electrified in one or the other manner.”

Very curious reading may be had by reference to the volumes of the Philosophical Transactions named below, in which Symmer details many experiments with pieces of silk, as well as with white and coloured, new and newly cleansed silk and worsted stockings. Therein he shows his ability to charge the Leyden jar with either positive or negative electricity, according as he presents a black or white stocking to the wire of the phial. These experiments, which Symmer admits to have made for the express purpose of proving the existence of two electricities, further illustrate the phenomenon of electrical cohesion, although the latter is still better demonstrated by means of panes of ordinary glass. He thus expresses himself: “Upon these considerations, we may expect, from the experiment in hand, the means of determining whether the distinction of electricity into two different kinds is merely nominal, or if there is an essential difference between them; for, after the glass plates have been electrified in one position, so as to be incapable of receiving any more electricity, if they be inverted, and in that new position presented to the chain and wire, and the globe again be put in motion, according as one or other of those opinions hold, corresponding effects will follow.”

Symmer also proves his two distinct powers of electricity by the experiment of passing the electric shock through a quire of paper instead of through a single card (“Lib. Useful Knowledge,” London, 1829, “Electricity,” p. 44).

REFERENCES.--“Electricity in the Service of Man,” R. Wormell, London, 1900, p. xiv; Philosophical Transactions, Vol. LI. part i. pp. 171, 340, 366, 373, etc., 389, and Vol. LVII. p. 458; also Hutton’s abridgments, Vol. XI. p. 405; Nollet, “Lettres,” etc., Vol. III. p. 42; “Encycl. Brit.,” article “Electricity”; “Library of Useful Knowledge,” London, 1829, “Electricity,” Nos. 160 and 161.

=A.D. 1760.=--Mayer (Johann Tobias, Sen.) (1723–1762), one of the most celebrated German astronomers, director of the observatory at Göttingen, is the first to make known the law of the inverse square resulting from actual experimental investigation. This he does in a paper, “Inclination and Declination of the Magnetic Needle, as deduced from theory,” read before the Royal Society at Göttingen, wherein he states that the intensities of the magnetic attractions and repulsions vary inversely as the squares of the distances from the pole of a magnet. Consult “Magnetism,” in the ninth edition of the “Encyclopædia Britannica,” for additional reference to the above paper, also section 14 of the same work for an account of Mayer’s dipping needle as constructed by General Sabine.

REFERENCES.--Delambre’s notice of the life of J. T. Mayer in the “Biographie Universelle”; Hutton’s “Mathem. Dict.”; Montucla, “Histoire des Mathématiques”; list of his works added to the éloge pronounced by Kaestner, Göttingen, 1762; “Abhandlungen von Galvani und andern,” Prague, 1793; Whewell, “History of the Inductive Sciences,” 1859, Vol. II. pp. 206, 221; Coulomb, “Mémoires Acad. Paris” for 1786 and 1787; “Royal Soc. Cat. of Sc. Papers,” Vol. IV. pp. 311–314; Lambert, “Reports of the Berlin Academy” for 1776.

Mayer (Johann Tobias, Jr.), 1752–1830, is the author of Memoirs on the magnetic needle as well as upon many electrical experiments, of which details may be found in the Journal der Physik of Friedrich A. C. Gren and in the “Comment Soc. Göttingen recent.”

=A.D. 1760.=--Delaval (E. H.) communicates between 1760 and 1764 several papers to the London Royal Society in reference to experiments made for the purpose of ascertaining the conducting powers of a body in different states. Therein, he shows that animal and vegetable substances lose their conducting powers when reduced to ashes, and that while metals are the best conductors, their oxides are non-conductors. His experiments made with island (Iceland) crystal (well known for its extraordinary property of double refraction), proved that it is affected by heat differently from other substances named, since the temperature necessary to render them electric makes the crystal non-electric. He had a piece of crystal of which, he said, one part became non-electric when greatly heated, while the other part, with the same or even a much greater heat, remained perfectly electric. These experiments did not, however, succeed with Sir Torbern Bergman, who repeated them with great care and who found that island crystal was a conductor in all cases, to whatever degree of heat it was exposed.

REFERENCES.--Phil. Trans., Vol. LI. part i. p. 83; Vol LII. part i. pp. 353, etc., and part ii. p. 459; also Vol. LIII. part i. pp. 84–98; and Hutton’s abridgments, Vol. XI. pp. 334, 589; Vol. XII. p. 140; Thomas Thomson, “Hist. of Roy. Soc.,” p. 443; Thos. Young, “Course of Lectures,” 1807, Vol. II. p. 679, for notes on Dr. Wm. H. Wollaston’s paper concerning the double refraction of Iceland crystal.

=A.D. 1760–1762.=--Bergman--Bergmann--(Torbern Olof), celebrated Swedish astronomer, naturalist and chemist, writes several letters to Mr. Wilson, which are read before the Royal Society, Nov. 20, 1760, and March 18, 1762, wherein he alludes to the possibility of electrifying plates of ice in the same manner as plates of glass. In a subsequent letter he details experiments with silk ribbons of different colours, almost as curious as those of which an account has already been given (by Symmer at A.D. 1759), and from which he concludes that there is a certain fixed order regarding positive and negative electricity in which all bodies may be placed while other circumstances remain unchanged.

REFERENCES.--Bergman’s “Bemerkung ... Isländischen Krystales,” “Comment ... electrica turmalini,” “Elektrische Versuche,” etc., and his other works referred to in the Philosophical Transactions, Vol. LI. p. 907; Vol. LIII. p. 97; Vol. LIV. p. 84; Vol. LVI. p. 236; also Hutton’s abridgments, Vol. XI. pp. 506, 705; Vol. XII. pp. 109, 343; “Nova Acta Soc. Upsal.,” “K. Schwedischen Akad. Abhand.,” “Aus dem Schwed. Magazine,” Phil. Mag., IX. p. 193; “Eng. Cycl.,” Vol. I. pp. 664–665; Gmelin’s “Chemistry,” Vol. I. p. 320; Thomas Thomson, “Hist. of the Royal Society,” London, 1812, pp. 444, 475–477.

=A.D. 1761.=--The many experiments made at this period by Ebenezer Kinnersley, of Philadelphia, relative to the two contrary electricities of glass and sulphur, are endorsed by his close friend Benjamin Franklin in his Letters at pp. 99, 100 and 102–105. He makes several curious observations on the elongation and fusion of fine iron wires whenever a strong charge is passed through them while in a state of tension, to which Dr. Watson makes special reference in a paper read before the Royal Society. He believes that lightning does not melt metal by a cold fusion, as Dr. Franklin and himself had formerly supposed, and that when it passes, for instance, through the blade of a sword, if the quantity is not very great, it may heat the point so as to melt it, while the broadest and the thickest part may not be sensibly warmer than before.

To ascertain the effects of electricity upon air, Kinnersley devised an instrument which he called an electrical air thermometer, and which is described at p. 626, Vol. VIII of the 1855 “Encyclopædia Britannica.” With this he could show the sudden rarefaction which air undergoes during the passage of the electric spark through it, heat being produced without accompaniment of any chemical change in the heated body.

Some other important observations made by Kinnersley, who, besides being an intimate friend, was the original associate of Ben. Franklin, are summed up as follows: A coated flask containing boiling water cannot be charged, the electricity passing off with the steam; but when the water gets cold the flask may be charged as usual. A person in a negative state of electricity standing upon an electric, and holding up a long sharp needle out of doors in the dark, observes light upon the point of it. No heat is produced by electrifying a thermometer, nor by passing shocks through large wire, but small wire is heated red-hot, expanded and melted (Phil. Trans. for 1763, Vol. LIII. p. 84; Thomson, “Hist. Roy. Soc.,” p. 445).

In the New York “Electrical Review” of May 13, 1905, will be found the following curious reference to the Boston Art Club exhibits of President R. H. W. Dwight:

“Among these is an interesting broadside, which gives a summary of two lectures on electricity by Ebenezer Kinnersley delivered in Faneuil Hall in September, 1751--the first lectures probably ever delivered on the then new subject of electricity. Kinnersley was an Englishman, who was head master in English literature in the College of Philadelphia, from 1753 to 1773, a student of science, who made a number of discoveries in electricity and invented a number of quaint electrical devices. He and Franklin were on intimate terms, and were closely associated in their electrical experiments. Kinnersley has been erroneously cited as an anticipator of Oersted’s discovery of the deflection of a magnetic needle by an electric current. The former’s experiment, however, was purely electrostatic. In the summary of these two lectures, among other things, it states that electricity ‘is an extremely subtile fluid; that it doth not take up any perceptible time in passing through large portions of space; that it is mixed with the substance of all other fluids and solids of our globe; that our bodies at all times contain enough of it to set a house on fire.’”

The exhibits of President Dwight are:

“An artificial spider animated by the electric fire so as to act like a live one; a shower of sand which rises again as fast as it falls; a leaf of the most mighty of metals suspended in the air, as is said of Mahomet’s tomb; electrified money which scarce anybody will take when offered to them; a curious machine, acting by means of the electric fire, and playing a variety of tunes on eight musical bells.”

This broadside of 1751 appears to antedate any other similar notice of electrical experiments.

The “Electrical Review” of April 23, 1904, p. 621, had published copy of an advertisement from the Massachusetts Gazette of March 7, 1765, giving notice of a course of lectures by David Mason, illustrated by “entertaining experiments on electricity similar to those cited in the broadside under date of 1751.” The advertisement of 1765, here referred to, appears at A.D. 1771.

REFERENCES.--Sturgeon’s “Lectures,” London, 1842, p. 169; “The Electrical Researches of Hon. Henry Cavendish,” 1879, Nos. 125, 137, 213; Phil. Trans., Vol. LIII. part i. pp. 84–87; Vol. LIV. p. 208; Vol. LXIII, 1773, part i. p. 38; also the Hutton abridgments, Vol. XI. p. 702, and Vol. XIII. p. 370; Bertholon, “Elec. du Corps Humain,” 1786, Vol. I. pp. 23, 33, 214, 217, 220.

=A.D. 1762.=--Sulzer (Johann Georg), a Swiss philosopher, member of the Berlin Academy of Sciences, in his “Theory of Agreeable and Disagreeable Sensations” (“Theorie d. angenehmen u. unangenehmen Empfindungen,” Berlin, 1762), thus expresses himself: “When two pieces of metal, one of lead and the other of silver, are so joined together that their edges make one surface, a certain sensation will be produced on applying it to the tongue, which comes near to the taste of martial vitriol (vitriol of iron); whereas each piece by itself betrays not the slightest trace of that taste” (F. C. Bakewell, “Manual of Electricity” London, 1857, Chap. III. p. 28).

The passage in the edition “Nouvelle Théorie des Plaisirs,” published in 1767, is thus given by Sabine, “Electric Telegraph,” 1872, p. 15: “On taking two pieces of different metals--silver and zinc--and placing one of them above and the other underneath his tongue, he found that, so long as the metals did not make contact with each other, he felt nothing; but that when the edges were brought together over the tip of his tongue, the moment contact took place and during the time it lasted, he experienced an itching sensation and a taste resembling that of sulphate of iron....” Sulzer does not appear to have been much surprised at the result, thinking it “not improbable that, by the combination of the two metals, a solution of either of them may have taken place, in consequence of which the dissolved particles penetrate into the tongue; or we may conjecture that the combination of these metals occasions a trembling motion in the respective particles, which, exciting the nerves of the tongue, causes that peculiar sensation.”

And thus, remarks Pepper, a prominent fact has slept in obscurity from the time of Sulzer to the time of Galvani.

REFERENCES.--Izarn, “Manuel,” Paris, 1804, p. 4; Sturgeon, Annals, Vol. VIII. p. 363; also note at p. 491 of Ronalds’ “Catalogue”; Mém. de l’Acad. de Berlin, “Théorie Générale du Plaisir”; also “Temple du Bonheur,” published at Bouillon (Pays Bas), 1769, Tome III. p. 124, this last-named work being alluded to in the Journal des Débats, 7 Vendémiaire, au X; Edm. Hoppe, “Geschichte,” 1884, p. 128; C. H. Wilkinson, “Elements of Galvanism,” Vol. I. p. 69, note; Albert’s “Amer. Ann. d. Artz,” Vol. II. Bremen, 1802.

=A.D. 1762.=--Ledru Comus, French Professor of Natural Philosophy, invents a mode of telegraphing which is described and fully illustrated in Vol. I of Guyot’s “Nouvelles Récréations Physiques et Mathématiques,” Paris, 1769; as well as at p. 278 of “Mémoires, Correspondance et Ouvrages Inédits de Diderot,” Paris, 1821, in one of the letters to Mlle. Voland dated July 28, 1762.

His apparatus consisted of two dials, each bearing upon it twenty-five letters of the alphabet, which were moved by the agency of magnets and of magnetized needles; but Auguste Guérout considers the contrivance to have been merely a speculative one, as will be seen by his article, reproduced from “La Lumière Electrique” of March 3, 1883, in No. 384 of the “Scientific American Supplement.”

REFERENCES.--Journal de Physique for 1775, Vols. V and VI; for 1776, Vol. VII; and for 1778, Vol. I; “Scelta di Opuscoli,” Milano, 1776.

=A.D. 1765.=--Cigna (Giovanni Francesco), native of Mondovi, Italy, and nephew to the electrician Beccaria (A.D. 1753), became secretary to the society of savants who gave birth to the Royal Academy of Sciences at Turin, and whose Memoirs contain his work, “De novis quibusdam experimentis electricis,” 1765.

At pp. 31–65 of the above Memoirs is given a full account of Cigna’s many curious observations made with silk ribbons placed in various positions, and in contact with different surfaces, instead of with the silk stockings employed by Symmer (A.D. 1759). He thus supplies the main defect of Dufay’s theory (A.D. 1733) by proving that the two opposite electricities are produced simultaneously. On p. 47 of the same work will be found a report of Cigna’s experiment with ice to ascertain whether electric substances contain more electric matter than other bodies.

REFERENCES.--Vol. III. p. 168 of Nollet’s “Letters,” for an account of his observations upon the electric attraction and repulsion between conducting substances immersed in oil; as well as Chap. II. s. 3., vol. i. of Van Swinden’s “Receuil,” etc., published at La Haye, 1784. Should also be consulted: Cigna’s “Memoirs on Electricity and Magnetism” in the “Miscellanea ... Taurinensia,” and the several communications made by him to Priestley, Lagrange and others in 1775 concerning Volta’s electrophorus; likewise “Memorie istorische ... di Gianfrancesco Cigna de Antonmaria Vassalli Eandi,” Torino, 1821.

=A.D. 1766–1776.=--Lambert (Johann Heinrich), a profound German mathematician, native of Upper Alsace, publishes in Vol. XXII of the “Reports of the Berlin Academy” two beautiful Memoirs upon the “Laws of Magnetic Force” and upon the “Curvature of the Magnetic Current,” both of which, according to Dr. Robison, would have done credit to Newton himself.

In the first Memoir, says Harris, the author endeavours to determine two very important laws; one relating to the change of force as depending upon the obliquity of its application, the other as referred to the distance. In the second Memoir the curves of the magnetic current are investigated by the action of the directive or polar force of a magnet upon a small needle. Lambert concludes that the effect of each particle of the magnet on each particle of the needle, and reciprocally, is as the absolute force or magnetic intensity of the particles directly, and as the squares of the distances inversely.

Noad states (“Manual,” London, 1859, p. 580) that Lambert’s deductions were confirmed twenty years later by Coulomb, through the agency of his delicate torsion balance, and more recently (about the year 1817) by Prof. Hansteen, of Christiania.

Previous to the above-named date, in 1760, Lambert had published, both at Leipzig and at Augsburg, his “Photometria, sive de Mensura et Gradibus Luminis, Colorum et Umbræ,” the sequel to a tract printed two years before, wherein he indicates the mode of measuring the intensity of the light of various bodies. The celebrated mathematician and astronomer, Pierre Bouguer (1698–1758), who had published, in 1729, his “Essai d’Optique,” etc., which was greatly enlarged in his “Traité,” etc., brought out by La Caille in 1760, may be considered the founder of this branch of the science of optics, to which the name photometry has been given by English writers. The photometer designed by Sir Benjamin Thompson, Count Rumford (entered at A.D. 1802), has been described in Phil. Trans. for 1794, Vol. LXVII. His method is to cast two shadows of a given object near each other on the same surface, the lights being removed to such distances that the shadows appear equally dark.

REFERENCES.--Sir John Leslie’s “Fifth Dissertation” in the eighth “Encycl. Brit.”; Count Rumford’s photometer illustrated at Plate XXVII. figs. 387, 388, vol. i. of Dr. Thomas Young’s “Course of Lectures,” London, 1807; also Vol. II. pp. 282 and 351 of the same work, concerning photometry generally; Dredge and others, “Electric Illumination,” etc. (chiefly compiled from London Engineering), Vol. II. pp. 101–117; Brewster’s “Edin. Jour. of Sc.,” 1826, Vol. II. p. 321; Vol. III. p. 104; Vol. V. p. 139, for William Ritchie’s articles on the photometer of Mr. Leslie, and relative to an improved instrument upon the principles of Bouguer (Edin. Transactions, Vol. X. part. ii.); Lambert’s biography and the article “Magnetism” in the “Encycl. Brit.”; Harris, “Rudim. Magn.,” Part III. pp. 20, 33, 191–203.

It may be added that all the valuable manuscripts left by Lambert were purchased by the Berlin Academy, and were afterward published by John Bernoulli, a grandson of the celebrated John Bernoulli alluded to at A.D. 1700.

=A.D. 1766.=--Lullin (Amadeus), in his “Dissertatio physica de electricitate,” Geneva, 1766, at p. 26, alludes to Beccaria’s experiments, saying that he produced much greater effects with the electric spark by passing the latter through oil instead of water: oil being a much worse conductor, the spark in it is larger. At p. 38 of the same work he details the experiments made to prove the correctness of Mollet’s doctrine regarding the constant motion of electrical atmospheres, and at p. 42 are given his experiments to show the production of electricity in the clouds. With a long insulated pole projecting from the mountain side he observed, among other effects, that when small clouds of vapour produced by the sun’s heat touched only the end of the pole the latter was electrified, but that it was not affected if the entire pole was covered by the vapour (“Lib. Useful Knowledge,” “Electricity,” Chap. XI. Nos. 154, etc.).

Lullin, it is said, proposed a modification of Reusser’s plan of telegraphing, in manner stated at p. 69 of Reid’s 1887 “Telegraph in America.”

=A.D. 1766.=--L’Abbé Poncelet, a native of Verdun, France, publishes at Paris “La Nature dans la formation du Tonnerre,” etc., wherein he indicates a method of protecting from lightning residences, pavilions and other structures, by constructing them of resinous woods and lining them with either silk or waxed cloths. He quaintly remarks that as they thus present “on all sides resinous surfaces, which never receive phlogiston by communication, the latter (thunder and lightning), after having leaped lightly around the pavilion and finding itself unable to attack it, will probably depart in order to pursue its ravages elsewhere.”

REFERENCES.--Scientific American Supplement, No. 66, p. 1053, for a copy of the frontispiece of the above-named work; also Figuier, “Exposition et Histoire,” etc., 1857, Vol. IV. pp. 234, 235.

=A.D. 1767.=--Bozolus (Joseph), an Italian Jesuit, Professor of Natural Philosophy at Rome, is the first (and not Cavallo, A.D. 1775) to suggest employing the active principle of the Leyden jar for the transmission of intelligence.

His plan is to place underground two wires which are to be brought at each station close enough to admit of the passage of a spark. One of the wires is to be connected with the inner coating and the other with the outer surface of a Leyden phial; the sparks observed at the opening between the wires being there made to express any meaning according to a preconcerted code of signals.

REFERENCES.--Latin poem entitled “Mariani Parthenii Electricorum,” in six books, Roma, 1767, lib. i. p. 34 (describing the telegrafo elettrico scintillante); also Saturday Review, August 21, 1858, p. 190, and _Cornhill Magazine_ for 1860, Vol. II. p. 66.

=A.D. 1767.=--Priestley (Joseph), the earliest historian of electrical science, publishes, by advice of Benjamin Franklin, the first edition of his great work, “The History and Present State of Electricity,” of which there were four other separate enlarged issues, in 1769, 1775, 1775 and 1794. During the year 1766 he had been given the degree of Doctor of Laws by the Edinburgh University and he had also, at the instance of Franklin, Watson and others, been made a member of the English Royal Society, which, a few years later, bestowed upon him the Copley medal.

Speaking of the above-named work, Dr. Lardner says (“Lectures, 1859, Vol. I. p. 136): “This philosopher did not contribute materially to the advancement of the science by the development of any new facts; but in his ‘History of Electricity’ he collected and arranged much useful information respecting the progress of the science.” Nevertheless, to him is due the first employment of the conductor supported by an insulating pillar, as described by Noad, who gives an account of Priestley’s electrical machine at Chap. IV of his “Manual”; and he is also the first to investigate upon an extensive scale the chemical effects of ordinary electricity. The observations of M. Warltire, a lecturer on natural philosophy, and Priestley’s own experiments in this line, made by passing the electric spark through water tinged blue by litmus, also through olive oil, turpentine, etc., as well as his researches more particularly upon the gases and upon the influence of the electric fluid in expanding solid bodies, are detailed at the “Electricity” chapter of the “Encycl. Brit.”

At pp. 660–665 of the fourth edition of his “History,” Priestley describes the experiments he made to illustrate what he called the lateral force of electrical explosions; that is, the tendency of the fluid to diverge, as is the case with lightning when any material obstruction lies in its path.

Perhaps the most important of all Dr. Priestley’s electrical discoveries (Thomson, “Hist. Roy. Soc.,” p. 445) was that charcoal is a conductor of electricity, and so good a conductor that it vies even with the metals themselves. When the conducting power of charcoal was tried by succeeding electricians, it was found to vary in the most unaccountable manner, sometimes scarcely conducting at all, sometimes imperfectly and sometimes remarkably well; a diversity naturally indicating some difference in the nature of the different specimens of English charcoal (Priestley’s “History,” etc., Part VIII. s. 3). Charcoal being examined by Mr. Kinnersley (at A.D. 1761), was also by him observed to vary in its conducting power. Oak, beech and maple charcoal he found to conduct satisfactorily; the charcoal from the pine would not conduct at all, while a line drawn upon paper by a heavy black lead pencil conducted pretty well (Phil. Trans., 1773, Vol. LXIII. p. 38).

REFERENCES.--Priestley’s letter to Dr. Franklin (Phil. Trans., Vol. LXII. p. 360) concerning William Henley’s new electrometer and experiments; likewise the Phil. Trans., Vol. LVIII. p. 68; Vol. LIX. pp. 57, 63; Vol. LX. p. 192; Vol. LXII. p. 359; and the abridgments by Hutton, Vol. XII. pp. 510, 600, 603; Vol. XIII. p. 36; “Trans. of the Amer. Phil. Soc.,” O. S., Vol. VI. part i. p. 190, containing proceedings of the Society on the death of Joseph Priestley; Wilkinson’s “Elements of Galvanism,” etc., London, 1804, Vol. II. pp. 74–80; Noad’s Lectures, No. 4, Knight’s edition, pp. 182, 183; “Library of Useful Knowledge,” London, 1829, Chap. “Electricity,” pp. 41 and 45; “Library of Literary Criticism,” C. W. Moulton, Buffalo, 1901–1902, Vol. IV. pp. 444–456; “Essays, Reviews and Addresses” by James Martineau, London, 1890, Vol. I. pp. 1–42; “Mém. de l’Institut” (Histoire), Tome VI. 1806, p. 29 for Elogium; “Essays in Historical Chemistry,” T. E. Thorpe, London, 1894, pp. 28, 110; “Science and Education,” by Thos. Henry Huxley, New York, 1894, pp. 1–37; “Scientific Correspondence of Jos. Priestley,” by H. C. Bolton, New York, 1902; Dr. Thos. H. Huxley, “Science Culture,” 1882, p. 102; Warltire, in Muirhead’s translation of Arago’s “Eloge de James Watt,” pp. 99, 100; also the appendix to the last-named work, p. 157 and note.

=A.D. 1767.=--Lane (Thomas--Timothy), a medical practitioner of London, introduces his discharging electrometer, which is now to be found described and illustrated in nearly all works on electricity.

It consists of a bent glass arm, one end of which is attached to a socket in the wire of the Leyden jar, while the other end holds a horizontal sliding brass rod, or spring tube, which bears a ball at each extremity. The rod is usually divided into inches and tenths, indicating the force of the discharge which takes place when the knob of the jar is placed in contact with the prime conductor of an electrical machine, and the charge is strong enough to leap from one to the other. In Mr. Lane’s experiments the shocks were twice as frequent when the interval between the balls was one twenty-fourth of an inch as when twice as much: from which he concluded that the quantity of electricity required for a discharge is in exact proportion to the distance between the surfaces of the balls.

A combination of the Lane and other electrometers was made by Mr. Cuthbertson, as shown at p. 528, Vol. II of Nicholson’s Journal of Natural Philosophy, and at p. 451, Vol. LVII of the Philosophical Transactions.

REFERENCES.--Phil. Trans. for 1805; Hutton’s abridgments, Vol. XII; p. 475; Cavallo, “Elements ... Phil.” 1825, Vol. II. p 197; Harris, “Electricity,” p. 103; Monthly Magazine, December 1805, and Tilloch’s Philosophical Magazine, Vol. XXIII. p. 253.

The Hutton abridgments contain, at p. 308, Vol. XV, the description of a new electrometer by Abraham Brook.

=A.D. 1768.=--Ramsden (Jesse), a very capable English manufacturer of mechanical instruments, member of the Royal Society and of the Imperial Academy of St. Petersburg, is said to be the first to construct an electrical machine wherein a plate of glass is substituted for the glass globe of Newton and of Hauksbee and for the glass cylinder of Gordon (at A.D. 1675, 1705 and 1742). The same claim which has been made for Martin de Planta, Swiss natural philosopher, appears to have no foundation. (See note at p. 401 of Ronalds’ “Catalogue.”)

REFERENCES.--Journal des Sçavans, November 1788, p. 744; Phil. Trans., 1783; “Chambers’ Encyclopædia,” 1868, Vol. III. p. 812; Mme. Le Breton, “Hist. et app. de l’Electricité,” Paris, 1884, pp. 61, 62.

=A.D. 1768.=--Molenier (Jacob), physician to the French King, Louis XV, writes “Essai sur le Mécanisme de l’Electricité” for the purpose of showing the utility of the application of the electric fluid in medical practice. At p. 60 he explains the effects and results when applications are made more particularly to the nerves, and at pp. 65–67 he gives certificates of many of the cures he has effected of gout, rheumatism, tumours, cancers, loss of blood, as well as of pains and aches of various descriptions.

REFERENCES.--Jallabert (A.D. 1749); Lovett (A.D. 1756); Bertholon (A.D. 1780–1781); Mauduyt (A.D. 1781); Van Swinden, “Recueil,” etc., La Haye, 1784, Vol. II. pp. 122–129 for the experiments of Sauvages, De La Croix, Joseph Elder von Herbert, H. Boissier and others; Thomas Fowler, “Med. Soc. of London,” Vol. III; M. Tentzel, “Collection Académique,” Tome XI; the works of L’Abbé Sans, Paris, 1772–1778; M. de Cazèles Masar’s “Mémoires et Recueils,” published 1780–1788, and reproduced in Vols. II and III of the “Mémoires de Toulouse”; Jacques H. D. Petetin, “Actes de la Soc. de Lyon,” p. 230; M. Partington, Jour. de Phys., 1781, Vol. I; Dr. Andrew Duncan’s “Medical Cases,” Edinburgh, 1784, pp. 135, 191, 235, 320; C. A. Gerhard, “Mém. de Berlin,” 1772, p. 141; Jour. de Phys., 1783, Vol. II; J. B. Bohadsch, “Dissertatio,” etc., Prague, 1751; _Phil. Trans._ for 1752; Patrick Brydone, Phil. Trans. for 1757; Geo Wilkinson, of Sunderland, “An account of good effects,” etc., in Medical Facts, etc., 1792, Vol. III. p. 52; M. Carmoy, “Observ. sur l’El. Med.,” Dijon, 1784; M. Cosnier, M. Maloet, Jean Darcet, etc.; “Rapport,” etc., 1783; Le Comus, “Dissertatio,” etc., 1761; Le Comus, “Osservazioni,” etc., 1776 (Jour. de Phys., 1775, Vols. V and VI; 1776, Vol. VII; 1778, Vol. I; 1781, Vol. II); Ledru, “Sur le traitement,” etc., 1783; Le Dr. Boudet, “De l’Elec. en Médecine,” conférence faite à Vienne le 6 Octobre, 1883.

=A.D. 1769.=--Bancroft (Edward Nathaniel), a resident physician of Guiana, openly expresses the belief that the shock of the torpedo is of an electrical nature. He alludes (“Natural History of Guiana”) also to the gymnotus electricus, which, he says, gives much stronger strokes than the torpedo; the shocks received from the larger animals being almost invariably fatal.

The discharge of the gymnotus has been estimated to be equal to that of a battery of Leyden jars of three thousand five hundred square inches, fully charged. At a later date, the American physicians, Garden and Williamson, showed that as the fluid discharged by that fish affects the same parts that are affected by the electric fluid; as it excites sensations perfectly similar; as it kills and stuns animals in the same manner; as it is conveyed by the same bodies that carry the electric fluid and refuses to be conveyed by others that refuse to take the fluid, it must be the electric fluid itself, and the shock given by the eel must be the electric shock.

Humboldt, speaking of the results obtained by M. Samuel Fahlberg, of Sweden, says: “This philosopher has seen an electric spark, as Walsh and Ingen-housz had done before him at London, by placing the gymnotus in the air and interrupting the conducting chain by two gold leaves pasted upon glass and a line distant from each other” (Edinburgh Journal, Vol. II. p. 249). Faraday, who gives this extract at paragraph 358 of his “Experimental Researches” says he could not, however, find any record of such an observation by either Walsh or Ingen-housz and does not know where to refer to that by Fahlberg. (See the note accompanying afore-named extract.)

REFERENCES.--Annales de Chimie et de Physique, Vol. XI; Phil. Trans. for 1775, pp. 94, 102 (letter of Alexander Garden, M.D.), 105, 395; “Acad. Berlin,” 1770, 1786; fifteenth series Faraday’s “Exper. Researches,” read December 6, 1838; Wheldon’s “Catalogue,” No. 74, 1870; Sir David Brewster’s “Edin. Jour. of Science,” 1826, Vol. I. p. 96, for the observations of Dr. Robert Knox; G. W. Schilling: at Ingen-housz, “Nouvelles Expériences,” p. 340, as well as at note, p. 439, Vol. I. of Van Swinden’s “Recueil,” etc., La Haye, 1784; also G. Schilling’s “Diatribe de morbo in Europâ penè ignoto,” 1770; article “Physiology” in the “Encycl. Brit.,” 1859, Vol. XVII. p. 671; Aristotle (B.C. 341), Scribonius (A.D. 50), Richer (A.D. 1671), Redi (A.D. 1678), Kaempfer (A.D. 1702), Adanson (A.D. 1751); Sc. Am. Suppl., No. 24, p. 375 (for M. Rouget’s observations on the gymnotus) and No. 457, p. 7300; M. Bajon, “Descrizione di un pesce,” etc., Milano, 1775 (Phil. Trans., 1773, p. 481); M. Vanderlot’s work on the Surinam eel, alluded to at p. 88 of “Voyage Zoologique,” by Humboldt, who published in Paris, during 1806 and also during 1819 special works on the gymnotus and upon electrical fishes generally.

=A.D. 1769.=--Cuthbertson (John), English philosophical instrument maker, issues the first edition of his interesting work on electricity and galvanism.

He is the inventor of the balance electrometer, employed for regulating the amount of a charge to be sent through any substance, as well as of an electrical condenser and of an apparatus for oxidating metals, all of which are respectively described at pp. 593, 614 and 620, Vol. VIII. of the 1855 “Encycl. Brit.”

At the end of Part VI of his “Practical Electricity and Galvanism,” Cuthbertson gives the conclusions he reached from his numerous experiments with wire. These, as well as Mr. George Adams’ own observations (“Essay,” etc., 1799, p. 285), proved that the quantity of electricity necessary to disperse a given portion of wire will be the same, even though the charged surface be greatly varied; and that equal quantities of electricity in the form of a charge will cause equal lengths of the same steel wire to explode, whether the jar made use of be of greater or less capacity (Nicholson’s Journal, Vol. II. p. 217).

During his many experiments Cuthbertson made the very extraordinary discovery that a battery of fifteen jars and containing 17 square feet of coated glass, which, on a very dry day in March 1796 could only be made to ignite from 18 to 20 inches of iron wire of ¹⁄₁₅₀ part of an inch in diameter, took a charge which ignited 60 inches when he breathed into each jar through a glass tube (Noad, “Manual,” p. 122; also Cuthbertson, “Prac. Elec. and Magnetism,” 1807, pp. 187, 188).

REFERENCES.--Cuthbertson’s communication to the “Emporium of Arts,” Vol. II. p. 193, regarding his experiments on John Wingfield’s “New Method of Increasing the Charging Capacity of Coated Electric Jars”; Cuthbertson’s “Electricity,” Parts VIII, IX and XI; Cuthbertson’s letter addressed to Nicholson’s Journal, Vol. II. p. 526, also Phil. Mag., Vol. II. p. 251. for electrometers; “Bibl. Britan.,” Vol. XXXIX. 1808, p. 97; Vol. XLVII. 1811, p. 233; Cuthbertson’s several works published at Amsterdam and Leipzig, 1769–1797, and alluded to in Phil. Mag., more particularly at Vols. XVIII. p. 358; XIX. p. 83; XXIV. p. 170; XXXVI. p. 259, as well as at p. 313, Vol. XII. of J. B. Van Mons’ Journal de Chimie; Nicholson’s Journal, Vols. II. p. 525; VIII. pp. 97, 205, and the New Series, Vol. II. p. 281; Gilbert’s Annalen, Vol. III. p. 1; “Bibl. Brit. Sc. et Arts,” Genève, 1808, Vol. XXXIX. p. 118; Noad’s “Manual,” p. 118; Van Marum (A.D. 1785); Harris, “Electricity,” p. 103, and his “Frictional Electricity,” p. 76; C. H. Wilkinson, “Elements of Galvanism,” etc., London, 1804, Vol. II. pp. 242, 266–268; Phil. Trans., 1782, for A. Brook’s electrometer, which apparatus is described in the latter’s work published, under the head of “Miscellaneous Experiments,” at Norwich, 1789, as well as in the “Electricity” article of the “Encycl. Britannica.”

=A.D. 1769.=--St. Paul’s Cathedral, London, is first provided with lightning conductors. Dr. Tyndall, who mentions this fact (Notes of Lecture VI, March 11, 1875) likewise states that Wilson, who entertained a preference for blunt conductors as against the views of Franklin, Cavendish and Watson, so influenced King George III that the pointed conductors on Buckingham House were, during the year 1777, changed for others ending in round balls.

In 1772, St. Paul’s Cathedral was struck by lightning, which “heated to redness a portion of one of its conductors consisting of a bar of iron nearly four inches broad and about half an inch thick.” In 1764, the lightning had struck St. Bride’s Church, London, and “bent and broke asunder an iron bar two and a half inches broad and half an inch thick” (Sturgeon, “Sc. Researches,” Bury, 1850, p. 360; Phil. Trans. for 1764 and 1762).

The Rev. James Pilkington, Bishop of Durham, published in London a detailed account of the partial destruction of St. Paul’s Church by lightning, June 4, 1561, which is also to be found at pp. 53–55 of Strype’s “Life of Grindall,” published in London, 1710, and of which an abstract appears under the A.D. 1754 date.

REFERENCES.--Sturgeon’s Annals, Vol. X. pp. 127–131; also, Biography of John Canton in “Encycl. Britannica”; Sir John Pringle, at A.D. 1777; Hutton’s abridgments of the _Phil. Trans._, Vol. XII. pp. 620–624.

=A.D. 1769.=--Mallet (Frederick) member of the Royal Society of Upsal and of the Stockholm Academy of Sciences, acting upon the observations of Anders Celsius (at A.D. 1740), is the first to make an attempt to determine the intensity of magnetism simultaneously at distant points. He ascertains that the number of oscillations in equal times at Ponoi, China (latitude, 67 degrees 4 minutes north; longitude, 41 degrees east) are the same as at St. Petersburg, Russia (59 degrees 56 minutes north latitude; 30 degrees 19 minutes east longitude).

REFERENCES.--Walker, “Magnetism,” Chap. VI; “Novi Commen. Acad. Sc. Petropol.,” Vol. XIV for 1769, part ii. p. 33; Le Monnier, “Lois du Magnétisme,” etc., 1776, p. 50; “Biog. Univ.,” Vol. XXVI. p. 258.

=A.D. 1770.=--The well-known work of Jas. Ferguson, F.R.S., which first appeared under the title of “Introduction or Lectures on Electricity,” now becomes still more popular under the head of “Lectures on Select Subjects,” etc. (Consult likewise his “Lectures on Electricity,” corrected by C. F. Partington, with appendix, London, 1825.)

In his first lecture he says that the most remarkable properties of the loadstone are: (1) it attracts iron and steel only; (2) it constantly turns one of its sides to the north and the other to the south, when suspended to a thread that does not twist; (3) it communicates all its properties to a piece of steel when rubbed upon it without losing any itself. He cites the experiments of Dr. Helsham, according to whom, says he, the attraction of the loadstone decreases as the square of the distance increases. He also treats of electrical attraction generally, and reports in the sixth lecture having “heard that lightning, striking upon the mariner’s compass, will sometimes turn it round and often make it stand the contrary way, or with the north pole towards the south.”

=A.D. 1770.=--Hell--Hehl--Heyl--Höll (Maximilian), Hungarian scientist (1720–1792), member of the Order of Jesuits and Professor of Astronomy at Vienna, who had great faith in the influence of the loadstone, invented a singular arrangement of steel plates to which he afterward attributed the cure “with extraordinary success” of many diseases, as well as of a severe attack of rheumatism from which he himself had long suffered.

He communicated his discovery to Friedrich Anton Mesmer, who was so strongly impressed by Hell’s observations that he immediately procured every conceivable description of magnet, with which he made many experiments that led to his introduction of animal magnetism, or rather mesmerism.

He is the author of many works, the most important being “Elementa Algebræ Joannis Crivelii magis illustrata et novis demonstrationibus et problematibus aucta,” Vienna, 1745; “Observ. Astronomicæ,” 1768, and “Auroræ Boreales Theoria nova,” 1776.

REFERENCES.--Beckmann, Bohn, 1846, Vol. I. p. 44; _Practical Mechanic_, Glasgow, 1843, Vol. II. p. 71; Van Swinden, “Recueil,” etc., La Haye, 1784, Vol. II. pp. 303, 304, etc.; J. Lamont, “Handbuch,” etc., p. 436; M. V. Burq, “Métallo thérapie,” Paris, 1853; “Biog. Générale,” Vol. XXIII. pp. 836–839; Schlichtegroll, “Nekrol.,” 1792, Vol. I. pp. 282–303; “Journal des Sçavans,” for July 1771, p. 499; Meusel, “Gelehrtes Teutschl”; Jer. de la Lande, “Bibliogr. Astronomique,” Paris, 1803, pp. 721–722.

=A.D. 1771.=--Morveau (Baron Louis, Bernard Guyton de), a very prominent French chemist and scientist, publishes at Dijon his “Reflexions sur la boussole à double aiguille,” and, later on, communicates to the Annales de Chimie, Vol. LXI. p. 70, and Vol. LXIII. p. 113, very valuable papers treating on the influence of galvanic electricity upon minerals, which are read before the French Institute.

REFERENCES.--Thomson, “Hist. of Chemistry,” Vol. II. 1831; the translation of Morveau’s letter to Guénaud de Montbéliard in Scelta d’ Opuscoli, Vol. XXXIII. p. 60; Berthollet, “Discours,” etc., 1816; “Biog. Univ.,” Tome XVIII. pp. 296–298; “Journal des Savants” for Jan. 1860; “Roy. Soc. Cat. of Sc. Papers,” Vol. III. pp. 99–102; Vol. VI. pp. 679–680; “Biog. Univ. et Portative,” etc., 1834, Vol. III. p. 701; Annales de Chimie, Vol. LXI. pp. 70–82; Sir Humphry Davy, “Bakerian Lectures,” London, 1840, p. 51.

=A.D. 1771.=--In a very interesting article published by the Gazette at Salem (Mass.), August 9, 1889, on the occasion of the formal opening of the new station of the Electric Lighting Company, the connection of that city with the progress of electricity was traced in the following manner:

“In 1771 Col. David Mason, a prominent figure among the patriots at Leslie’s Retreat, gave a course of lectures on ‘Electricity’ at his house near North Bridge. The Rev. John Prince, LL.D., minister of the First Church from 1779 to 1836, was especially interested in electricity, and is said to have made the first electrical machine in Salem, if not in the country. Col. Francis Peabody, assisted by Jonathan Webb, the apothecary, was much interested in the subject, and, in 1829, gave a series of lectures, illustrated with a machine made by himself, which had a glass plate wheel imported from Germany at a reported cost of $1500.

“Dr. Charles Grafton Page, another native of Salem, invented the first electric motor in which solenoids were used, and as early as 1850 constructed a motor which developed over 10 h.p. The next year he made a trial trip with his electro-magnetic locomotive over the Baltimore and Washington Railroad. Prof. Moses Gerrish Farmer lived in Pearl Street between the years 1850 and 1870, and, as far back as 1859, illuminated the house with divided electric lights--probably the first time that any house in the world was lighted by electricity. In 1847 Prof. Farmer had constructed and exhibited in public an electro-magnetic locomotive drawing a car holding two passengers, on a track one foot and a half wide.

“Many of Prof. Alexander Graham Bell’s early experiments were conducted in Salem, and the first lecture on the telephone in this country, if not in the world, was delivered by him before the Essex Institute in Lyceum Hall, February 12, 1877. The late Prof. Osbun, teacher of chemistry and physics at the Normal School in Salem, was also an electrical expert. He exhibited the first arc lights in Salem, and was the inventor of the storage battery system from which lights were exhibited.”

The advertisement of March 7, 1765, previously alluded to herein at Kinnersley, A.D. 1761, is as follows:

“A COURSE OF EXPERIMENTS ON THE

newly discovered Electrical Fire, to be accompanied with methodical LECTURES on the Nature and Properties of that wonderful Element will be exhibited by DAVID MASON, at his House opposite Mr. Thomas Jackson; Distiller, near Sudbury-Street.--To consist of two Lectures, at one Pistareen each Lecture.--The first Lectures to be on Monday and Thursday, and the Second on Tuesday and Friday Evenings every week, Weather permitting.

“OF ELECTRICITY IN GENERAL

“That the Electric Fire is a real Element,--That our Bodies at all Times contain enough of it to set an House on Fire,--That this Fire will live in Water,--A Representation of the seven Planets, shewing a probable Cause of their keeping their due Distances from each other, and the Sun in the Centre,--The Salute repulsed by the Ladies’ Fire, or Fire darting from a Lady’s Lips, so that she may defy any Person to salute her,--A Battery of Eleven Guns discharged by the Electric Spark, after it has passed through eight Feet of Water,--Several Experiments shewing that the Electric Fire and Lightning are the same, and that Points will draw off the Fire so as to prevent the Stroke,--With a number of other entertaining Experiments, too many to be inserted in an Advertisement.

“TICKETS to be had either at his House above or at his Shop in Queen-Street.”

Another advertisement, which appeared in the Salem Gazette of Tuesday, January 1, 1771, is thus worded: “To-morrow evening (if the Air be dry) will be exhibited A Course of Experiments in that instructive and entertaining branch of Natural Philosophy called Electricity; to be accompanied with Methodical Lectures on the nature and properties of the wonderful element; by David Mason, at his dwelling-house near the North-Bridge. The course to consist of two lectures, at a pistareen each lecture.”

=A.D. 1771.=--Milly (Nicolas Christiern de Thy, Comte de) French chemist, constructs compass needles of an alloy of gold and ferruginous sand. These needles answered well their purpose, as did also the brass needle owned by Christian Huyghens (alluded to at A.D. 1706), a fact which received the confirmation of Messrs. Du Lacque, Le Chevalier d’Angos and M. Arderon, while the latter further ascertained that he could impart a feeble though distinct magnetic force to a brass bar either by striking it or by means of the “double touch.”

REFERENCES.--The Comte de Milly’s “Mémoire sur la réduction des chaux métalliques par le feu electrique,” read before the Paris Academy May 20, 1774, brought about many controversial articles, notably from Sigaud de la Fond, Felice Fontana, Jean M. Cadet, Jean Darcet, G. F. Rouelle and Le Dru le Comus; “Biog. Univ.,” Vol. XXVIII. p. 312; Journal de Physique, Tome XIII. p. 393; Philosophical Transactions, Vol. L. p. 774; Duhamel, “Hist. Acad. Reg. Paris,” p. 184; Journal des Sçavans, Paris edition of December 1772, and Amsterdam edition of January 1773.

=A.D. 1772.=--Mesmer (Friedrich Anton), an Austrian physician, who, upon taking his diploma at Vienna in 1766, had published a thesis “On the Influence of the Planets upon the Human Body,” begins his investigations as to the power of the magnet with the steel plates of Father Hell. The results proved so favourable that Hell was induced to publish an account of them, but he incurred the displeasure of his friend by attributing the cures merely to the form of the plates.

Mesmer subsequently arrived at the conclusion that the magnet was incapable, by itself, of so acting upon the nerves as to produce the results obtained and that another principle was necessarily involved; he did not, however, give an explanation of it, and managed to keep his process a secret for quite a while. He had observed that nearly all substances can be magnetized by the touch, and in due time he announced his abandonment of the use of the magnet and of electricity in his production of what became known as mesmerism.

In 1779 he published his “Mémoire sur la découverte du magnétisme animal,” in which he says: “I had maintained that the heavenly spheres possessed a direct power on all of the constituent principles of animated bodies, particularly on the nervous system, by the agency of an all-penetrating fluid. I determined this action by the intension and the remission of the properties of matter and organized bodies, such as gravity, cohesion, elasticity, irritability and electricity. I supported this doctrine by various examples of periodical revolutions; and I named that property of the animal matter which renders it susceptible to the action of celestial and earthly bodies, animal magnetism. A further consideration of the subject led me to the conviction that there does exist in nature a universal principle, which, independently of ourselves, performs all that we vaguely attribute to nature or to art.”

The whole theory and practice of mesmerism was, however, openly rejected by one of Mesmer’s most capable pupils, Claude Louis Berthollet (A.D. 1803), a very distinguished French chemical philosopher, founder of the “Société Chimique d’Arcueil,” and who, in conjunction with Lavoisier (A.D. 1781), Guyton de Morveau (A.D. 1771), and Fourcroy (A.D. 1801), planned the new philosophical nomenclature which has since proved of such service to chemical science (“La Grande Encycl.,” Tome VI. p. 449; “Biog. Universelle,” Tome IV. pp. 141–149).

Mesmer gave all his manuscripts to Dr. Wolfart, of Berlin, who published in 1814, “Mesmerism ... as the general curative of mankind.” And it was one of Mesmer’s students, le Marquis de Puységur, who discovered magnetic somnambulism, an entirely new phenomenon in animal magnetism. (See the article “Somnambulism” in the “Encyl. Britannica,” as well as the numerous works therein quoted, relating to the above-named subjects, notably Mesmer’s own “Précis historique des faits relatifs au magnétisme animal, jusques en Avril 1781.”)

REFERENCES.--“Bulletin de l’Acad. de Méd.,” Paris, 1837, Tome I. p. 343, etc., and Tome II. p. 370; Blavatsky, “Isis Unveiled,” Vol. I. p. 172, etc.; “L’Académie des Sciences,” par Ernest Maindron, Paris, 1888, pp. 57–63; Richard Harte, “Hypnotism and the Doctors,” Vols. I and II, New York, 1903 (from Mesmer to De Puységur, Dupotet, Deleuze, Charcot, etc.); Robert Blakey, “History of the Philosophy of Mind,” London, 1850, Vol. IV. pp. 570–582, 639–645; the report of Dr. Franklin and other Commissioners ... against mesmerism, translated by Dr. William Bache, London, 1785; J. C. Schäffer, “Abhandlung,” etc., and “Kräfte,” etc. (1776), “Fernere,” etc. (1777), also “Journal Encyclopédique” for March 1777; Van Swinden, “Recueil,” etc., La Haye, 1784, Vol. II. pp. 373–446; C. H. Wilkinson, “Elements of Galvanism,” etc., Chapter XVIII; Champignon, “Etudes Physiques,” etc., Paris, 1843; “Archives du Magn. Animal,” published by M. Le Baron d’Hénin de Cuvillers, Paris, 1820–1823; “Report on Animal Magnetism” made by Charles Poyen Saint Sauveur, 1836; Dupotet’s “Manuel,” etc., Paris, 1868; Hale’s “Franklin in France,” 1888, Part II. chap. v. alluding to an interesting manuscript of T. Auguste Thouret now in the collection of the American Philosophical Society.

=A.D. 1772.=--Henley (William T.), F.R.S., invents the quadrant electrometer, an apparatus with which the quantity of electricity accumulated in a jar or battery can be measured through the amount of repulsion produced by the fluid upon a pith ball suspended from the centre of a graduated arc. It is generally attached to the prime conductor to measure the state of action of the electrical machine.

He is also the inventor of the universal discharger, for directing the charge of jars or batteries (Edw. Whitaker Gray--1748–1807--“Observations on manner glass is charged and discharged by the electric fluid” in Hutton’s abridgments, Vol. XVI. p. 407).

In the Philosophical Transactions for 1774, Henley and Nairne give an account of many curious experiments proving the superiority of points over balls as conductors. The same is shown by William Swift in the Phil. Trans., Vol. LXVIII. p. 155. (For Wm. Swift consult, besides, the Phil. Trans., Vol. LXIX. p. 454, and Hutton’s abridgments, Vol. XIV. pp. 314, 571.) Henley also states that the vapour of water is a conductor of electricity; that when the flame of a candle is introduced into the circuit and a Leyden jar is discharged through it, the flame always inclines toward the negative side; and he proves that electricity cannot effect a passage through glass (Phil. Trans., Vol. LXVIII. p. 1049). He likewise makes a number of experiments to determine the relative conducting power of the different metals according to the quantity of a wire, each of a given size, melted by equal electrical shocks passed through them, and finds the metals to hold the order following as conductors: gold, brass, copper silvered, silver, iron. It was also shown by Nairne that copper conducts better than iron, in the Phil. Trans. for 1780, Vol. LXX. p. 334.

REFERENCES.--Harris, “Rud. Electricity,” 1853, p. 93, and his “Frictional Electricity,” 1867, p. 23; “The Electrical Researches of the Hon. Hy. Cavendish,” Cambridge, 1879, Nos. 559, 568, 569, 580; Thos. Young, “Nat. Phil.” passim; Phil. Trans., Vol. LXIV. pp. 133, 389; Vol. LXVI. p. 513; Vol. LXVII. pp. 1, 85; also Hutton’s abridgments, Vol. XIII. pp. 323 (new electrometer), 512, 551, 659; Vol. XIV. pp. 90, 97, 130, 473; Transactions of the Humane Society, Vol. I. p. 63; Ronayne and Henley, “Account of Some Observations ...” London, 1772 (Phil. Trans., p. 137).

=A.D. 1772.=--Cavendish (Henry), F.R.S., eldest son of Lord Charles Cavendish, and a prominent English scientist, sometime called “The Newton of Chemistry” (“the most severe and cautious of all philosophers”--Farrar, 284), commences investigating the phenomena of electricity, the results of which study were duly communicated to the Philosophical Transactions. His papers embrace twenty-seven mathematical propositions upon the action of the electric fluid, and contain the first distinct statement of the difference between common and animal electricity.

Cavendish made many very important experiments upon the relative conducting power of different substances. He found that a solution of one part of salt in one part of water conducts a hundred times better, and that a saturated solution of sea-salt conducts seven hundred and twenty times better than fresh water, also that electricity experiences as much resistance in passing through a column of water one inch long as it does in passing through an iron wire of the same diameter four hundred million inches long, whence he concludes that rain or distilled water conducts four hundred million times less than iron wire.

He decomposed atmospheric air by means of the electric spark, and he successfully demonstrated the formation of nitric acid by exploding a combination of seven measures of oxygen with three of nitrogen. The latter he did on the 6th of December, 1787, with the assistance of Mr. George Gilpin, in presence of the English Royal Society. (For George Gilpin, consult “Bibl. Britan.,” Vol. XXXVI, 1807, p. 3; Phil. Trans. for 1806.)

He improved upon Priestley’s experiments after studying thoroughly the power of electricity as a chemical agent. In one of his experiments he fired as many as five hundred thousand measures of hydrogen with about two and a half times that quantity of atmospheric air, and having by this means obtained 135 grains of pure water, he was led to the conclusion which Mr. Watt had previously maintained, that water is composed of two gases, viz. oxygen and hydrogen.

He explains why no spark is given by the electrical fishes: the latter may contain sufficient electricity to give a shock without being able to make it traverse the space of air necessary for the production of a spark, as the distance through which the spark flies is inversely (or rather in a greater proportion) as the square root of the number of jars in operation.

For an account of his experiments anticipating Faraday’s discovery of the specific inductive capacity of various substances, see Chap. XI. pp. 69–142 of Gordon’s “Physical Treatise,” etc., London, 1883. See, likewise, J. Clerk Maxwell’s “Electrical Researches,” etc., Cambridge, 1879, pp. liii-lvi, as well as references therein made, more particularly at articles Nos. 355–366, 376; also the notes 27, 29 as per Index at pp. 450 and 453; Phil. Trans., Vol. CLXVII (1877), p. 599; Sparks’ edition of Franklin’s “Works,” Vol. V. p. 201.

REFERENCES.--Dr. G. Wilson’s “Life and Works of Hon. Henry Cavendish,” London, 1851; Sturgeon’s Annals, Vol. VI. pp. 137, 173, etc.; Noad, “Manual,” etc., pp. 14, 161; Harris, “Electricity,” pp. 136, 140; Harris, “Frictional Electricity,” pp. 23 and 45; Whewell, “Hist. of the Ind. Sciences,” 1859, Vol. II. pp. 203–206, 273–275, 278; C. R. Weld, “Hist. Roy. Soc.,” for Lord Charles Cavendish, Vol. II. pp. 171, 176–185, 221; T. E. Thorpe, “Essays in Historical Chemistry,” London, 1894, pp. 70, 110; Thomas Thomson, “Hist. Roy. Soc.,” London, 1812, pp. 456, 457, 471; Sir William Thomson’s “Works,” 1872, pp. 34, 235; Phil. Trans. for 1776, Vol. LXVI. p. 196; Thos. Young, “Lectures,” 1807, Vol. I. pp. 658, 664, 751, and Vol. II. p. 418.

=A.D. 1773.=--Walsh (John), F.R.S., demonstrates the correctness of Dr. Bancroft’s opinion that the shock of the torpedo is of an electrical nature, resembling the discharge from a Leyden jar. In the letter announcing the fact, which he addressed to Franklin, then in London, he says: “He, who predicted and showed that electricity wings the formidable bolt of the atmosphere, will hear with attention that in the deep it speeds a humbler bolt, silent and invisible; he, who analyzed the electric phial, will hear with pleasure that its laws prevail in animated phials; he, who by reason became an electrician, will hear with reverence of an instructive electrician gifted at its birth with a wonderful apparatus, and with skill to use it.”

Mr. Walsh’s experiments were made off Leghorn, in company with Dr. Drummond, as stated in Phil. Trans., 1775, p. 1, and were confirmed by Johan Ingen-housz as well as by the Italian naturalist, Lazaro Spallanzani (at A.D. 1780). The last named found the torpedo shocks strongest when it lay upon glass, and that when the animal was dying the shocks were not given at intervals, but resembled a continual battery of small shocks: three hundred and sixteen of them have been felt in seven minutes.

REFERENCES.--Leithead, “Electricity,” p. 135; Gray, “Elements of Natural Philosophy,” 1850, p. 323; “Electrical Researches of Lord Cavendish,” 1879, pp. xxxv, xxxvi and 395–437; Fifth Dissertation of “Encycl. Britannica,” 8th ed. p. 738; Phil. Trans. for 1773, 1774, 1775 and 1776; also Hutton’s abridgments, Vol. XIII. p. 469; “Chambers’ Ency.,” 1868, Vol. III. p. 821; “People’s Cyclopædia,” 1883, Vol. I. p. 628; Kaempfer (A.D. 1702); Sc. American Supplement, No. 457, pp. 7300, 7301, “Lettera dell’ Abate Spallanzani al Signore Marchese Lucchesini,” Feb. 23, 1783, inserted in the Gothaische Gelehrte Zeitungen for 1783, p. 409. See also the experiments of Dr. Ingram, of Kaempfer and of Borelli, described in Van Swinden’s “Recueil,” etc., La Haye, 1784, Vol. II; Wilkinson’s “Galvanism,” 1804, Vol. I. pp. 318, 324; G. W. Schilling, “Diatribe de morbo,” etc., 1770, and Friedrich von Hahn in the preface to Schilling’s “De Lepra,” etc., 1778, as well as at pp. 436–442, Vol. I and at note, p. 160, Vol. II of Van Swinden’s “Recueil,” already noted; J. B. Leroy and M. Saignette “Sur. l’élect. de la Torpille,” etc. (Jour. de Phys., 1774, Vol. IV and for 1776, Vol. VIII); “Annales du Musée d’Hist. Nat.,” p. 392; R. A. F. De Réaumur, “Mém. de l’acad. des Sc. de Paris” for 1714; C. Alibert, “Eloges,” etc., Paris, 1806.

=A.D. 1773.=--Odier (Louis), a well-known Swiss physician, thus addresses a lady upon the subject of an electric telegraph: “I shall amuse you, perhaps, in telling you that I have in my head certain experiments, by which to enter into conversation with the Emperor of Mogol or of China, the English, the French, or any other people of Europe, in a way that, without inconveniencing yourself, you may intercommunicate all that you wish, at a distance of four or five thousand leagues in less than half an hour! Will that suffice you for glory? There is nothing more real. Whatever be the course of those experiments, they must necessarily lead to some grand discovery; but I have not the courage to undertake them this winter. What gave me the idea was a word which I heard spoken casually the other day, at Sir John Pringle’s table, where I had the pleasure of dining with Franklin, Priestley and other great geniuses.”

REFERENCES.--Necrology of Prof. Odier in “Bibl. Britan.,” Vol. IV. N. S., 1817, pp. 317–328; see also allusion to Odier at Schwenter (A.D. 1600), and in the report of Bristol meeting of the British Association, August 25, 1875; also Chambers’ “Papers for the People,” 1851, El. Com., p. 6; Bertholon, “Elec. du Corps Humain,” 1786, Vol. I. p. 357.

=A.D. 1773.=--Hunter (John), a native of Scotland, “by common consent of all his successors, the greatest man that ever practiced surgery,” gives at p. 481 of the Phil. Trans. for 1773 his observations on the anatomical structure of the raia torpedo.

The electricity of the animal, he found, is generated by organs on each side of the cranium and gills, somewhat resembling a galvanic pile, and consisting wholly of perpendicular columns reaching from the upper to the under surface of the body. Dr. Walsh gave him for examination a fish about eight inches long, two inches thick and twelve inches broad, and Hunter found in each electrical organ as many as 470 columns; but in a very large fish, four and a half feet long and weighing 73 pounds, he counted as many as 1182 in each organ.

He remarks that there is no part of any animal with which he is acquainted, however strong and constant its natural action, which has so great a proportion of nerves; and he concludes that, if it be probable these nerves are not necessary for the purposes of sensation or action, they are subservient to the formation, collection or management of the electric fluid.

REFERENCES.--Phil. Trans. for 1773, p. 461; for 1775, p. 465 (gymnotus electricus); for 1776, p. 196; the Phil. Trans., Vol. LXIII. p. 481, (torpedo); Vol. LXV. p. 395 (gymnotus); and Hutton’s abridgments, Vol. XIII. pp. 478, 666; also John Davy’s account in Phil. Trans. for 1832, p. 259; “Am. Trans.,” Vol. II. p. 166; Nicholson’s Journal, Vol. I. p. 355; _Journal de Physique_, Vol. XLIX. p. 69; Becquerel et Brachet, _Comptes Rendus_, III. p. 135; Carlo Matteucci, “Recherches,” Genève, 1837; Delle Chiage, on the organs of the torpedo; Geo. Adams, “Essay on Electricity,” etc., 1785, p. 315; D. J. N. Lud. Roger, “Specimen Physiologicum,” etc., Göttingæ, 1760; Dr. Buniva’s experiments recorded in “Journal de Littér. Médicale,” Tome II. p. 112; Leithead, “Electricity,” Chap. XII; _Scient. Am. Suppl._, No. 457, pp. 7300–7302. See also the account of his having been the first to observe the galvanic sensation of light in the experiment on the eyes, published in “Opuscoli Scelti,” Vol. XXII. p. 364.

=A.D. 1774.=--At p. 16 of the third volume of Dr. Wm. Hooper’s “Rational Recreations,” etc., there is given a fine illustration of the electrical machine made by Dr. Priestley, and mention is made of the fact that, since the publication of the latter’s “History and Present State of Electricity,” he contrived, to be placed on the top of his house, a windmill by which the machine could be occasionally turned.

Much of the remainder of the volume is given to all kinds of experiments in the line of electricity and magnetism.

=A.D. 1774.=--Lesage (Georges Louis, Jr.), a Frenchman living at Geneva, Switzerland, makes in that city the first real attempt to avail of frictional electricity for the transmission of signals between two distant points (see C. M., or Charles Morrison, at A.D. 1753). His apparatus consists of twenty-four metallic wires insulated from each other and communicating with separate electrometers formed of small balls of elder held by threads and each marked with different letters of the alphabet. Whenever the electric current was transmitted, the balls indicated the desired letter.

Lesage was not, however, satisfied with a telegraph upon so small a scale as to be utilized only in one building, and on the 22nd of June 1782 he addressed a letter to M. Pierre Prévost, at Geneva, on the subject of “a ready and swift method of correspondence between two distant places by means of electricity.” This, he says, had occurred to him thirty or thirty-five years before, and had been “then reduced to a simple system, far more practicable than the form with which the new inventor has endowed it.” He employed a subterranean tube of glazed earthenware, divided at every fathom’s length by partitions with twenty-four separate openings intended to hold apart that number of wires, the extremities of the wires being “arranged horizontally, like the keys of a harpsichord, each wire having suspended above it a letter of the alphabet, while immediately underneath, upon a table, are pieces of gold leaf, or other bodies that can be as easily attracted, and are at the same time easily visible.” Upon touching the end of any wire with an excited glass tube, its other extremity would cause the little gold leaf to play under a certain letter, which would form part of the intended message.

Georges Louis Lesage (sen.) wrote a work on “Meteors,” etc., published at Geneva in 1730, and alluded to in Poggendorff, Vol. I. p. 1433.

REFERENCES.--Abbé Moigno, “Traité,” etc., 2nd ed. Part II. chap. i. p. 59; Ed. Highton, “The Electric Telegraph,” 1852, p. 38; Journal des Sçavans, September 1782, p. 637; Pierre Prévost, “Notice,” etc., 1805, pp. 176–177.

=A.D. 1774.=--Wales (William), English mathematician and the astronomer of Captain Cook during the expeditions of 1772, 1773 and 1774, is the first to make scientific observations relative to the local attraction of a ship upon mariners’ compasses. While on his way from England to the Cape and during his passage through the English Channel he found differences of as much as 19 degrees to 25 degrees in the azimuth compass.

REFERENCES.--Sturmy, at A.D. 1684; also Wales and Bayly’s “Observations on Cook’s Voyages,” p. 49.

=A.D. 1775.=--Gallitzin (Dmitri Alexewitsch Fürst, Prince de), an able Russian diplomat and scientist, carries on at the Hague, between the 4th of June, 1775, and the commencement of the year 1778, a series of experiments upon atmospherical electricity, the results of which he communicates to the St. Petersburg Academy of Sciences in a Memoir entitled “Observations sur l’Electricité naturelle par le moyen d’un cerf-volant.” Therein he states that the presence of electricity was always noticeable whenever he raised his kite, whether in the night or in the daytime, as well as during hot, dry, or damp weather, and he ascertained that electricity is generally positive during calm weather and more frequently negative when the weather is stormy.

He also observed during an extensive course of experiments upon animals that hens’ eggs hatch sooner when they are electrified, thus confirming the previous observations of Koeslin and Senebier, and he gives an account of the effects of battery shocks upon various species. He cites the case of a hen which had sustained the shock of sixty-four jars and appeared dead, but which revived and lived thirty-two days; and he gives the report of the dissection made by M. Munichs, as well as the very curious observations upon it noted at the time by M. Camper.

REFERENCE.--Bertholon, “Elec. du Corps Humain,” 1786, Vol. I. pp. 13–14, 66, and Vol. II. p. 48, etc.; “Anc. Mém. de l’acad. Belge,” Vol. III. p. 3, showing preference for the pointed form of electrical conductors; “Mercure de France,” 1774, p. 147; “Biog. Univ.,” Tome XV. p. 425; “Mém. de l’Acad. ... de Bruxelles,” Vol. III. p. 14; Journal de Physique, Vols. XXI and XXII for 1782 and 1783; “Opuscoli Scelti,” Vol. II. p. 305.

=A.D. 1775.=--Lorimer (Dr. John), “a gentleman of great knowledge on magnetics” (1732–1795), describes his combined dipping and variation needle for determining the dip at sea, which he calls universal magnetic needle or observation compass in a letter to Sir John Pringle, Bart., copied in Philosophical Transactions, Vol. LXV. p. 79. This apparatus is also to be found described in Lorimer’s “Essay on Magnetism,” etc., 1795, as well as at p. 168 of Cavallo’s “Treatise on Magnetism” published in 1787; and, at p. 333 of the latter work, the Doctor endeavours to explain the causes of the variation of the magnetic needle.

REFERENCES.--For Lorimer, consult Hutton’s abridgments, Vol. XIII. p. 593, and, for dipping needles, refer to the same volume of Hutton, p. 613, wherein especial mention is made of those of Thomas Hutchins. The dipping needle of Robert Were Fox is described in the “Annals of Electricity,” as well as at p. 411, Vol. II. of “Abstract of Papers of Roy. Soc.,” and the two dipping needles of Edward Nairne are described in Phil. Trans. for 1772, p. 496. Capt. Henry Foster made a report on changes of magnetic intensity ... in dipping and horizontal needles, to be found in Phil. Trans. for 1828, p. 303 (“Abstracts Sc. Papers ... Roy. Soc.,” Vol. II. pp. 290–296, 344).

=A.D. 1775.=--Cavallo (Tiberius), a distinguished Italian natural philosopher, publishes in London “Extraordinary Electricity of the Atmosphere at Islington,” which volume was reprinted by Sturgeon, and contains his many experiments and important observations upon the line indicated by Franklin. This work was followed in 1777, 1782, 1787, 1795, 1802 by his “Complete Treatise on Electricity,” etc.; by his “Essay on the Theory and Practice of Medical Electricity” (London, 1780, 1781; Leipzig, 1782, 1785; Naples, 1784); and during 1787 was also published in London the first edition of his “Treatise on Magnetism,” a supplement to which appeared eight years later.

He had made many very remarkable observations during the year 1787 on the phenomena of electricity in glass tubes containing mercury, and he had particularly experimented with various substances floating upon mercury in order to test their magnetism.

Before the year 1795 he contrived what he called a multiplier of electricity, a good illustration of which is to be found, more particularly, opposite p. 270, Vol. II. of his “Elements,” etc., published at Philadelphia in 1825. It consisted of two brass plates insulated upon glass pillars, and of a third plate which could be insulated or uninsulated at will, and which, turning on a pivot, or rather a movable arm, could be made to successively convey electricity from one plate to the other until the desired quantity was accumulated. (For the multiplier, see Jean Damel Colladon in “Bibl. Britan.,” Vol. XXIX, N.S. for 1825, p. 316.)

Cavallo also invented a small electroscope and a condenser of electricity. The latter consisted of an insulated tin plate between the sides of a wooden frame lined with gilt paper, one edge of the plate being connected with the body containing the electricity, and the condensation making itself observable at the opposite edge by the electroscope.

In the fourth edition of his “Treatise on Electricity” (1795), which, like the previous editions, was freely translated into other languages, will be found at pp. 285–296 of the third volume mention of the possibility of transmitting intelligence by combinations of sparks and pauses. For his experiments he made use of brass wires 250 English feet in length, and his electric alarm was based upon either the explosion of a mixture of hydrogen and of oxygen, or of gunpowder, phosphorus, phosphuretted hydrogen, etc., fired by the Leyden phial (vide Bozolus at A.D. 1767). It is in Vol. I. p. 358 of the afore-named fourth edition that Cavallo explains the mode of action of the charged Leyden jar. His concluding words deserve reproduction: “Which shows that one side of a charged electric may contain a greater quantity of electricity than that which is sufficient to balance the contrary electricity of the opposite side. This redundant electricity should be carefully considered in performing experiments of a delicate nature.” The same is expressed in other words in the 1825 American edition of his “Natural Philosophy,” Chap. IV. Therein he asserts that glass is impervious to the electric fluid, saying: “If the additional electric fluid penetrates a certain way into the substance of the glass, it follows that a plate may be given so thin as to be permeable to the electric fluid, and, of course, incapable of a charge; yet glass balls blown exceedingly thin, viz. about the six-hundredth part of an inch thick, when coated, etc., were found capable of holding a charge.” (Consult Cavendish’s experiments which produced this remarkable discovery, in Phil. Trans., Vols. LXXV and LXXVIII.)

An electrical machine used by Cavallo in 1777 had a glass cylinder rotated by means of a cord passing around the neck and the wheel, also a cushion (amalgamated with two parts of mercury, one of tinfoil, some powdered chalk and grease) holding a silk flap and freely moving along a groove, and provided with a prime conductor resting on glass legs and with collecting points.

REFERENCES.--Sturgeon, “Lectures,” London, 1842, p. 12; Young’s “Lectures,” London, 1807, Vol. I. pp. 682, 686, 694, 714; Nicholson’s Journal, 1797, Vol. I. p. 394; Du Moncel, “Exposé,” Vol. III; Aikin’s “General Biography,” Vol. X; _Phil. Transactions_, 1776, Vol. LXVI. p. 407; 1777, Vol. LXVII. pp. 48, 388; 1780, Vol. LXX. p. 15; 1786, p. 62; 1787, p. 6; 1788, pp. 1 and 255, and 1793, p. 10 (Volta’s letters); likewise Hutton’s abridgments, Vol. XVI. pp. 57, 170, 354, 449; Vol. XIV. pp. 60, 129, 180, 608; see also “Encycl. Britannica,” art. “Magnetism,” Chap. III. s. 1. for Cavallo’s “Observations on the Magnetism of Metals,” etc.

=A.D. 1775.=--Bolten (Joach. Fred.), a German physician, is the author of “Nachricht von einem mit dem Künstlichen magneten gemachten Versuchein einer Nerven-Krankheit” (Hamburg, 1775), the title of which is here given in full, as the work is not usually found recorded in publications and is considered to be of excessive rarity.

Contrary to the accepted belief of many at the time, Bolten asserts that the application of magnetic plates for the cure of nervous and other affections is not only useless, but has, in many instances, been shown to greatly increase pain. This is proven by M. Fonseca in his Journal, which forms part of the above-named work; by Andry and Thouret (“Obs. et Rech sur ... l’Aimant ...” 8, pp. 599, 661), and by J. David Reuss (“Repertorium,” Vol. XII. p. 18), as well as by observations recorded in another very scarce work, translated into Dutch during 1775 by the celebrated physicist, J. R. Deimann, under the title of “Geneeskundige Proefneeming met den door Koast gemaakten Magneet, door den Heere T. C. Unzer.”

REFERENCES.--Magnetical cures by different processes are treated of more particularly by Goclenius R., Jr., “Tract. de Mag. Curatione ...” Marp., 1609; J. Robertus, “Curationis Magneticæ ...” Luxemb., 1621, Coloniæ, 1622; Charlton, “A Ternary of Paradoxes ...” London, 1650; G. Mascuelli, “De Medicina Magnetica,” Franckfort, 1613, translated by W. Maxwell (Maxvellus), 1679–1687; Tentzelius, “Medicina Diastatica ...” 1653; A. Van Leuwenhoeck (Phil. Trans., Vol. XIX for 1695–1697, as shown below); J. N. Tetens, “Schreiben ... Magnetcuren,” Bützow and Wismar, 1775; Jacques de Harsu, “Receuil des Effets ...” Geneva, 1783; W. Pigram, “Successful Application ...” (Phil. Mag., Vol. XXXII. p. 154); Kloerich, F. W., “Versuche ...” (“Götting. Anzeigen,” 1765), “Von dem Medicin ...” Göttingen, 1766; M. Mouzin, “De l’emploi ... Maladies,” Paris, 1843. See likewise A.D. 450, and Hell at A.D. 1770.

For Anthony Van Leuwenhoeck, consult the Phil. Trans. for 1695–1697, Vol. XIX. No. 227, p. 512; Vol. XXXII. p. 72; also the abridgments of Reid and Gray, Vol. VI. p. 170, and of Eames and Martyn, Vol. VI. part. ii. pp. 277–278.

=A.D. 1775.=--Volta (Alessandro), an Italian natural philosopher and Professor at the University of Pavia, who had already, in 1769, addressed to Beccaria a Latin dissertation, “De Vi Attractivâ ignis electrici,” etc., makes known his invention of the electrophorus, a sort of perpetual reservoir of electricity. This consists of two circular metallic plates having between them a round disc of resin, which is excited by being struck a number of times with either a silk kerchief or pieces of dry warm fur or flannel. During 1782 he discovered what he called an electrical condenser, wherein the disc of resin is replaced by a plate of marble or of varnished wood. With this he is reported (Philosophical Transactions, Vol. LXXII) to have ascertained the existence of negative electricity in the vapour of water, in the smoke of burning coals, and in the gas produced by a solution of iron in weak sulphuric acid. An account of the above named and of other discoveries, as well as of various experiments, appears in letters addressed by him to Prof. Don Bassiano Carminati, of the Pavia Medical University, April 3, 1792, and to Tiberius Cavallo, Sept. 13, and Oct. 25, 1792, as shown in the Philosophical Transactions of the Royal Society, which institution gave him its gold Copley medal.

Volta’s crowning effort lies in the discovery of the development of electricity in metallic bodies and in the production of the justly famous pile which bears his name. The latter consisted of an equal number of zinc and copper discs separated by circular plates of cloth, paper or pasteboard soaked in salt-water or dilute acid, all being suitably connected to develop a large quantity of the electric fluid. Thus, says Dr. Dickerson in his address at Princeton College, Volta gave to the world that new manifestation of electricity called Galvanism. In that form this subtle agent is far more manageable than in the form of static electricity; and by the use of galvanic batteries a current of low tension, but of enormously greater power, can be maintained with little difficulty; whereas static electricity is like lightning, and readily leaps and escapes on the surfaces on which it is confined.

“It was Volta who removed our doubtful knowledge. Such knowledge is the early morning light of every advancing science, and is essential to its development; but the man who is engaged in dispelling that which is deceptive in it, and revealing more clearly that which is true, is as useful in his place and as necessary to the general progress of science as he who first broke through the intellectual darkness and opened a path into knowledge before unknown” (Faraday’s “Researches”).

The last mentioned discovery, though made in 1796, was first announced only on the 20th of March, 1800, in a letter written from Como to Sir Joseph Banks, by whom it was communicated to the Royal Society. It was publicly read June 26, 1800 (Phil. Trans. for 1800, Part II. p. 408).

At pp. 428–429 of “La Revue Scientifique,” Paris, April 8, 1905, will be found a review of J. Bosscha’s work entitled “La correspondance de A. Volta et de M. Van Marum,” published at Leyden. Bosscha calls especial attention to letters numbered XIII and XIV, dated respectively August 30 and October 11, 1792, wherein Volta describes his construction of the apparatus which, as already stated, was not made known until March 20, 1800. M. Bosscha’s work is also referred to in the “Journal des Savants” for August 1905.

Volta, at about the same period, constructed an electrical battery, which has been named La Couronne de Tasses (the crown of cups), and which consisted of a number of cups arranged in a circle, each cup containing a saline liquid and supporting against its edges a strip of zinc and one of silver. As the upper part of each zinc strip was connected by a wire with a strip of silver in the adjoining cup, the silver strip of the first cup and the zinc strip of the last cup formed the poles of the battery. It is said that twenty such combinations decomposed water, and that thirty gave a distinct shock.

On the 16th, 18th and 20th of November 1800 (Brumaire an. IX), Volta, who had obtained permission of the Italian Government to go to Paris with his colleague Prof. Brugnatelli, delivered lectures and experimented before the French National Institute (Sue, “Histoire du Galvanisme,” Vol. II. p. 267). As a member of the latter body, Bonaparte, the First Consul, who had attended the second lecture and witnessed the electro-chemical decomposition of water, proposed that a gold medal be stuck to commemorate Volta’s discovery, and that a commission be formed to repeat all of Volta’s experiments upon a large scale. The commission embraced such prominent men as Laplace, Coulomb, Hallé, Monge, Fourcroy, Vauquelin, Pelletan, Charles, Brisson, Sabathier, Guyton De Morveau and Biot. Biot, the chairman of the commission, made a report December 11, 1800, which appears in Vol. V of the Mémoires de l’Institut National de France, as well as in the Annales de Chimie, Vol. XLI. p. 3. In addition to the gold medal, Volta received from Bonaparte the sum of six thousand francs and the cross of the Legion of Honour.

To Volta has been attributed the fact of having, as early as 1777, entertained the idea of an electric telegraph, although nothing more appears to be on record in relation to the matter. Fahie quotes a letter of Sir Francis Ronalds, alluding to an autograph manuscript, dated Como, April 15, 1777, and gives its translation by César Cantu, wherein Volta states that he does not doubt the possibility of exploding his electrical pistol at Milan, through wires supported by posts, whenever he discharges a powerful Leyden jar at Como.

REFERENCES.--Arago, “Eloge Historique de Volta” and “Notices Biographiques,” Tome I. p. 234 (“Raccolta Pratica di Scienze,” etc. for March and April 1835); London Times of January 26, 1860; the eulogies pronounced by Giorn. Fogliani at Como and by G. Zuccala at Bergamo, the year of Volta’s death, 1827; P. Sue, “Histoire du Galvanisme,” Tome II. p. 267; Journal de Leipzig, Tome XXXIV; Scelta d’ Opuscoli, Vols. VIII. p. 127; IX. p. 91; X. p. 87; XII. p. 94; XIV. p. 84; XXVIII. p. 43; XXXIV. p. 65; Opuscoli Scelti, Vols. I. pp. 273, 289; VII. pp. 128, 145; XV. pp. 213, 425; XXI. p. 373; “Mem. dell’ I. R. Istit. Reg. L. V.,” Vol. I. p. 24; “Mem. dell’ Istit. Nazion. Ital.,” Vol. I. p. 125; “Memor. Soc. Ital.,” Vols. II., pp. 662, 900; V. p. 551; “Bibl. Fisica d’Europa” for 1788; “Giornale Fis.-Med.,” Vols. I. p. 66; II. pp. 122, 146, 241, 287; III. p. 35; IV. p. 192; V. p. 63; “Giornale dell’ Ital. Lettera,” etc., Vol. VIII. p. 249; L. V. Brugnatelli, “Annali di Chimica,” etc., Vols. II. p. 161; III. p. 36; V. p. 132; XI. p. 84; XIII. p. 226; XIV. pp. 3, 40; XVI. pp. 3, 27, 42; XVIII. pp. 3, 7; XIX. p. 38; XXI. pp. 79, 100, 163; XXII. pp. 223–249 (Aless. Volta and Pietro Configliachi); Aless. Volta and Angelo Bellani, “Sulla formazione,” etc., Milano, 1824; F. A. C. Gren, Neues Journal der Physik, Vols. III and IV for 1796 and 1797; Rozier, Observ., Vols. VII, XXII and XXIII for 1776, 1873; J. B. Van Mons, Journal de Chimie, No. 2, pp. 129, 167; Sédillot, “Receuil Per. de la Soc. de Méd. de Paris,” IX. pp. 97, 231; Journal de Phys., Vols. XXIII. p. 98; XLVIII. p. 336; LI. p. 334; LXIX. p. 343; Annales de Chimie, Vols. XXX. p. 276; XLIV. p. 396; Nicholson’s Journal, Vol. XV. p. 3; Phil. Tr. for 1778, 1782 and 1793; “Soc. Philom.,” An. IX. p. 48, An. X. p. 74; “Bibl. Brit.,” Vol. XIX. p. 274; Le Correspondant for August, 1867, p. 1059, and Les Mondes, December 5, 1867, p. 561; Highton, “The Elec. Tel.,” 1852, pp. 13 and 28; Robertson, “Mémoires Récréatifs,” 1840, Vol. I. chaps, x. and xiii.; Miller, “Hist. Philos. Illustrated,” London, 1849, Vol. IV. p. 333, note; Achille Cazin, “Traité théorique et pratique des piles électriques,” Paris, 1881; “Mémoires de l’lnstitut” (Hist.) An. XII. p. 195; Andrew Crosse, “Experiments in Voltaic Electricity,” London, 1815 (Phil. Mag., Vol. XLVI. p. 421, and Gilbert’s “Annalen,” Bd. s. 60); “Lettere sulla Meteorol.,” 1783; Theod. A. Von Heller, in Gilb. “Annal.,” Vols. IV and VI, 1800; and Gren’s Neues Journ., 1795, 1797; “L’Arc Voltaique,” by M. Paul Janet, in “Revue Générale des Sciences,” May 15, 1902, pp. 416–422; “L’Académie des Sciences,” par Ernest Maindron, Paris, 1888, pp. 245–251; “Philosophical Magazine,” Vol. IV. pp. 59, 163, 306; Vol. XIII. pp. 187–190 [re prize founded by Napoleon); Vol. XXI. p. 289 (electrophorus); Vol. XXVIII. p. 182 (theory of Pierre Hyacinthe Azais), and p. 297 (Paul Erman on “Voltaic Phenomena”); Thomson, “Hist. of Chemistry,” Vol. II. pp. 251–252; “Dict. de Gehler,” Vols. III. p. 665; VI. pp. 475, 484; Thomas Thomson, “Hist. of the Royal Soc.,” London, 1812, p. 451; Young’s “Lectures,” Vol. I. pp. 674, 677, 678, 683; see likewise the “Theory of the Action of the Galvanic Pile,” as given by Dr. Wm. Henry at s. 5 Vol. I. of his “Elements of Experimental Chemistry,” London, 1823; also Nicholson’s Journal for Henry’s essay in Vol. XXXV. p. 259; M. De Luc’s papers in Vol. XXXII. p. 271, and Vol. XXXVI. p. 97; Mr. Singer on the “Electric Column” in Vol. XXXVI. p. 373; Dr. Bostock’s essay in Thomson’s “Annals,” Vol. III. p. 32; Sir H. Davy’s chapter on “Electrical Attraction and Repulsion,” in his “Elements of Chem. Philos.,” p. 125; the first volume of Gay-Lussac and Thénard’s “Recherches”; Johann Mayer, “Abhandlungen ... Galvani, Valli, Carminati u. Volta,” etc., Prague, 1793; Lehrbuch der Meteor., von L. F. Kaemtz, Halle, 1832, Vol. II. pp. 398, 400, 418; M. Detienne et M. Rouland in Jour. de Phys., Vol. VII. for 1776; J. N. Hallé, “Exposition Abrégée,” etc. (“Bull. des Sc. de la Soc. Philom.,” An. X. No. 58); C. B. Désormes’ very extended observations recorded in the An. de Ch., Vol. XXXVII. p. 284; Volta’s letter to Prof. F. A. C. Gren in 1794, and Wilkinson, “El. of Galv.,” Vol. II. pp. 314–325; J. F. Ackerman (“Salz. Mediechirurg,” 1792, p. 287); Cadet (An. de Ch., Vol. XXXVII. p. 68); letter written by Volta to M. Dolomieu (“Bull. de la Société Philom.,” No. 55, p. 48); Friedlander’s “Experiments” (Jour. de Phys., Pluvoise, An. IX. p. 101); Paul Erman (Jour. de Phys., Thermidor, An. IX. p. 121); Gilbert’s “Annalen,” VIII, X, XI, XIV); Jour. de Phys., Tome LIII p. 309; Jour. de Médecine, Nivose, An. IX. p. 351; P. C. Abilgaard,“Tentamina Electrica”; C. H. Wilkinson, “Elements of Galvanism,” etc., London, 1804, 2 vols. passim; A. W. Von Hauch’s Memoir read before the Copenhagen Acad. of Sc. (Sue, “Hist. du Galv.,” 1802, Vol. II. p. 255); Alexander Nicoläus Scherer’s Journal, 31st book; “Abstracts of Papers of Roy. Soc.,” Vol. I. p. 27; also Hutton’s abridgments of the Phil. Trans. Vol. XV. p. 263; Vol. XVII. p. 285; Vol. XVIII. pp. 744, 798; Phil. Magazine, Vol. IV. pp. 59, 163, 306; “Bibliothèque Britannique,” Genève, 1796, Vol. XV. an. viii. p. 3; Vol. XIX for 1802, pp. 270, 274, 339; Vol. XVI, N.S. for 1821, pp. 270–309; account of the immense electrophorus constructed for the Empress of Russia, in Vol. I. of “Acta Petropolitana” for 1777, pp. 154, etc. In the Philosophical Transactions for 1778, pp. 1027, 1049, will be found Ingen-housz’s paper relating to the then recent invention of Volta’s electrophorus and to Mr. Henley’s experiments. It is said that at about this time (1778), John Jacob Mumenthaler, Swiss mechanic, constructed very effective electrophori and electric machines out of a very peculiar kind of paper. M. F. Vilette also made a paper electrophorus which is alluded to by J. A. Nollet (“Experiments Letters,” Vol. III. pp. 209, etc.). Consult, besides, Carlo Barletti, “Lettera al Volta ...” Milano, 1776; W. L. Krafft, “Tentatem theoriæ ...” Petropol, 1778; J. C. Schäffer, “Abbild. Beschr. d. elek. ...” Regensberg, 1778; Georg Pickel, “Experimenta physico-medica ...” Viceburgi, 1778–1788; J. A. Klindworth, “Kurze Beschr. ...” Gotha, 1781–1785; (Lichtenberg’s “Magazin,” I. 35–45;) while for Klindworth, M. Obert and M. Minkeler, see the “Goth. Mag.,” I. ii. p. 35; V. iii. pp. 96, 110; E. G. Robertson, “Sur l’électrophore résineux et papiracé,” Paris, 1790; (Journal de Physique, Vol. XXXVII;) M. Robert on the electrophorus (Rozier, XXXVII. p. 183); S. Woods, “Essay on the phenomena ...” London, 1805; (Phil. Mag., Vol. XXI. p. 289;) M. Eynard’s “Mém. sur l’electrophore,” Lyon, 1804; John Phillips, “On a modification of the electrophorus,” London, 1833 (Phil. Mag., s. 3, Vol. II); G. Zamboni, “Sulla teoria ...” Verona, 1844 (“Mem. Soc. Ital.,” Vol. XXIII); F. A. Petrina, “Neue theorie d. elect. ...” Prag., 1846.

=A.D. 1776.=--Borda (Jean Charles), French mathematician and astronomer, improves upon the work of Mallet (at A.D. 1769), and is the first to establish accurately the knowledge of the third and most important element of terrestrial magnetism, viz. its intensity.

To him is exclusively due the correct determination of the difference of the intensity at different points of the earth’s surface by measuring the vibrations of a vertical needle in the magnetic meridian. This he determined during his expedition to the Canary Islands, and his observations were first confirmed through additional experiments which the companion of the unfortunate La Pérouse, Paul de Lammanon, made during the years 1785–1787, and which were by him communicated from Macao to the Secretary of the French Academy.

REFERENCES.--Borda’s biography in the “Eng. Cycl.,” and in the eighth “Britannica”; Walker, “Magnetism,” p. 182; Humboldt on magnetic poles and magnetic intensity, embracing the observations of Admiral de Rossel, and “Cosmos,” Vol. V. 1859, pp. 58, 61–64, 87–100; also Vol. I. pp. 185–187, notes, for the history of the discovery of the law that the intensity of the force increases with the latitude; Norman (A.D. 1576).

=A.D. 1777.=--Lichtenberg (Georg Christoph), Professor of Experimental Philosophy at the University of Göttingen, reveals the condition of electrified surfaces by dusting them with powder.

The figures, which bear his name, are produced by tracing any desired lines upon a cake of resin with the knob of a Leyden jar and by dusting upon the cake a well-triturated mixture of sulphur and of red lead. These substances having been brought by friction into opposite electrical conditions, the sulphur collects upon the positive and the lead upon the negative portions of the cake: positive electricity producing an appearance resembling feathers, and negative electricity an arrangement more like stars.

REFERENCES.--Harris, “Frict. Elect.,” p. 89; eighth “Britannica,” Vol. VIII. p. 606; E. Reitlinger, “Sibven Abh. ...” (Wien Acad.); illustrations in Sc. Am. Suppl., No. 207, p. 3297; Noad, “Manual,” p. 132; Erxleben’s “Physikalische Bibliotek,” s. 514; L. F. F. Crell, Chemische Annalen for 1786; “Göttingisches Magazin,” J i., S ii., pp. 216–220; Lichtenberg’s “Math. u. Phys. Schriften,” etc., Vol. I. p. 478. See also Dr. Young’s “Lectures on Nat. Phil.,” London, 1807, Vol. II. pp. 119, 419 for additional references, and p. 426 for Lichtenberg’s “Table of Excitation.”

=A.D. 1777.=--Pringle (Sir John), a man of great scientific attainments--who was physician to the Duke of Cumberland as well as to the Queen’s household, became a baronet in 1766, and afterward received many distinguished honours from foreign learned bodies--resigns the Presidency of the English Royal Society, which he had held since the year 1772. In this, as will be seen at a later date, he was succeeded by Sir Joseph Banks (at A.D. 1820), who continued in the office a period of over forty-two years. The cause which led to his resignation is best given in the following extract from his biography in the English Cyclopedia:

“During the year 1777 a dispute arose among the members of the Royal Society relative to the form which should be given to electrical conductors so as to render them most efficacious in protecting buildings from the destructive effects of lightning. Franklin had previously recommended the use of points, and the propriety of this recommendation had been acknowledged and sanctioned by the Society at large. But, after the breaking out of the American Revolution, Franklin was no longer regarded by many of the members in any other light than an enemy of England, and, as such, it appears to have been repugnant to their feelings to act otherwise than in disparagement of his scientific discoveries. Among this number was their patron George III, who, according to a story current at the time, and of the substantial truth of which there is no doubt, on its being proposed to substitute knobs instead of points, requested that Sir John Pringle would likewise advocate their introduction. The latter hinted that the laws and operations of nature could not be reversed at royal pleasure; whereupon it was intimated to him that a President of the Royal Society entertaining such an opinion ought to resign, and he resigned accordingly.”

In Benjamin Franklin’s letter to Dr. Ingen-housz, dated Passy, Oct. 14, 1777, occurs the following: “The King’s changing his pointed conductors for blunt ones is therefore a matter of small importance to me. If I had a wish about it, it would be that he had rejected them altogether as ineffectual.” It was shortly after the occurrence above alluded to that the following epigram was written by a friend of Dr. Franklin:

“While you Great George, for knowledge hunt, And sharp conductors change for blunt, The nation’s out of joint: Franklin a wiser course pursues, And all your thunder useless views, By keeping to the point.”

Thomson informs us (“Hist. Roy. Soc.” pp. 446–447) that the Board of Ordnance having consulted the Royal Society about the best mode of securing the powder magazine, at Purfleet, from the effects of lightning, the Society appointed Mr. Cavendish, Dr. Watson, Dr. Franklin, Mr. Robertson and Mr. Wilson a committee to examine the building and report upon it. These gentlemen went accordingly, and the first four recommended the erecting of pointed conductors in particular parts of the building, as a means which they thought would afford complete security. Mr. Wilson dissented from the other gentlemen, being of the opinion that the conductors ought not to be pointed but blunt, because pointed conductors solicit and draw down the lightning which might otherwise pass by. He published a long paper on the subject, assigning a great variety of reasons for his preference (Philosophical Transactions, Vol. LXIII. p. 49). It was this dissent of Mr. Wilson which produced between the electricians of the Royal Society a controversy respecting the comparative merits of pointed and blunt conductors, which continued a number of years, and a variety of papers in support of which made their appearance in the Philosophical Transactions. The controversy, in fact, engaged almost the exclusive attention of the writers on electricity for several successive volumes of that work.

REFERENCES.--William Henley, “Experiments ... pointed and blunted rods ...” in Phil. Trans, for 1774, p. 133; P. D. Viegeron, “Mémoire sur la force des pointes ...”; Edward Nairne, “Experiments ... advantage of elevated pointed conductors,” in Phil. Trans. for 1778, p. 823; Lord Mahon, “Principles ... superior advantages of high and pointed conductors,” London, 1779; Hale’s “Franklin in France,” 1880, Part I. p. 91, and Part II. pp. 254–256, 279, for some of his other correspondence with Dr. Ingen-housz; likewise Part II., pp. ix, 273, 441–451, regarding the first publication of copies of letters written by Franklin to Sir Joseph Banks, which “for some curious reason,” Mr. Hale remarks, were not publicly read and were never included in the Philosophical Transactions, as Franklin intended they should be. Consult also Thomas Hopkinson on “The Effects of Points,” etc., in Franklin’s “New Experiments,” etc., London, 1754; Tilloch’s Philosophical Magazine for 1820; Hutton’s abridgments, Vol. XIII. p. 382; “Memoir of Sir J. Pringle” in Weld’s “Hist. of Roy. Soc.,” Vol. II. pp. 58–67, 102; Jared Sparks’ edition of Franklin’s “Works,” and Sir John Pringle’s discourse delivered at the Anniversary Meeting of the Royal Society, Nov. 30, 1774, a translation of the last named appearing at p. 15, Vol. XV of the “Scelta d’ Opuscoli.” J. Clerk Maxwell, “Electrical Researches of the Hon. Henry Cavendish,” 1879, pp. 52–54.

=A.D. 1778.=--Martin (Benjamin), English artist and mathematician, who had already written an “Essay on Electricity” and a prominent supplement thereto (1746–1748), publishes an enlarged edition in three volumes of his “Philosophia Britannica,” originally produced in 1759. At Vol. I. p. 47 of the last-named work, he states that his experiments indicate a magnetic force inversely as the square roots of the cubes of the distances. Noad, treating of the laws of magnetic force, says (“Electricity” p. 579) that Martin and Tobias Mayer both came to the conclusion that the true law of the magnetic force is identical with that of gravitation, and that, in the previous experiments of Hauksbee and others, proper allowance had not been made for the disturbing changes in the magnetic forces so inseparable from the nature of the experiments.

His first Lecture explains all the phenomena of electricity and magnetism, the appendix thereto detailing numerous experiments of Mr. John Canton, and giving many additional facts concerning the manufacture of artificial magnets. From his preface the following extracts will, doubtless, prove interesting: “We are arrived at great dexterity since Sir Isaac Newton’s time; for we can now almost prove the existence of this aether by the phenomena of electricity; and then we find it very easy to prove that electricity is nothing but this very aether condensed and made to shine. But I believe, when we inquire into the nature and properties of this aether and electricity, we shall find them so very different and dissimilar, that we cannot easily conceive how they should thus mutually prove each other.... I see no cause to believe that the matter of electricity is anything like the idea we ought to have of the spiritus subtilissimus of Sir Isaac.... The smell also of electrical fire is so very much like that of phosphorus, that we may be easily induced to believe a great part of the composition of both is the same.”

REFERENCES.--“Encycl. Britan.,” 1857, Vol. XIV. p. 320; Antoine Rivoire (Rivière), “Traité sur les aimants ...” Paris, 1752; Nicolaus von Fuss, “Observations ... aimants ...” Petersburg, 1778; Le Noble, “Aimants artificiels ...” Paris, 1772, and “Rapport ... aimants,” 1783 (Mém. de Paris); Wens, “Act. Hill,” Vol. II. p. 264; C. G. Sjoestén (Gilbert, Annalen der Physik, Vol. XVII. p. 325); Rozier, IX. p. 454.

=A.D. 1778.=--Toaldo (Giuseppe) Abbé, celebrated Italian physicist, who had in 1762 been made Professor at the Padua University and was the first one to introduce the lightning rod in the Venetian States, makes known the merits of the last-named invention through his “Dei conduttori per preservare gli edifizj,” etc., which work embraces most of his previous treatises on metallic conductors as well as the translation of H. B. de Saussure’s “Exposition abrégée,” etc., Geneva, 1771, and of M. Barbier de Tinan’s “Considérations sur les conducteurs en général.”

The above was followed by many highly interesting memoirs containing valuable meteorological observations, notably those in continuation of the work of J. Poleni, made close up to the time of Toaldo’s sudden death at Padua, Dec. 11, 1798. His complete works, covering the period 1773–1798, were published in Venice through M. Tiato, with the assistance of Vincenzo Chiminello, during the year 1802.

REFERENCES.--In addition to the last-named publication (entitled “Completa Raccolta d’ Opuscoli,” etc.), “Mem. della Soc. Ital.,” Vol. VIII. pt. i. p. 29 (“Elogio ... da A. Fabbroni,” 1799); note at Beccaria, p. 42 of Ronalds’ “Catalogue”; Larousse, “Dict. Universel,” Vol. XV. p. 251; “Biographie Générale,” Vol. XLV. p. 450; “Biografia degli Italiani Illustri,” etc., by E. A. Tipaldo, Vol. VIII; “Padua Accad. Saggi,” Vol. III. p. cv; “Opusc. Scelti,” Vol. VI. p. 265; Vol. VII. p. 35; “Nuovo Giornale Enciclopedico di Vicenza” for 1784; Antonio Maria Lorgna, “Lettera ... parafulmini,” 1778; G. Marzari (Vol. II. p. 73, of “Treviso Athenæum”); Fonda “Sopra la maniera ...” Roma, 1770; G. Marzari e G. Toaldo, “Memoria Descrizione ...” 25 Aprile, 1786; Barbier de Tinan, “Mémoire sur la manière d’armer,” etc., Strasbourg, 1780; F. Maggiotto’s letter to Toaldo upon a new electrical machine; Sestier et Méhu, “De la foudre,” etc., Paris, 1866.

Vincenzo Chiminello, nephew of Giuseppe Toaldo, whom he succeeded at the Padua Observatory and who continued the Giornale Astro-meteorologico after his uncle’s death, is the author of works on the magnetic needle, on lightning conductors, etc., which are treated of in the columns of the Mem. Soc. Ital., Vols. VII and IX; the Giornale Astro-met. for 1801, 1804, 1806, as well as in the Saggi ... dell’Accad. di Padova, Nuova Scelta d’Opuscoli, and Opuscoli Scelti sulle scienze e sulle arti.

REFERENCES.--Chiminello’s biography, _Giorn. dell’Ital. Lettera_, etc., Serie II. tome xvii. p. 164, and in “Atti della Soc. Ital.,” Modena, 1819.

=A.D. 1778.=--Dupuis (Charles François), eminent French writer who, at the age of twenty-four, became Professor of Rhetoric at the College of Lisieux, constructs a telegraph upon the plan suggested by Amontons (at A.D. 1704). By means of this apparatus he exchanged correspondence with his friend M. Fortin, then residing at Bagneux, until the commencement of the Revolution, when he deemed it prudent to lay it permanently aside (Encyclopædia Britannica, 1855, Vol. VIII. p. 263).

=A.D. 1778.=--Brugmans--Brugman (Anton), who was Professor of Philosophy at the University of Francker between 1755 and 1766, publishes his “Magnetismus, seu de affinitatibus magneticis.” He is, besides, the author of several works upon magnetic matter and the magnetic influence, which appeared 1765–1784 and are alluded to by Poggendorff (“Biog.-Liter. Hand.,” Vol. I. p. 316), as well as in the “Vaderlandsche Letter” for 1775 and 1776, and at p. 34, Vol. I of Van Swinden’s “Recueil de Mémoires ...” La Haye, 1784.

It was in this same year, 1778, that Sebald Justin Brugmans--Brugman--son of Anton Brugmans, a distinguished physician, naturalist and author who was the successor of Van Swinden at the Francker University, and became Professor of Botany at Leyden, discovered that cobalt is attracted while bismuth and antimony are repelled by the single pole of a magnet, thus laying the foundation of the science of diamagnetism.

Humboldt remarks: “Brugmans, and, after him, Coulomb, who was endowed with higher mathematical powers, entered profoundly into the nature of terrestrial magnetism. Their ingenious physical experiments embraced the magnetic attraction of all matter, the local distribution of force in a magnetic rod of a given form, and the law of its action at a distance. In order to obtain accurate results the vibrations of a horizontal needle suspended by a thread, as well as deflections by a torsion balance, were in turn employed.”

REFERENCES.--“Biographie Générale,” Vol. VII. p. 582; Larousse, “Dict. Univ.,” Vol. II. p. 1334; “Catalogue Sc. Papers Roy. Soc.,” Vol. I. p. 672; W. H. Wollaston, “Magnetism of ... Cobalt and Nickel” (Edin. Phil. Jour., Vol. X. p. 183); Kohl on pure cobalt (L. F. F. Crell’s “Neusten Ent.,” Vol. VII. p. 39); Tyndall, “Researches on Dia-Magnetism,” London, 1870, pp. 1, 90, etc.; Appleton’s Encyclopædia, 1870, Vol. IV. p. 10; Humboldt’s “Cosmos,” 1859, Vol. V. p. 61; Augustin Roux, “Expériences nouvelles ...” (Journal de Médecine, for November 1773). Consult also, for Sebald J. Brugmans, “Biog. Générale,” Vol. VII. p. 582; Bory de Saint Vincent, in the “Annales Générales de Sciences Physiques,” Vol. II.

=A.D. 1779.=--Lord Mahon, afterward third Earl of Stanhope, an Englishman of great ingenuity and fertility in invention and a pupil of Lesage of Geneva (at A.D. 1774), publishes his “Principles of Electricity,” in which he explains the effects of the return stroke or lateral shock of an electrical discharge which was first observed by Benjamin Wilson (at A.D. 1746).

He imagined that when a large cloud is charged with electricity it displaces much of that fluid from the neighbouring stratum of air, and that when the cloud is discharged the electric matter returns into that portion of the atmosphere whence it had previously been taken. According to Lord Cavendish, the theory developed in the above-named work is that “A positively electrified body surrounded by air will deposit upon all the particles of that air, which shall come successively into contact with it, a proportional part of its superabundant electricity. By which means, the air surrounding the body will also become positively electrified; that is to say, it will form round that positive body an electrical atmosphere, which will likewise be positive.... That the Density of all such atmospheres decreases when the distance from the charged body is increased.”

Tyndall says (Notes on Lecture VII) that Lord Mahon fused metals and produced strong physiological effects by the return stroke.

In 1781, the English scientist, John Turberville Needham (1713–1781), published at Brussels his French translation of Lord Mahon’s work under the title of “Principes de l’Electricité.” Needham was the first of the Catholic clergy elected to a fellowship of the English Royal Society, to whose Transactions he made several contributions. His numerous works include “A letter from Paris concerning some new electrical experiments made there,” London, 1746, also a volume of researches upon the investigations of Spallanzani. The list of his communications to the Phil. Trans. and to the “Mém. de l’Acad. de Bruxelles” will be found in Watt’s “Bibliotheca Britannica” and in Namur’s “Bibl. Acad. Belge” (“Dict. Nat. Biog.,” Vol. XL. p. 157; Phil. Trans., 1746, p. 247, and Hutton’s abridgments, Vol. IX. p. 263).

REFERENCES.--“Electrical Researches” of Lord Cavendish, pp. xlvi-xlvii; Phil. Trans. for 1787, Vol. LXXVII. p. 130; Dr. Thomas Young, “Course of Lectures,” London, 1807, Vol. I. p. 664; Dr. Thomas Thomson, “History of the Royal Society,” London, 1812, p. 449; Sturgeon, “Researches,” Bury, 1850, p. 398.

=A.D. 1779.=--Ingen-housz (Johan), distinguished English physician and natural philosopher, native of Breda, publishes, Phil. Trans., p. 661, an account of the electrical apparatus which is by many believed to have led to the invention of the plate electrical machine, although the same claim has been made in behalf of Jesse Ramsden (at A.D. 1768). Dr. Priestley states that Ingen-housz and Ramsden invented it independently of one another. He describes a circular plate of glass nine inches in diameter turning vertically and rubbing against four cushions, each an inch and a half long and placed at the opposite ends of the vertical diameter. The conductor is a brass tube bearing two horizontal branches extending to within about half an inch of the extremity of the glass, so that each branch takes off the electricity excited by two of the cushions (Dr. Thomas Young, “Course of Lectures,” Vol. II. p. 432).

The plate machine of Dr. Ingen-housz is illustrated at p. 16 of “Electricity” in the “Library of Useful Knowledge.” For other plate machines see, more particularly, Dr. Young’s “Course of Lectures,” Vol. II. p. 431; Phil. Trans. 1769, p. 659; Geo. K. Winter’s apparatus with ring conductor and peculiar-shaped rubbers, as well as the great machine at the Royal Polytechnic, and that of Mr. Snow Harris, illustrated and described in Vol. III. p. 787, “Eng. Ency.--Arts and Sciences,” and at pp. 223, 224 of J. H. Pepper’s “Cyclopædic Science,” London, 1869; “Allg. deutsche Biblioth.,” B. XXIV. Anh. 4, Abth., p. 549, 1760 (Poggendorff, Vol. II. p. 465), relative to the machines of Martin Planta, Ingen-housz and Ramsden; Reiser’s plate machine (Lichtenberg and Voigt’s “Magazin für das Neueste aus der Physik,” Vol. VII. St. 3, p. 73); Ferdinando Elice, “Saggio sull’Elettricita,” Genoa, 1824 (for two electricities); J. J. Metzger’s machine (Elice, “Saggio,” second edition, p. 55); Marchese C. Ridolfi, for a description of Novelluccis’ plate electrical machine (“Bibl. Italiana,” Vol. LXIII. p. 268; “Antologia di Firenze,” for August 1824, p. 159); Robert Hare, “Description of an Electrical Plate Machine,” London, 1823 (Phil. Mag., Vol. LXII. p. 8). See, besides, the machines of Bertholon (rubber in motion) in Lichtenberg and Voigt’s “Magazin,” Vol. I. p. 92 and Rozier XVI. p. 74; of Brilhac (Rozier, XV. p. 377); of Saint Julien (Rozier, XXXIII. p. 367); of Van Marum (Rozier, XXXVIII. p. 447).

Dr. Ingen-housz also constructed a small magnet, of several laminæ of magnetised steel firmly pressed together, capable of sustaining one hundred and fifty times its own weight, and he found that pastes into the composition of which the powder of the natural magnet entered were much superior to those made with the powder of iron; the natural magnet, he observed, having more coercitive force than iron.

REFERENCES.--Journal de Physique for February 1786, and for May 1788, containing the letters of Dr. Ingen-housz, which show that the vegetation of plants is in no sensible degree either promoted or retarded by common electricity. An account is also given of his experiments in “Versuche mit Plantzen,” Vienna, 1778, in the “Catalogue of the Royal Society,” p. 313, in “Goth. Mag.,” Vol. V. iii. 13; Rozier, XXXII. p. 321; XXXIV. p. 436; XXXV. p. 81; Journal de Physique, Vol. XXXV for 1789. See also, Journal de Physique, XLV (II), 458; Rozier, XXVIII. p. 81; M. Nuneberg, “Osservazioni ...” Milano, 1776 (“Scelta d’Opuscoli,” XVII. p. 113); Pietro Moscati, “Lettera ...” Milano, 1781 (“Opus Scelti,” IV. p. 410); H. B. de Saussure (Journal de Physique, Vol. XXV for 1784); G. da San Martino, “Memoria ...” Vicenza, 1785; M. Schwenkenhardt, “Von dem Einfluss ...” (Rozier, XXVII. p. 462; Journal de Physique for 1786, Vol. I); A. M. Vassalli-Eandi in the “Mem. della Soc. Agr. di Torino,” Vol. I for 1786, particularly regarding the experiments of Ingen-housz and Schwenkenhardt; also in the “Giornale Sc. d’una Soc. Fil. di Torino,” Vol. III; N. Rouland, “Elec. appliquée aux vegétaux” (Journal de Physique, 1789–1790); Ingen-housz, Rouland, Dormoy, Bertholon and Derozières (Rozier, XXXV. pp. 3, 161, 401; XXXVIII. pp. 351, 427, and in Journal de Physique, Vols. XXXII, XXXV, XXXVIII); M. Carmoy, on the effects of electricity upon vegetation, in Rozier, XXXIII. p. 339; Jour. de Physique 1788, Vol. XXXIII; M. Féburier, “Mémoire sur quelques propriétés ...”; G. R. Treviranus, “Einfluss ...” Kiel, 1800 (Gilbert’s Annalen, Vol. VII for 1801 and “Nordisches Arch. f. Nat. u. Arzneiw.,” 1st Band, 2tes Stück); C. G. Rafn (“Mag. Encyclopédique,” No. 19, Ventose An. X. p. 370), Paris, 1802; J. P. Gasc, “Mémoire sur l’influence ...” Paris, 1823; E. Solly, “On the influence ...” London, 1845 (“Journ. of the Hortic. Society,” Vol. I. part ii.); E. Romershausen, “Galv. El. ... Vegetation,” Marburg, 1851; M. Menon, “Influence de l’électricité sur la végétation,” and his letters to R. A. F. de Réaumur. Consult likewise J. Browning’s letter to H. Baker, Dec. 11, 1746 (Phil. Trans. for 1747, Vol. XLIV. p. 373); G. Wallerius, “Versuch ...” Hamb. and Leipzig, 1754; (“K. Schwed. Akad. Abh.,” XVI. p. 257; also “Vetensk Acad. Handl.,” 1754;) L. F. Kamtz (Kaemtz), “Über d. Elek ...” Nürnberg, 1829; (Schweigger’s Journal f. Chemie u. Physik, Vol. LVI;) Bartolomeo Zanon, “Intorno un punto ...” Belluno, 1840; Francesco Zantedeschi “Dell influsso ...” Venezia, 1843; (“Mem. dell Instit. Veneto,” I. p. 269;) E. F. Wartmann, “Note sur les courants ...” Genève, 1850; (“Bibl. Univ. de Genève,” for Dec. 1850;) T. Pine, “Connection between Electricity and Vegetation,” London, 1840; (“Annals of Electricity,” Vol. IV. p. 421.) For the effects of galvanism on plants, see Giulio in “Bibl. Ital.,” Vol. I. p. 28; also E. J. Schmuck “On the Action of Galvanic Electricity on the Mimosa Pudica,” and M. Rinklake, as well as Johann W. Ritter, “Elektrische versuche an der Mimosa Pudica.” For an account of M. P. Poggioli’s observations on the influence of the magnetic rays on vegetation, and the reply of F. Orioli thereto, see Vol. I of the “Nuova collezione d’opuscoli scientifici ...” Bologna, 1817. Dr. Thomas Young’s “Course of Lectures,” Vol. II. pp. 432–433; N. K. Molitor’s “John Ingen-housz. Anfangsgrunde ...” 1781; Geo. Adams, “Lectures on Nat. and Exp. Philosophy,” London, 1799, Vol. I. pp. 512–515; John Senebier, “Expériences,” etc., 1st and 2nd Memoirs, Genève and Paris, 1788; Becquerel in the Comptes Rendus for November 1850, also Tome XXXI. p. 633; M. Buff (Phil. Mag. N. S. Vol. VII. p. 122); Priestley’s “History ...” 1775, p. 487; Walsh at A.D. 1773; Cavallo’s “Exper. Philosophy,” 1803, Vol. III. p. 357; Pouillet (Poggendorff’s Annalen, Vol. XI. p. 430); Reiss, in Poggendorff’s Annalen, Vol. LXXIX. p. 288; G. F. Gardini, “De inflvxu ...” s. 7, p. 10; Philosophical Transactions for 1775, 1778, p. 1022; 1779, p. 537; Journal de Physique, Vol. XVI for 1780; “Erxleben’s phys. bibliothek,” s. 530; papers relative to the effects of electricity upon vegetation alluded to in “Le Moniteur Scientifique,” more particularly at pp. 904, 907, 1026, Vol. XX for 1878, and at p. 23, Vol. XXI for 1879.

=A.D. 1780.=--Spallanzani (Lazaro), celebrated Italian naturalist, to whom the French Republic vainly offered the Professorship of Natural History at the Paris Jardin des Plantes, and who has been already particularly alluded to in connection with John Walsh, at A.D. 1773, writes a second treatise upon the operations of Charles Bonnet, of Geneva, as regards the effects of electricity upon nerves and muscles. He is also the author of works upon electrical fishes as well as upon meteors, etc., which will be found detailed in Vol. VII of the “Biographie Médicale,” as well as at Vol. XLIII. p. 246, of the “Biographie Universelle.”

REFERENCES.--Alibert’s Eloge in Vol. III of the “Mém. de la Soc. Médicale d’Emulation”; “Catal. Roy. Soc. Sc. Papers,” Vol. V. p. 767; “Opus. Scelti,” Vols. VII. pp. 340, 361; VIII. p. 3; XIV. pp. 145, 296; Brugnatelli, “Ann. di chimica” for 1793 and 1795; “Mem. Soc. Ital.,” Vols. II. p. 11; IV. p. 476.

=A.D. 1780–1781.=--Bertholon de Saint Lazare (Pierre), French physician and Professor of Natural Philosophy, and a great friend of Dr. Franklin, publishes at Paris his “Electricité du Corps Humain ...” in which he relates more particularly his general observations upon atmospheric electricity as affecting the human body while in a healthy state and while in a diseased condition. He likewise treats of the effects of electricity upon animals, and details very interesting experiments upon the torpedo, which latter, he remarks, establishes the closest possible resemblance to the Leyden phial.

He is also the author of “Electricité des Végétaux” (1783), as well as of “Electricité des Météores” (1787), and of a volume entitled “Electricité des Métaux.” J. C. Poggendorff says (“Biog.-Lit. Handw. ...” Vol. II. p. 102) that J. Ferd. Meidinger (1726–1777) had previously written concerning the action of electric fire upon metals and minerals. Johann Jacob Hemmer published, at Mannheim in 1780, “Sur l’Electricité des Métaux” (“Ob. sur la Physique,” July 1780, p. 50), and A. A. De La Rive wrote in 1853 “De l’Elect. Développée ...” (“Bibl. Univ.,” Vol. LIX).

REFERENCES.--Young’s “Course of Lectures,” Vol. II. p. 431; Ingen-housz at A.D. 1779; Journal de Physique, Vol. XXXV; “Biographie Universelle,” Vol. IV. p. 149; “Biographie Générale,” Vol. V. p. 722; Larousse, “Dict. Univ.,” Vol. II. p. 618; “La Grande Encyclopédie,” Vol. VI. p. 450. See also Bertholon’s “Nouvelles Preuves ...” pp. 18–19; Arago, “Notices Scientifiques,” Vol. I. pp. 338–340, 386; “Mercure de France,” 1782, No. 52, p. 188; Abbé d’Everlange de Wittry, “Mém. sur l’Elec. ... dans les végétaux et le corps humain,” read June 24, 1773--“Anc. Mém. de l’Acad. Belge,” Vol. I. p. 181; Vassalli-Eandi, “Esame della Elett. delle Meteore del Bertholon,” Torino, 1787; account of the experiments to ascertain the effects of electricity on vegetation, made in France during the summer of 1878 by MM. Grandeau, Celi and Leclerc; and a curious publication, “Les Animaux et les Métaux deviennent ils Electriques par communication,” by L. Béraud (Bérault), alluded to in Poggendorff, Vol. I. p. 146.

=A.D. 1780–1783.=--Prof. Samuel Williams, at Cambridge, Mass., makes the earliest known observations of the magnetic dip in the United States, and publishes them in the “Memoirs of the American Academy of Arts,” Vol. I. pp. 62, 68. According to this authority, the dip in 1783 was 69° 41’. The next dip observations are those made during Long’s expedition to the Rocky Mountains in 1819.

REFERENCES.--“American Journal of Science,” Vol. XLIII. pp. 93, 94; “Trans. Amer. Phil. Soc.,” O. S., Vol. III. p. 115.

=A.D. 1780–1794.=--Le Père Amyot (Amiot), learned French Jesuit, who was sent in 1751 as a missionary to Pekin, where he resided till his decease in 1794, writes, on the 26th of July 1780, and also on the 20th of October 1782 that, as a result of a great number of observations, he finds no change in the variation of the magnetic needle, i. e. that “the point which indicates the north declines westerly from 2 to 2½ degrees, rarely more than 4½ degrees, and never less than 2 degrees.”

REFERENCES.--“Mémoires concernant l’histoire,” etc., Saillant et Nyon, Vol. X. p. 142; Davis, “The Chinese,” Vol. III. p. 13.

=A.D. 1781.=--The so-called compass plant (Silphium lancinatum) is first introduced from America into Europe by M. Thouin and blooms for the first time in the Botanic Gardens of Upsala, Sweden.

In the “Scientific American” of February 26, 1881, reference is made to the interesting account of this plant given by Sir J. D. Hooker in Curtis’ “Botanical Magazine,” as well as to the following extract from Prof. Asa Gray’s report concerning it: “The first announcement of the tendency of the leaves of the compass plant to direct their edges to the north and south was made by General (then Lieutenant) Alvord, of the U.S. Army, during the year 1842, and again in 1844, in communications to the American Association for the Advancement of Science.... The lines in “Evangeline” (familiar to many readers):

“Look at this delicate plant that lifts its head from the meadow, See how its leaves all point to the north as true as the magnet; It is the compass plant that the finger of God has suspended, Here on its fragile stalk, to direct the traveller’s journey, Over the sealike, pathless, limitless waste of the desert----”

were inspired through a personal communication made by General Alvord to the poet Longfellow.

In this connection, the following article, headed “A Wonderful Magnetic Plant,” translated from La Nature by the London Court Journal, will prove interesting: “There has been discovered in the forests of India a strange plant (Philotacea electrica) which possesses to a very high degree astonishing magnetic power. The hand which breaks a leaf from it receives immediately a shock equal to that which is produced by the conductor of an induction coil. At a distance of six metres a magnetic needle is affected by it, and it will be quite deranged if brought near. The energy of this singular influence varies with the hours of the day. All powerful about two o’clock in the afternoon, it is absolutely annulled during the night. At times of storm its intensity augments to striking proportions. While it rains the plant seems to succumb: it bends its head during a thunder-shower and remains without force or virtue even if one should shelter it with an umbrella. No shock is felt at that time in breaking the leaves, and the needle is unaffected by it. One never by any chance sees a bird or insect alight on this electric plant; an instinct seems to warn them that in so doing they would find sudden death. It is also important to remark that where it grows none of the magnetic metals are found, neither iron, nor cobalt, nor nickel--an undeniable proof that the electric force belongs exclusively to the plant. Light and heat, phosphorescence, magnetism, electricity, how many mysteries and botanical problems does this wondrous Indian plant conceal within its leaf and flower!”

The results of some interesting researches on plant-electricity have been reported by A. D. Waller, who finds that whenever a plant is wounded, a positive electric current is established between the wounded part and the intact parts. This may start with an electromotive force of 0·1 volt, but it afterward diminishes. He writes further:

“Actual wounding is not necessary to obtain this manifestation; an electro-positive current is set up when there is mechanical excitation, but it is much weaker (0·02 volt). And light acts like mechanical excitation with certain plants, such as the leaves of the iris, of tobacco, of the begonia, etc. From the illuminated to the darkened part flows a positive electric current that may be as strong as 0·02 volt. A similar reaction in the petals is not always observed. There is a certain correlation between the vigour of a plant and the electric reaction. The more vigorous the plant is, the stronger the current. Plants grown from fresh seeds give a more powerful current than those from old seeds. A bean a year old gave a current of 0·0170 volt; one five years old, a current of 0·0014; and the reaction is inversely and regularly proportional to the age of the seed from which the plant springs. There is observed in vegetable tissues, subjected to an excitation of the same intensity at regular intervals, the characteristic changes of reaction that are present in animal tissues--fatigue, recuperation, etc. Temperature plays a part in all these phenomena; below -4° to -6° C. [+° to + 25° F.] and above 40° C. [108° F.] there is no reaction.”

=A.D. 1781.=--Lavoisier (Antoine Laurent), an eminent French natural philosopher, the chief founder of modern chemistry as well as of the prevailing system of chemical nomenclature which ended in the expulsion of the phlogistic theory, demonstrates by experiments made in conjunction with Volta and Laplace that electricity is developed when solid or fluid bodies pass into the gaseous state. Sir David Brewster says that the bodies to be evaporated or dissolved were placed upon an insulating stand and were made to communicate by a chain or wire with a Cavallo electrometer, or with Volta’s condenser, when it was suspected that the electricity increased gradually. When sulphuric acid, diluted with three parts of water, was poured upon iron filings, inflammable air was disengaged with a brisk effervescence; and, at the end of a few minutes, the condenser was so highly charged as to yield a strong spark of negative electricity. Similar results were obtained when charcoal was burnt on a chafing dish, or when fixed air or nitrous gas was generated from powdered chalk by means of the sulphuric and nitrous acids.

The phlogistic theory alluded to above, which was so named by George Ernest Stahl in 1697 after Johann Joachim Beccher (1635–1682) had pointed out its principle in 1669, had for its most energetic defender the editor of the Journal de Physique, M. J. C. De La Méthérie, who is entered at A.D. 1785, and it was in order to offset the influence which this gave him that the antiphlogistians established the Annales de Chimie, so frequently mentioned in these pages.[52]

REFERENCES.--George Adams’ “Lectures on Nat. and Exp. Philosophy,” London, 1799, Vol. I. pp. 575–587, wherein Lavoisier’s system is confuted by the German chemist Wieglib, whose views are endorsed by Mr. Green, while for Stahl and Beccher, refer to Sir H. Davy, “Bakerian Lectures,” London, 1840, p. 102, note, to “Biog. Gén.,” Vol. V. pp. 85–87; “Meyer’s Konvers. Lexikon,” Vol. II. p. 654, and to Thomson’s “Hist. of Roy. Soc.,” London, 1812, p. 467. See also J. M. G. Beseke, “Ueber elementärfeuer ...” Leipzig, 1786; G. A. Kohlreif, “Sollte die elektricität ...” Weimar, 1787; Lavoisier and Laplace, in the “Mém. de l’Acad. Roy. des Sciences” for 1781, p. 292; Lavoisier’s “Opuscules ...” 1774, and his “Rapport ... mag. animal.,” Paris, 1784; Dr. Thomas Thomson, “Hist. Roy. Soc.,” pp. 479–486; Herschel’s “Nat. Phil.,” concerning the third age of chemistry; Grégoire, “Dict. d’hist.,” etc., p. 1171; Miller’s “Hist. Phil. Illus.,” London, 1849, Vol. IV. pp. 332–333, notes. Chap. IV of the “History of Chemistry,” Ernst Van Meyer, tr. by George McGowan, London, 1898, entitled “History of the Period of the Phlogiston Theory from Boyle to Lavoisier,” will prove interesting. “La chimie constituée par Lavoisier,” Jacob Volhard, in “Le Moniteur Scientifique,” du Dr. Quesneville, Vol. XIV for 1872, pp. 50–71; “Nouveau Larousse,” Vol. V. p. 608; “La Révolution chimique,” M. Berthelot, Paris, 1890; “Essays in Historical Chemistry,” T. E. Thorpe, London, 1894, pp. 87, 110; “Journal des Savants” for Nov. 1859 and Feb. 1890; “Lives of Men of Letters and Science,” by Henry, Lord Brougham, Philadelphia, 1846, pp. 140–166.

=A.D. 1781.=--Achard (Franz Carl), able chemist and experimental philosopher, born in Prussia but of French extraction, communicates to the “Mém. de Berlin” a report of many very interesting experiments made by him, which are reviewed by Prince Dmitri Alexewitsch Fürst Gallitzin, in Vol. XXII of the Journal de Physique.

He had previously published essays upon the electricity of ice and the electricity developed on the surface of bodies, as well as upon terrestrial magnetism, the electrophorus, etc. He made many notable investigations to prove that fermentation is checked by electricity and that putrefaction is hastened both in electrified meats and in animals killed by the electric shock.

One of his experiments illustrating galvanic irritation so greatly interested Humboldt that the latter repeated it with different animals, not doubting but small birds might in many cases be brought back to life when they fall into a state somewhat resembling death. On one occasion, he took a linnet about to expire and, having established the necessary communication, perceived, the moment the contact took place, that the linnet opened its eyes, stood erect upon its feet and fluttered its wings; it breathed, he says, during six or eight minutes and then expired tranquilly.

It was a namesake of Achard who invented the electro-magnetic brake which will be found described and illustrated in articles from the London Engineer and Engineering, reproduced through the Scientific American Supplements, No. 111, p. 1760, and No. 312, p. 4974.

REFERENCES.--Poggendorff, “Biog.-Lit. Hand. ...” Vol. I. p. 7; “Biographie Générale,” Vol. I. p. 176; “Cat. Roy. Soc. Sc. Papers,” Vol. I. p. 9; “Opus. Scelt.,” Vols. III. p. 313; V. p. 351; VI. p. 199; Reuss, Repertorium, Vol. IV. p. 351; Dr. G. Gregory, “Economy of Nature,” London, 1804, Vol. I. p. 317; Van Swinden, “Recueil ...” La Haye, 1784, Vol. I. p. 24; “Biographie Universelle,” Vol. I. p. 114; “Journal Lit. de Berlin,” for 1776; Cavallo, London, 1777, p. 403; “Mém. de Berlin” for 1776–1780, 1786, 1790–1791; Sturgeon, “Lectures,” London, 1842, p. 12; Geo. Adams, “Essay on Electricity,” etc., London, 1785, pp. 214–220, 277; “Gött. Mag.,” Vol. II. ii. 139; Rozier, VIII. p. 364; XV. p. 117; XIX. p. 417; XXII. p. 245; XXIII. p. 282; XXV. p. 429; XXVI. p. 378; Phil. Mag., Vol. III. p. 51.

=A.D. 1781.=--Kirwan (Richard), LL.D., F.R.S., an Irish chemical philosopher of great eminence, who became President of the Dublin Society and of the Royal Irish Academy, receives from the English Royal Society its gold Copley medal for the many valuable scientific papers communicated by him to the latter body. These papers embrace his “Thoughts on Magnetism,” wherein he treats at length of attraction, repulsion, polarity, etc., as shown in the review given at pp. 346–353 of the eighth volume of Sturgeon’s “Annals of Electricity,” etc.

It is said that Kirwan first suggested the notion of molecular magnets, but, according to Dr. J. G. M’Kendrick, it was not till a definite form was given thereto by Weber that it acquired any importance.

REFERENCES.--Transactions Royal Irish Academy, Vol. VI; Ninth “Encycl. Britannica,” Vol. XV. p. 276; Phil. Mag., Vol. XXXIV. p. 247; Thomson, “Hist. of the Roy. Soc.,” p. 483; “Bibl. Britan.,” An. VII. vol. xii. p. 105.

=A.D. 1781.=--Mauduyt (Antoine René) (1731–1815), Professor at the Collège de France, publishes several observations from which he concludes that the application of electricity is favourable in cases of paralysis. He was in the habit of placing the patient upon an insulated stool, in communication with the conductor of an electrical machine. De La Rive, who mentions the fact (“Electricity,” Chap. III. pp. 586, 587), observes that the effect, if any, could only proceed from the escape of electricity into the air.

REFERENCES.--Bertholon, Elec. du Corps. Humain, 1786, Vol. I. pp. 275–276, 302, 439, 447, etc., and Vol. II. pp. 7 and 296; “Mémoire sur les différentes manières d’administrer l’électricité,” etc., Paris, 1784; “Recueil sur l’électricité médicale,” etc., containing articles by G. F. Bianchini, De Lassoné, Deshais (see Sauvages), Dufay, Jallabert, Pivati, Quellmalz, Veratti, Zetzell, etc.; K. G. Kuhn’s works published at Leipzig, 1783–1797; E. Ducretet in “Le Cosmos,” Paris, Oct. 3, 1891, pp. 269–272; P. Sue, aîné, “Hist. du Galvan,” Paris, An. X-XIII, 1802, Vol. I. p. 40; and Vol. II. p. 382; “Grande Encyclop.,” Vol. XXIII. p. 415.

=A.D. 1781–1783.=--Don Gauthey--Gauthier or Gualtier--a monk of the Order of Citeaux, improved upon the invention of Dupuis (at A.D. 1778) and constructed a telegraph, which he submitted at the Académie des Sciences to Dr. Franklin as well as to Condorcet and De Milly, by whom it was recommended to the French Government. In his prospectus, published during 1783, he relates that he has discovered a new mode of rapid transmission enabling him to convey intelligence and sound, by means of water pipes, a distance of fifty leagues in fifty minutes. Ternant, who states this at pp. 33 and 34 of Le Télégraphe, Paris, 1881, adds that, as no action was taken at the time upon the prospectus, it doubtless still lies in the archives of the Academy.

REFERENCES.--Laurencin, Le Télégraphe, p. 9; Eng. Cycl., “Arts and Sciences,” Vol. VIII. p. 65; “Penny Cycl.,” 1842, Vol. IV. p. 146.

=A.D. 1782.=--Nairne (Edward), an English mathematical instrument maker, publishes papers on electricity describing his invention of a cylinder machine which is illustrated and described at p. 15 of the chapter on “Electricity” in “Library of Useful Knowledge,” 1829. In this, as has been truly said, are seen all the essential parts of the frictional apparatus now in use.

This machine, according to Cuthbertson, was originally constructed in 1774, and was far more powerful than any before made. Nairne also constructed the largest battery known up to that time. It contained 50 square feet of coated surface, and it could be given so high a charge as to ignite 45 inches of iron wire ¹⁄₁₅₀ of an inch diameter, which up to that period was the greatest length of wire ever ignited. Nairne, while improving upon some of Priestley’s experiments, found that a piece of hard drawn iron wire, ten inches long and one-hundredth of an inch diameter, after receiving successively the discharge of 26 feet of coated glass (nine jars), was shortened three-fortieths of an inch by such discharge. Dr. Priestley had previously observed that a chain 28 inches long was shortened one quarter of an inch after having had transmitted through it a charge of 64 square feet of coated glass, and Brooke Taylor found that by passing a charge of nine bottles of 16 feet of coated surface nine times in succession through a steel wire 12 inches long and one one-hundredth of an inch diameter, the wire was shortened one and one-half inches, or one-eighth its entire length.

To Nairne was granted the third English patent in the Class of Electricity and Magnetism, the first having been issued to Gowin Knight in 1766 (see A.D. 1746) and the second to Gabriel Wright, June 25, 1779, for “a new constructed azimuth and amplitude compass.” Knight subsequently covered other similar inventions, July 5, 1791, and Jan. 19, 1796. Nairne’s patent bears date Feb. 5, 1782, No. 1318, and is for what he calls “The Insulated Medical Electrical Machine,” the conductors of which are so arranged as to readily give either shocks or sparks. He says that “by means of the conductors and jointed tubes, the human body can be in any part affected with either kind of electricity in any convenient manner.”

REFERENCES.--Philosophical Transactions for 1772, 1774, 1778, 1780, 1783, Vol. LXIV. p. 79; Vol. LXVIII. p. 823; Vol. LXX. p. 334; also Hutton’s abridgments, Vol. XIII. pp. 360 (dipping needle), 498; Vol. XIV. pp. 427–446, 688; Vol. XV. p. 388; “General Biog. Dict.,” London, 1833, by John Gorton, Vol. I. (n. p.); Cuthbertson, “Practical Electricity,” London, 1807, pp. 165–168; article “Electricity,” in the “Encycl. Britannica”; “Description of ... Nairne’s ... Machine,” London, 1783 and 1787; Caullet de Veaumorel, “Description de la machine électrique négative et positive de Mr. Nairne,” Paris, 1784; Delaunay’s “Manuel,” etc., Paris, 1809, pp. 7, 12–14.

=A.D. 1782–1783.=--Linguet (Simon, Nicolas, Henri), French advocate (1736–1794), who was an associate of Mallet du Pan in the preparation of the Annales Politiques and who was later on committed to the Bastille in consequence of a visit which he imprudently made to Paris, writes a letter to the French Ministry proposing a novel method of transmitting messages of any length or description by means of some kind of a telegraph, “nearly as rapidly as the imagination can conceive them.” He adds, “I am persuaded that in time it will become the most useful instrument of commerce for all correspondence of that kind; just as electricity will be the most powerful agent of medicine; and as the fire-pump will be the principle of all mechanic processes which require, or are to communicate, great force.”

To Linguet has been attributed the authorship of the anonymous letter which appeared in the Journal de Paris of May 30, 1782, and in Le Mercure de France of June 8, 1782, wherein it is proposed to employ twenty-four pairs of gilt wires, placed underground in separate wooden tubes filled with resin and bearing a knob at each extremity. Between each pair of knobs was to be placed a letter of the alphabet, which would become discernible whenever the electric spark was passed through the wire by means of the Leyden phial.

REFERENCES.--Ternant, Le Télégraphe, Paris, 1881, p. 11; Linguet, “Mém. manuscrit ... signaux par la lumière,” Paris, 1782; all about the “Mercure de France,” in “Bulletin du Bibliophile” No. 7 of July 15, 1902; “Biog. Dict.,” Alex Chalmers, 1815, Vol. XX. p. 290; “Nouv. Biog. Gén.” (Hœfer), Paris, 1860, Vol. XXXI. p. 279; “Biog. Univ.” (Michaud), Vol. XXIV. p. 565.

=A.D. 1782–1791.=--Cassini (Jean Jacques Dominique, Comte de), son of Cassini de Thury, eminent astronomer, makes the very important announcement that, besides the secular variation of the declination, the magnetic needle is subject to an annual periodical fluctuation depending on the position of the sun in reference to the equinoctial and solstitial points.

Cassini’s discovery is contained in a Memoir consisting of two parts, the first part being a letter addressed to L’Abbé Rosier and published by him in the Journal de Physique, while the second part, composed at request of the Académie des Sciences, is that which specially treats of the annual variation in declination.

Besides the last named, we have thus far learned of the secular variation discovered by Gellibrand (Hellibrand) in 1635, as well as of the diurnal and horary variations, first accurately observed by George Graham during the year 1722, and we have likewise been informed of the earliest observations of the dip or inclination, made independently by both Georg Hartmann (A.D. 1543–1544) and by Robert Norman (A.D. 1576), as well as of the determination of the intensity of the inclination by J. C. Borda (at A.D. 1776). For accounts of the secular and annual, as well as of the diurnal and horary variations of the dip, the reader should consult the First Section of Humboldt’s “Cosmos” treating of telluric phenomena and some of the very numerous references therein given.

Speaking of the influence of the sun’s position upon the manifestation of the magnetic force of the earth, Humboldt remarks that the most distinct intimation of this relation was afforded by the discovery of horary variations, although it had been obscurely perceived by Kepler, who surmised that all the axes of the planets were magnetically directed toward one portion of the universe. He says that the sun may be a magnetic body, and that on that account the force which impels the planets may be centred in the sun (Kepler, in “Stella Martis,” pp. 32–34--compare with it his treatise, “Mysterium Cosmogr.,” cap. 20, p. 71). He further observes that the horary variations of the declination, which, although dependent upon true time are apparently governed by the sun as long as it remains above the horizon, diminish in angular value with the magnetic latitude of place. Near the equator, for instance, in the island of Rawak, they scarcely amount to three or four minutes, whilst the variations are from thirteen to fourteen minutes in the middle of Europe. As in the whole northern hemisphere the north point of the needle moves from east to west on an average from 8½ in the morning until 1½ at midday, in the southern hemisphere the same north point moves from west to east (Arago, Annuaire, 1836, p. 284, and 1840, pp. 330–358). Attention has been drawn, with much justice, to the fact that there must be a region of the earth, between the terrestrial and the magnetic equator, where no horary deviations in the declination are to be observed. This fourth curve (in contradistinction to the isodynamic, isoclinic and isogonic lines, or those respectively of equal force, equal inclination and equal declination), which might be called the curve of no motion, or rather the line of no variation of horary declination, has not yet been discovered. No point has hitherto been found at which the needle does not exhibit a horary motion, and, since the erection of magnetic stations, the important and very unexpected fact has been evolved that there are places in the southern magnetic hemisphere at which the horary variations of the dipping needle alternately participate in the phenomena (types) of the hemispheres.

Humboldt also alludes, in the article on “Magnetic Variation,” to his recognition of the “four motions of the needle, constituting, as it were, four periods of magnetic ebbing and flowing, analogous to the barometrical periods,” which will be found recorded in Hansteen’s “Magnetismus der Erde,” 1819, s. 459, and he likewise refers to the long-disregarded nocturnal alterations of variation, for which he calls attention to Faraday “On the Night Episode,” ss. 3012–3024. (See also, Poggendorff’s Annalen der Physik, Bd. XV. s. 330, and Bd. XIX. s. 373.)

The Phil. Trans. for 1738, p. 395, contain the description of a new compass for ascertaining the variation “with greater ease and exactness than any ever yet contrived for that purpose.” This was devised by Capt. Christopher Middleton, whose many interesting observations are to be found in the same volume of the Phil. Trans., p. 310, as well as in the volumes for 1726, p. 73; 1731–1732, 1733–1734, p. 127; 1742, p. 157, and in John Martyn’s abridgment, Vol. VIII. part i. p. 374. Reference should also be made to the volumes for 1754 (p. 875) and 1757 (p. 329), giving the reports of W. Mountaine and J. Dodson upon the magnetic chart and tables of 50,000 observations, likewise to the volume for 1766 containing the report of W. Mountaine on Robert Douglass’ observation, as well as for the record of investigations of the variation made by David Ross on board the ship “Montagu” during the years 1760–1762.

REFERENCES.--Sabine, “On the Annual and Diurnal Variations” in Vol. II of “Observations made ... at Toronto,” pp. xvii-xx, also his Memoir “On the Annual Variation of the Magnetic Needle at Different Periods of the Day,” in Phil. Trans. for 1851, Part II. p. 635, as well as the Introduction to his “Observations ... at Hobart Town,” Vol. I. pp. xxxiv-xxxvi, and his Report to the British Association at Liverpool, 1854, p. 11--Phil. Trans. for 1857, Art. 1, pp. 6, 7--relative to the lunar diurnal magnetic variation. See likewise C. Wolf, “Histoire de l’observatoire depuis sa fondation à 1793”; Houzeau et Lancaster, “Bibl. Gen.,” Vol. II. p. 102; “Mém. de Paris,” Vol. II. p. 74, and Vol. VII. pp. 503, 530; Walker, “Ter. and Cos. Magn.,” Chap. III; Mme. J. Le Breton, “Histoire et Applic.,” etc., Paris, 1884, p. 17; Robison, “Mech. Phil.,” Vol. IV. p. 356; Thos. Young, “Nat. Phil.,” 1845, p. 583.

CASSINI FAMILY

This celebrated family, to which allusion was made under A.D. 1700, deserves here additional notice.

Giovanni Domenico Cassini (1625–1712), the first and greatest of the name, succeeded Buonaventura Cavaliéri in the astronomical chair of the Bologna University in 1650, and remained there until given the directorship of the Paris Royal Observatory upon its completion in 1670. Partly with the assistance of his learned nephew, James Philip Maraldi, Cassini made many important discoveries, among which may be signalled the finding of the first, second, third and fifth satellites of Saturn, as well as the dual character of that planet’s ring, the determination of the rotation of Jupiter, Mars and Venus, and the laws of the moon’s axial rotation. (See Thomson, “Hist. of the Roy. Soc.,” p. 331; “Anc. Mém. de Paris,” I, VIII, X; Thos. Morrell, “Elem. of the Hist. of Phil. and Sc.,” London, 1827, pp. 377–379.)

Jacques (James) Cassini (1677–1756), the only son of the preceding, became director of the Paris Observatory upon the death of his father, made many very important astronomical observations, and wrote several treatises upon electricity, etc. In one of his works, “De la Grandeur et de la Figure de la Terre,” Paris, 1720, he gives an account of the continuation of the measurement of Picard’s arc of the meridian from Paris northward, begun by Domenico Cassini and La Hire in 1680, and recommenced by Domenico and Jacques Cassini in 1700. (See “Mém. de Paris,” Vol. VII. pp. 455, 456, 508, 572; and for years 1705, pp. 8, 80; 1708, pp. 173, 292; 1729, Hist. I., Mem. 321.)

Cesar François Cassini de Thury (1714–1784), son of Jacques, whom he in turn succeeded at the Observatory, was, as above stated, the father of Jean Dominique Cassini (1747–1845). He made numerous researches while in the Director’s Chair, his most remarkable work being the large triangulation of France published in 1744, under the title of “La Méridienne,” etc. (See “Hist. de l’Acad. des Sciences de Paris” pour 1752, p. 10.)

=A.D. 1783.=--Robespierre (François-Maximilien-Joseph-Isidore de), who afterward became leader of the famous French Jacobin Club, and was at the time practising law in his native town of Arras, distinguishes himself by successfully defending the cause of the Sieur de Vissery de Boisvalé, a landed proprietor of that place, who had erected a lightning conductor on his house, “much to the scandal of the discreet citizens” of the locality--“Deistical philosophy; away with it!” (Eighth “Britannica,” Vol. XIX. p. 233).

Mr. de Boisvalé’s case was an appeal from a judgment delivered by the sheriff of Saint-Omer, ordering the destruction of the lightning conductor, and its printed report bears the following epigraph:

“L’usage appuyé sur les temps Et les préjugés indociles. Ne se retire qu’à pas lents Devant les vérités utiles.”

Jean Paul Marat, docteur en médecine et médecin des Gardes de corps de M. le Comte d’Artois, who, like Robespierre, was a member of the French National Convention as well as a declared enemy of the Girondins, and who was killed by Charlotte Corday, July 13, 1793, made many electrical experiments. These greatly interested Benjamin Franklin, who used to visit him (Ninth “Encycl. Brit.,” Vol. XV. p. 526). He was the author of many electrical works during the years 1779–1784, notably “Découvertes sur le feu, l’électricité et la lumière,” “Recherches Physiques,” and a memoir on medical electricity (“Œuvres de Marat,” Paris, 1788; A. Bougeart, “Marat, l’ami du peuple,” 1864; F. Chevremont, “Jean Paul Marat,” 1881).

REFERENCES.--Ronalds’ “Catalogue,” p. 434; _La Lumière Electrique_ for Sept. 5, 1891; the Electrician, London, Sept. 11, 1891.

=A.D. 1783.=--Wilkinson (C. H.), Scotch physician, publishes at Edinburgh his “Tentamen Philosophico-medicum de Electricitate,” which is followed, during 1798 and 1799, by other works upon electricity, wherein he cites a number of marvellous cures of intermittent fevers similar to those made by Cavallo, also of amaurosis (goutte sereine) and of quinsy (squinancie) like those performed by Lovet, Becket and Mauduyt.

During the year 1804 appeared the first edition, in two volumes, of his “Elements of Galvanism in Theory and Practice,” containing a very comprehensive review of the discovery from the time of Galvani’s early experiments. In this last-named work, however, he shows that incipient amaurosis and the completely formed gutta serena have not yielded to his own treatment by galvanic influence as had been the case with Dr. C. J. C. Grapengieser, who published many accounts of surprising cures (Grapengieser, “Versuche den Galvanismus ...” Berlin, 1801 and 1802, or Brewer and Delaroche, “Essai ...” Paris, 1802). The whole of Chap. XXXVI is devoted to the application of galvanism to medicine, whereto allusion had already been made in the first chapter of the same work.

Wilkinson refers also to the electricity of the torpedo, and to the observations made thereon by Hippocrates, Plato, Theophrastus, Pliny and Ælian, also by Belon, Rondelet, Salviana and Gesner, as well as by Musschenbroek, Redi, Réaumur, Walsh, Hunter, Spallanzani, ’Sgravesande, Steno, Borelli, Galvani and others. Much space is likewise given to the observations recorded on animal electricity, notably by Fontana, De La Méthérie, Berlinghieri, Vassali-Eandi, Humboldt, Pfaff, Lehot, Hallé, Aldini, and to the experiments of Valli as they were repeated before the French Academy of Sciences and before the Royal Society of Medicine of Paris, in presence of M. Mauduyt. When treating of the powers of galvanism as a chemical agent, reference is made to the decomposition of water, thus first effected in 1795 by Creve, the discoverer of metallic irritation, and to the operations of Nicholson and Carlisle, Dr. Henry, Cruikshanks, Haldane, Henry Moyes, Richter, Gibbes, etc.

REFERENCES.--J. J. Hemmer, “Commentat Palatinæ,” VI, Phys., p. 47; Bertholon, “Elec. du Corps Humain,” 1786, Vol. I. pp. 314, 330, 483, and Vol. II. p. 299; “Bibl. Britan.,” 1808, Vol. XXXVIII. p. 270 (Phil. Mag., No. 105); Annales de Chimie, Vol. LXXVIII. p. 247; Phil. Mag., Vol. XXIX. p. 243, and Vol. XLIX. p. 299; F. Buzzi, “Osservazione ... amaurosi ... elettricita,” Milano, 1783 (“Opus. Scelti,” Vol. VI. p. 359); Nicholson’s Journal, Vol. VIII. pp. 1, 70, 206; also Vol. X. pp. 30–32, for letter relative to certain erroneous observations of Mr. Wilkinson respecting galvanism, by Mr. Ra. Thicknesse, who also wrote in Vol. IX. pp. 120–122, explaining the production of the electric fluid by the galvanic pile.

=A.D. 1783.=--Saussure (Horace-Benedict de), Professor of Physics at the University of Geneva and founder of the Society for the Advancement of the Arts in the same city, is the inventor of an electrometer designed to ascertain the electrical state of the atmosphere, which will be found described in Vol. VIII. p. 619 of the 1855 “Encycl. Britannica.”

He observed that electricity is strongest in the open-air, that it is weak in streets, under trees, etc., and that during the summer and winter, by night as well as by day, when the atmosphere is free from clouds, the electricity of the air is always positive. In contradistinction, Mr. T. Ronayne found in Ireland that the electricity of the atmosphere is positive in winter when the air is clear, but that it diminishes in frosty or foggy weather and that he could detect no electricity in the air during summer except on the approach of fogs, when the electricity proved to be positive. During the year 1785, M. de Saussure observed at Geneva that, during the winter, the intensity of atmospherical electricity attained its first maximum at 9 a.m., diminishing from that hour until it reached its minimum at 6 p.m., after which it began to increase until attaining its second maximum at 8 p.m., diminishing gradually thereafter till it recorded its second minimum at 6 a.m. During the summer he found the electricity increasing from sunrise till between 3 and 4 p.m., when it would reach its maximum; after that it appeared to diminish till the dew fell, when it again became stronger, but was scarcely sensible during the night.

Sir David Brewster informs us in his able article on “Electricity” in the “Britannica” that De Saussure made a number of elaborate experiments on the electricity of evaporation and combustion. He observed at first that the electricity was sometimes positive and sometimes negative when water was evaporated from a heated crucible, but in his subsequent trials he found it to be always positive in an iron and in a copper crucible. In a silver, also in a porcelain crucible, the electricity was negative and the evaporation of both alcohol and of ether in a silver crucible also gave negative electricity. M. de Saussure made many fruitless attempts to obtain electricity from combustion, and he likewise failed in his efforts to procure it from evaporation without ebullition.

To De Saussure is often erroneously attributed the authorship of Lullin’s “Dissertatio physica de electricitate,” alluded to at A.D. 1766.

REFERENCES.--De Saussure’s “Dissertatio de Igne,” “Exposition abrégée,” etc. (translated by Giuseppe Toaldo, in both his “Della maniera,” etc., and “Dei conduttori,” etc., Venezia, 1772 and 1778), “Voyage dans les Alpes,” all published at Geneva, 1759, 1771, 1779, also the important 1786 Neuchatel edition of the last-named work, more particularly at pp. 194, 197, 203, 205, 206, 211, 212, 216, 218, 219, 228, 252, 254 of Vol. II, and at pp. 197, 257 of Vol. IV; likewise his Memoirs relative to the electricity of the atmosphere, of vegetables, of microscopic animals, etc., etc., alluded to in Journal de Physique for 1773, 1784, 1788; in Journal de Paris for 1784, 1785; in Vol. I of Lazaro Spallanzani’s “Opuscoli di fisica,” etc., for 1776; in Vol. III of the “Opuscoli Scelti di Milano,” and in the Philosophical Transactions. See also Jean Senebier, “Mémoire historique,” etc., Genève, 1801; Louis Cotte in his “Traité,” etc., “Mémoires,” etc., “Observation,” etc., Paris, 1762, 1769, 1772; in the “Mémoires de Paris,” Année 1769, “Hist.,” p. 19; Année 1772, “Hist.,” p. 16, and in the Journal de Physique for 1783, Vol. XXIII; the experiments of MM. Becquerel and Brachet in Becquerel’s “Traité d’El. et de Magn.,” Paris, 1836, Vol. IV. p. 110; Theodor Ægidius von Heller, “Beobach d. Atmosphär. Elektricität.” (F. A. C. Gren, “Neues Journal der Physik” for 1797, Vol. IV); Faujas de St. Fond, “Description,” etc., Vol. II. p. 271, as per George Adams’ “Essay on Electricity,” London, 1799, p. 419; Noad, “Manual,” etc., London, 1859, p. 16; Poggendorff, Vol. II. p. 755; Rozier, XXXI. pp. 317, 374; XXXIV. p. 161; articles “Meteorology and Electricity” in the “Encyclopædia Britannica”; Thomas Young, “Course of Lectures,” etc., London, 1807, Vol. II. pp. 447, 466–471.

=A.D. 1784.=--Swinden (Jan Hendrik Van) (1746–1823), who had been made Professor in the University of Franequer at the early age of twenty (1767), and was at this time occupying the Chair of Natural Philosophy and Mathematics at Amsterdam, publishes in three volumes, at La Haye, his “Recueil de Mémoires sur l’Analogie de l’Electricité et du Magnétisme,” etc. (“De Analogia ...” in Vol. II of the “Neue Abhandl. der Baierischen Akad. Phil.”). The latter contains all the essays sent to the Electoral Academy of Bavaria on the subject--“Is There a Real and Physical Analogy Between Electric and Magnetic Forces; and, if Such Analogy Exist, in What Manner Do These Forces Act Upon the Animal Body?”

Van Swinden’s essay, which gained him one of the prizes, shows that, in his opinion, the similarity between electricity and magnetism amounts merely to an apparent resemblance, and does not constitute a real physical analogy. He infers from this that these two powers are essentially different and distinct from one another, but the contrary opinion was maintained by Profs. Steiglehuer and Hubner, who contended that so close an analogy as that exhibited by these two classes of phenomena indicated the effects of a single agent, varied only in consequence of a diversity of circumstances.

The eminent professor, Gerard Moll, of Utrecht, has communicated to the Edinburgh Journal of Science (1826, Vol. I. part ii. pp. 197–208) a biographical notice of Van Swinden, wherein he gives a list of the latter’s principal works and there speaks of one of his best-known productions in following manner: “The Positiones Physicæ (Opusc. Scelti, X. 7), as far as they are published (Harderovici, 1786, Vol. I and Vol. II. part i.), are allowed to rank among the best elements of natural philosophy, and have been found by actual experience to belong to the best sources from which the young student could draw his information on those parts of natural philosophy, and its general principles, as are contained in the first volume and part of the second, which is all that was published. The work itself is on a most extensive plan; and the multifarious avocations which crowded on Van Swinden in Amsterdam delayed the publications, and made him afterward abandon all thoughts of completing a work which would have done the greatest honour to its author, and which even now, unfinished as it is, is celebrated as an excellent specimen of sound reasoning and profound learning.”

Van Swinden was the first President of the Royal Institute of the Netherlands. He entered with ardour into all the new discoveries of his day and kept up an extensive correspondence with many of the leading scientific characters of the time, notably with the Swiss philosopher, Charles Bonnet (whose “Contemplations de la Nature” he annotated extensively); with Dr. Matthew Maty (who became secretary of the Royal Society upon the resignation of Dr. Birch in 1765, and who was appointed, by the king, principal librarian of the British Museum upon the death of Dr. Gowin Knight, 1772); with the eminent French physician, Michel-Augustin Thouret, Dean of the Paris “Faculté de Médecine”; as well as with Delambre, Euler, De Saussure, and many others who have been named elsewhere in this “Bibliographical History.”

The following is further extracted from Prof. Moll’s interesting paper: “Mr. Biot, in his treatise on Natural Philosophy (Tome III. p. 143) asserts that we are indebted to Cassini IV. (see Jean Dominique, Comte de Cassini, at A.D. 1782–1791) for much of what we know even about the diurnal variation of the needle. This, I think, is not fair. We do not mean to undervalue Mr. Cassini’s observations, but it is unquestionable that long before the publication of that philosopher’s work, Mr. Van Swinden had observed and published (‘Recherches sur les aiguilles aimantées et leurs variations’--Mémoires présentés à l’Académie des Sciences de Paris, Tome VIII--prize essay 1777) that which Mr. Biot less accurately is pleased to ascribe to his countryman. In this respect, however, Mr. Van Swinden was treated with more justice by other eminent philosophers, such as Haüy, Halley and Burkhardt.” (Consult also the “Acta Acad. Petrop.” for 1780, Part I. Hist. p. 10.)

In the afore-named very meritorious work, “Recueil de Mémoires,” etc., crowned by the Bavarian Academy, Van Swinden has treated fully of the then current theories relative to electrical and magnetical phenomena, reviewing the entire field of their application. In so doing he has necessarily made numerous references to discoverers and experimenters of all countries, the names of many of which appear in the present compilation, and while it is, of course, useless here to quote these anew, it has been thought best, for a record, to specify such as are infrequently met with, and which appear in many of his most important articles, even at the risk of being accused of diffuseness or prolixity. They are as follows:

REFERENCES.--John T. Needham (Vol. IV, Mem. Brussels Acad. for 1783); Phil. Trans., 1746, p. 247; J. G. Lehmann (“Abhandlung von Phosph.”; “Von Magnet Theilen im Sande,” “Novi Com. Acad. Petrop.,” Vol. XII. p. 368, etc.); M. De La Cépède, “Essai sur l’El. nat et artif.”; C. E. Gellert (“Com. Acad. Petrop.,” Vol. XIII. p. 382, Exp. 15, 16); J. F. Henckel, “Pyritologia,” etc.; J. E. Von Herbert, “Theor. Phæn. Elect.,” cap. 4, prop. 8; C. F. M. Déchales, “Mundus Mathematicus,” lib. 1, _Quartus Exper. Ordo._, exp. 16, Tome II. p. 488, ed. 2, etc.; M. Marcel’s Dissertation on powdered magnets, which appears in the Dutch “Uitgezogte Verhandelingen,” Vol. I. p. 261, etc.; Jean M. Cadet (“Nova Acta. Physico. Med. Acad. Natur. Curios.,” Tome III); Abbé Giraud-Soulavie (“Comment. ... Œuvres de Mr. Hamilton,” note 4, p. 303); J. B. Le Roy (“Mém. de l’Acad. de Paris,” for 1753, p. 447; for 1772, p. 499; Jour. de Phys., Vol. II); Rudolph Richard (“Magazin d. Hamb.,” IV. p. 681); Gilles A. Bazin, “Descrip. des Cour, Mag.,” Plates 14, 16–18; J. F. Gross, “Elektrische Pausen,” Leipzig, 1776; Jour. de Phys., Vol. X. p. 235; Niccolo Bammacaro, “Tentamen de vi Electrica,” etc., s. 6; Samuel Colepress (Phil. Trans., 1667, No. 27, Vol. I. p. 502); E. F. Du Tour, “Discours sur l’aimant,” s. 27; “Recueil des Prix de l’Acad. de Paris,” Tome V. mém. ii. p. 49; “Mém. Math, et Phys.”; Mr. Calendrin, at Van Swinden’s, Vol. I. pp. 233, etc.; M. Blondeau (“Mém. de l’Acad. de Marine,” Brest., Tome I. s. 46, pp. 401–431, 438); J. A. Braun, “Observations,” etc.; “Novi. Comment. Acad. Petrop.,” Vol. VII. pp. 388, 407; M. Antheaulme (“Mém. sur les aimants artif.” (prize essay), 1760; “Mém. de l’Acad. Roy.,” 1761, p. 211; Van Swinden, 1784, Vol. II. pp. 95, 170); J. N. Reichenberger, “Directorium magneticum magneticis,” etc., and “Hydrotica,” as at Van Swinden, 1784, Vol. II. pp. 272–273; Geo. C. Schmidt, “Beschr., einer Elektrisir Masch.,” etc., 1778; M. De la Folie (Jour, de Phys., 1774, Vol. III. p. 9); Cölestin Steiglehner, “Obs. phaenom. elect.,” “Ueber die Annal der Elek. und des Magn.”; Lorenz Hubner, “Abh. u. d. Annal. u. mag. Kraft”; Jos. Thad. Klinkosch, “Schreiben,” etc., “Beschreib. d. Volta ... Elektrophors.” Reference should also be made to Noad, “Manual,” etc., p. 641; Encycl. Brit., 1857, Vol. XIV. p. 6; “Messager des Sciences et des Arts,” Gand, 1823, pp. 185–201, detailing all of Van Swinden’s works; Antoine Thillaye’s treatise presented to the Ecole de Médecine le 15 Floréal, An. XI; Butet (“Bull, des Sc. de la Soc. Philom.,” No. 43, Vendémiaire, An. IX).

=A.D. 1784.=--Cotugno (Domenico), Professor of Anatomy at Naples, thus addresses Le Chevalier G. Vivenzio under date October 2, 1784: “The observation which I mentioned some days ago, when we were discoursing together of the electrical animals, upon which I said I believed the mouse to be one of that number, is the following: Toward the latter end of March, I was sitting with a table before me and observing something to move about my foot, which drew my attention. Looking toward the floor I saw a small domestic mouse, which, as its coat indicated, must have been very young. As the little animal could not move very quick, I easily laid hold of it by the skin of the back and turned it upside down; then with a small knife that laid by me, I intended to dissect it. When I first made the incision into the epigastric region, the mouse was situated between the thumb and finger of my left hand, and its tail was got between the last two fingers. I had hardly cut through part of the skin of that region, when the mouse vibrated its tail between the fingers, and was so violently agitated against the third finger that, to my great astonishment, I felt a shock through my left arm as far as the neck, attended with an internal tremor, a painful sensation in the muscles of the arm, and such giddiness of the head, that, being affrighted, I dropped the mouse. The stupor of the arm lasted upward of a quarter of an hour, nor could I afterwards think of the incident without emotion. I had no idea that such an animal was electrical; but in this I had the positive proof of experience.” (See G. Vivenzio, “Teoria e pratica della elettricità med.” ... Napoli, 1784.)

Cotugno’s observations attracted much attention throughout Italy and gave rise to many experiments, notably by Vassalli, who, however, merely concluded from them that the animal’s body could retain accumulated electricity in some unaccountable manner.

REFERENCES.--Essai sur l’histoire, etc., J. B. Biot, p. 9; Journal de Physique, XLI. p. 57; Mémoires Récréatifs, etc., par Robertson, Paris, 1840, Vol. I. p. 233; Cavallo, Electricity, London, 1795, Vol. III. p. 6; Izarn, Manuel, Paris, 1804, p. 4; Journal Encyclopédique de Bologne, 1786, No. 8; Poggendorff, Vol. I. p. 417; Sue, aîné “Hist. du Galv.,” Vol. I. pp. 1–2.

=A.D. 1785.=--Coulomb (Charles Augustin de), the founder of electro-statics and of the school of experimental physics in France, invents the torsion balance, with which he discovers the true law of electric and magnetic attractions and repulsions. Some have asserted that Lord Stanhope had previously established the law with regard to electricity, but it has not been seriously questioned that its extension to magnetism belongs exclusively to Coulomb. Johann Lamont (“Handbuch ...” p. 427) gives the credit of the latter discovery to Giovannantonio Della Bella, of Padua, who is mentioned by Poggendorff (“Biog.-Liter. Handwörterbuch,” Vol. I. p. 139) as the author of several works on electricity and magnetism, but the claim does not appear to be established upon any satisfactory foundation.

With his torsion balance, or rather electrometer, Coulomb measured the force by the amount of twist it gave to a long silken thread carrying a horizontal needle, constructed, preferably, of a filament of gum-lac or of straw covered with sealing-wax. From his experiments he concluded: That the attractive force of two small globes, one electrified positively and the other negatively, is in the inverse ratio of the squares of the distances of their centres, and that the repulsive force of two small globes, charged either with positive or negative electricity, is inversely as the squares of the distances of the centres of the globes (“Mém. de l’Acad. Roy. des Sciences,” 1784, 1785).

In one of his three memoirs to the French Academy during 1785, he states that a balance used by him was so delicate that each degree of the circle of torsion expressed a force of only one hundred-thousandth of an English grain, that another, suspended by a single fibre of silk four inches long, made a complete revolution with a force of one seventy-thousandth of a grain, and turned to the extent of a right angle when a stick of sealing-wax, which had been rubbed, was presented to it at the distance of a yard. It is said that a similar electrometer has been constructed in which the movement of one degree recorded a force not exceeding twenty-one million six-hundred-thousandths of a grain.

The many valuable experiments made by Coulomb on the dissipation of electricity and upon the distribution of electricity upon the surfaces of bodies are fully recorded in the able article of Sir David Brewster in the “Encyclopædia Britannica” (F. C. Achard, “Mém. de Berlin,” 1780, p. 47); M. Vernier, “De la dist. ... conducteurs,” Paris, 1824; J. L. F. Bertrand, “Programme d’une thèse ...” Paris, 1839; D. Bourdonnay, “Sur la dist. ... conducteurs,” Paris, 1840; Ed. A. Roche in “Montp. Acad. Sect. Sciences,” Vol. II. p. 115).

He discovered that shellac is the most perfect of all insulators, also that a thread of gum-lac insulates ten times better than a dry silken thread of the same length and diameter: and he established the law that the densities of electricity insulated by different lengths of fine cylindrical fibres, such as those of gum-lac, hair, silk, etc., vary as the square root of the lengths of the fibre.

Besides the communications above alluded to, Coulomb sent to the French Academy, during the years 1786, 1787, 1788 and 1789, many papers upon Electricity and Magnetism, and, up to within two years of his death (1806), he made many notable experiments, especially in magnetism, of which full accounts are given in several of the Mémoires noted at foot. The theory of the two magnetic fluids appeared in his 1789 paper. It is also in this same paper that Coulomb describes his improved method of making artificial magnets by employing compound magnets as first made use of by Gowin Knight and as explained at A.D. 1746. Still further improvements in these were brought about more particularly by the young Flemish scientist, Etienne Jean Van Geuns (1767–1795), by Jean Baptiste Biot (see A.D. 1803), and by the Rev. Dr. Scoresby during the year 1836.

Coulomb found that a steel wire is, by twisting, rendered capable of being nine times more strongly magnetized; that the magnetic power dwells on the surface of iron bodies and is independent of their mass; that the directive force of a magnetized bar reached its maximum when tempered to a bright cherry-red heat at 900 degrees, and that every substance is susceptible of magnetism to a degree of actual measurement. This last important research was communicated by him to the French Institute during the year 1802. His experiments proved that a grain of iron could communicate sensible magnetism to twenty pounds’ weight of another substance, and that when even beeswax had incorporated with it a portion of iron filings equal only to the one hundred-and-thirty-thousandth part of its weight it was yet sensibly affected by the magnet.

According to Dr. Thomas Young, Coulomb’s improvements in the theory of electricity may be considered as having immediately prepared the way for the elegant inventions of Volta and for the still more marvellous discoveries of Davy. Dr. Young gives reports of some of Coulomb’s experiments at p. 439, Vol. II of his “Course of Lectures” London, 1807 (“Journal of the Royal Institution” Vol. I. p. 134; “Décade Philosophique,” No. 21).

REFERENCES.--“Mém. de l’Acad. Royale des Sciences,” Paris, 1784, p. 266; 1785, pp. 560, 569, 578, 612; 1786, p. 67; 1787, p. 421; 1788, p. 617; 1789, p. 455; “Mém. de l’Institut,” Vol. III. p. 176; Vol. IV. p. 565, and Vol. VI. for 1806; “Mém. de Math. et de Phys.” Vols. VIII and IX; “Mémoires de Coulomb,” Vol. I of the “Collection de Mémoires relatifs à la Physique,” Paris, 1884; “Cat. of Sc. Papers Roy. Soc.,” Vol. III. p. 73; “Abstracts of Papers of Roy. Soc.,” Vol. II. p. 402; “Bull. de la Soc. Philom.,” Nos. 3, 31, 61, 63, and for 1795, 1802; Journal de Physique, Vols. XLV (II), pp. 235, 448; LIV. pp. 240, 267, 454; LV. p. 450 (for Carradori’s report); Ch. N. A. De Haldat du Lys (“Mém. de Nancy” for 1841); Phil. Magazine, Vols. XI. p. 183; XII. p. 278; XIII. p. 401; XV. p. 186; Rozier, XXVII. p. 116; XLIII. p. 247; Gilbert, XI. pp. 254, 367; XII. p. 194; Dr. Young, “Course of Lectures,” London, 1807, Vol. I. pp. 682, 685, 686; “Royal Society Cat. of Sc. Papers,” Vol. II. p. 73; Eighth “Britannica,” Vol. XIV. pp. 37–38; Humboldt, “Cosmos,” 1859, Vol. V. p. 61; Schaffner, “Manual,” 1859, p. 56; Biot’s article in the “Biographie Universelle” and Biot’s “Traité de Physique,” Paris, 1816, Vols. II, III; Dr. Thomas Thomson, “Outline of the Sciences,” etc., London, 1830, pp. 350, 351, 379–422; Harris, “Rudim. Magn.,” Parts I, II. p. 56. See also description of the electrometer of Colardeau and the electro-micrometer of Delaunay, in the latter’s “Manuel,” etc., Paris, 1809, pp. 66, 76–80, and Plate V. fig. 61, as well as Libes’ “Dict. de Phys.,” Vol. I. p. 406.

=A.D. 1785.=--The Canon Gottoin de Coma, friend of Alessandro Volta, observes that an iron wire about thirty feet in length will give a sound under certain conditions of the atmosphere when stretched in the open air. The circumstances that accompany, as well as those that favour the production of the phenomenon, says Prescott, demonstrate that it must be attributed to the transmission of atmospheric electricity. This transmission does not occur in a continuous manner, like that of a current, but is observable by a series of discharges.

REFERENCES.--Knight’s Mechanical Dictionary, 1876, Vol. III. p. 2515; Prescott’s “The Speaking Telephone,” etc., 1879, p. 122; Encyl. Britannica, 1860, Vol. XXI. p. 631.

=A.D. 1785.=--Marum (Martin Van), a Dutch electrician who had in 1776 taken the degree of M.D. at the Academy of Gröningen, constructs for the Teylerian Society at Haarlem, with the assistance of John Cuthbertson, an electrical machine said to be the most powerful theretofore made. According to Cavallo (Nat. Phil., 1825, Vol. II. p. 194) it consisted of two circular plates of French glass, each sixty-five inches in diameter, parallel with each other on a common axis, and about seven and a half inches apart. Each plate was excited by four rubbers, the prime conductor being divided into two branches which entered between the plates and, by means of points, collected the electric fluid from their inner surfaces only.

In Van Marum’s machine, the positive and negative electricity could only be obtained in succession, but Dr. Hare, of the University of Pennsylvania, remedied this by causing the plates to revolve horizontally. It is said the machine was so powerful that bodies at a distance of forty feet were sensibly affected; a single spark from it melted a leaf of gold and fired various kinds of combustibles; a thread became attracted at the distance of thirty-eight feet, and a pointed wire was tipped with a star of light at a distance of twenty-eight feet from the conductor.

Descriptions of his machines are given by Dr. Van Marum in letters to the Chevalier Marsiglio Landriani and to Dr. Ingen-housz, both printed in Haarlem during 1789 and 1791. The first quarto volume of Nicholson’s Journal also contains a reference thereto and gives (p. 83) the extract from a letter read June 24, 1773 (Phil. Trans., Vol. LXIII. pp. 333–339), addressed to Dr. Franklin, F.R.S., by John Merwin Nooth, M.D., who describes improvements by which machines are rendered effective in all kinds of weather. Nooth was the inventor of the silk flap, of which mention was made in the description of Cavallo’s machine (under A.D. 1775).

Van Marum also constructed a powerful battery, the metallic coatings of which were equal to 225 square feet, enabling him to give polarity to steel bars nine inches long, nearly half an inch wide and one-twelfth of an inch thick, as well as to sever a piece of boxwood four inches diameter and four inches long, and to melt three hundred inches of iron wire one hundred-and-fiftieth of an inch in diameter, or ten inches of one-fortieth of an inch in diameter. It is said that, during these experiments, the report was so loud as to stun the ears, and the flash so bright as to dazzle the sight.

Dr. Van Marum likewise made experiments upon the electricity developed during the melting and cooling of resinous bodies, which are detailed in the article “Electricity” 8th Edit. “Encyclopædia Britannica,” Vol. VIII. p. 565, and also upon the effects of electricity on animals and vegetables, which are given at pp. 49–51 of the article “Electricity” in the “Library of Useful Knowledge,” as well as in the 1855 Edit. “Encyclopædia Britannica,” Vol. VIII. pp. 602, 603.

In 1785 again Van Marum discovered that electric sparks, on passing through oxygen gas, gave rise to a peculiar sulphurous or electrical odour, which Cavallo called “electrified air,” and the presence of which Dr. John Davy, brother of Sir Humphry Davy, found the means of detecting.

During the month of October 1801 Volta wrote a letter to Van Marum asking him to make, in concert with Prof. C. H. Pfaff, of Kiel, several experiments on the electricity of the pile with the very powerful apparatus of the Teylerian Society. The extended researches of these two scientists are embodied in the Phil. Mag., Vol. XII. p. 161, as well as in the “Lettre à Volta” etc., published at Haarlem during 1802, and are likewise treated of in a very complete manner throughout Chaps. XVI and XXXII of Wilkinson’s well-known work on galvanism. Their united observations confirm the doctrine of Volta as to the identity of the current of the fluid put in motion by the voltaic pile and that to which an impulsion is given by an electrical machine. Thus is answered the question asked during May 1801 by the Haarlem Society of Sciences, viz. “Can the voltaic pile be explained in a satisfactory manner by the known laws and properties of electricity; or is it necessary to conclude the existence of a particular fluid, distinct from the one which is denominated electrical?” They also demonstrated that the current put in motion by the voltaic pile has an enormous celerity “which surpasses all that the imagination can conceive.” With a pile of one hundred and ten pairs of very large copper and zinc plates, they made experiments on the fusion of iron wires and ascertained the causes of the more considerable effects of large piles in the fusion and oxidation of metals, proving, among other facts, as Biot and Cuvier had already done, that a part of the oxygen is absorbed whether the operation be carried on in the open air or in vacuo (Biot and Cuvier, Soc. Philomathique, An. IX. p. 40; Annales de Chimie, Vol. XXXIX. p. 247).

Another of Van Marum’s experiments is related in a letter to M. Berthollet, wherein he says: “... I have succeeded in the decomposition of water, by means of the current of the electrical machine, provided with a plate of thirty-one inches diameter, constructed by me on a new plan (see the Journal de Physique for June, 1795).... I took a thermometrical tube, of the kind employed in making the most sensitive thermometers of Crawford and Hunter, for which purpose I had procured several of these tubes some time before in London. Its diameter interiorly was not more than the one-hundredth part of an inch; and I introduced into it an iron wire of the diameter of about the three-hundredth part of an inch, to the depth of about twelve inches. I now closed the end of my thermometrical tube with sealing wax in such a way that the extremity of the iron wire should scarcely project, and I placed the tube itself, by means of a cork, within a larger tube containing water. The rest of the apparatus was arranged in the customary manner. By directing the powerful current of the above-mentioned machine to this apparatus, the copper ball belonging to which, placed on the thermometrical tube, was at the distance of about three or four lines from the conductor, I succeeded in decomposing the water with a promptitude nearly equal to that which results from a voltaic pile of a hundred pairs of metallic plates.” This method of decomposing water is a very tedious one, and is in fact the result of an interrupted explosion, while the process of Dr. Wollaston (alluded to at A.D. 1801) is tranquil and progressive.

REFERENCES.--“Biogr. Univ.,” Vol. XLII. p. 600; J. G. Heinze, “Neue elekt. versuche ...” Oldenberg, 1777; Tries’ claim to Van Marum’s machine in Rozier, XL. p. 116; Prieur’s extract in Annales de Chimie, Vol. XXV. p. 312; “Verhand. Genootsch. Rott.,” VI for 1781 and VIII for 1787; Journal de Physique, XXXI, 1787; XXXIII, 1788 (Marum en Troostwyk); XXXIV, 1789; XXXVIII, 1791; XL, 1792; “Journal du Galvanisme,” XI, Cahier, p. 187; “Journal des Savants” for August 1905; “Revue Scientifique,” Paris, April 8, 1905, pp. 428–429; _Nicholson’s Journal_ for March 1799, Vol. II. p. 527; Harris, “Electricity,” pp. 62, 90, 171; Cuthbertson, “Practical Electricity,” London, 1807, pp. 166, 172, 197, 225; Cavallo, “Electricity,” 4th ed., Vol. II. p. 273; “Lib. of Useful Knowledge,” “Electricity,” p. 45; Wilkinson, “Elements of Galvanism,” etc., London, 1804, Vol. II. pp. 106–128, 384; “Teyler’s Tweede Genootschap”; Gilbert, Annalen, I. pp. 239, 256; X. p. 121; Rozier, XXVII. pp. 148–155; XXXI. p. 343; XXXIV. p. 274; XXXVIII. pp. 109, 447; XL. p. 270; “Opus. Scelti,” IX. p. 41; XIV. p. 210.

=A.D. 1785.=--Sigaud de la Fond, Professor at the Collège d’Harcourt in Paris, publishes in the latter city his “Précis historique et expérimental des phénomènes electriques,” wherein he states having, as far back as 1756, made use of a circular plate machine provided with cushions and similar in shape to that which many claim to have originated with Ingen-housz and with Ramsden. (See A.D. 1779 and A.D. 1768.)

Sigaud de la Fond is also the author of “Description d’un Cabinet de Physique” (1784), “Cours de Physique,” etc. (1786), “Examen.,” etc. (1803) and of several treatises on medical electricity.

REFERENCES.--“Journal de Physique,” Vol. II. 1773; Figuier, “Exposition et Histoire,” Paris, 1857, pp. 50, 74–76, 178; Poggendorff, Vol. II. p. 927.

=A.D. 1785.=--In the “Nachricht von einer neuen Elektrisirmaschine des Herrn Walkiers von Saint Amand,” the last named gives a description of the electrical machine presented by him in 1784 to the Belgian Academy of Sciences.

It is also described and outlined in Delaunay’s “Manuel” named below, but, although very powerful in its effects, cannot be made readily available in consequence of its huge dimensions. M. Caullet de Veaumorel suggested the feasibility of changing the cylinders from a horizontal to a vertical position.

REFERENCES.--“Lichtenberg’s Mag.,” Vol. III. 1 st. p. 118; Delaunay, “Manuel,” etc., 1809, pp. 14–16.

=A.D. 1785.=--Adams (George), mathematical instrument maker to his Majesty, writes an enlarged edition of his “Essay on Electricity,” etc., which first appeared the year previous and wherein, as its full title indicates, he endeavours to explain the theory and practice of that science and the mode of applying it to medical purposes. He illustrates many experiments and gives an Essay on Magnetism, in the treatment of which latter he acknowledges the valuable aid of Dr. J. Lorimer.

The fifth and last edition of the “Essay,” which was issued by William Jones in 1799, four years after Adams’ death, contains a communication on the subject of Medical Electricity by John Birch, the author of “Della Forza dell’ Elettricita,” etc., Napoli, 1778.

At p. 86 of the 1799 “Essay,” etc., Adams relates that, while M. Loammi Baldwin (“Memoirs of Amer. Acad.,” Vol. I. p. 257) held the cord of his kite during the approach of a thunderstorm, he “observed himself to be surrounded by a rare medium of fire, which, as the cloud rose nearer the zenith, and the kite rose higher, continued to extend itself with some gentle faint flashes.” At pp. 137, 186 and 222, he alludes to “A. Brook’s Miscellaneous Experiments and Remarks on Electricity,” etc., as well as to the Rev. John Lyon’s “Experiments and Observations of Electricity,” and refers to the “Journal of Natural Philosophy” (Vol. II. p. 438) for Nicholson’s experiments on the plus and minus of electricity.

=A.D. 1785.=--La Méthérie (Jean Claude de), French physicist naturalist, becomes sole editor of the “Journal de Physique, de chimie et d’histoire naturelle,” and publishes in Paris his “Essai Analytique,” etc., wherein amongst other observations he asserts that the electric spark results from the combination of oxygen with hydrogen.

He considers that all bodies exist in an electrical or magnetical condition, that we are only a temporary aggregation of molecules of matter governed in different ways by nature’s laws, and that excitability is produced by galvanic action resulting from the superposition of nervous and muscular fibres.

He is also the author of very interesting treatises on animal electricity communicated to the Journal de Physique (Vol. XLII. pp. 252, 255, 292), and of which an account is given in Sue’s “Histoire du Galvanisme,” Paris, 1802, Vol. I. pp. 64–68. The last-named work also gives, at p. 80, an account of the letter on “Galvanism” sent to M. De La Méthérie by M. Leopold Vacca-Berlinghieri (Journal de Physique, Vol. XLI. p. 314).

REFERENCES.--“Biographie Générale,” Vol. XXIX. p. 209; Rozier, XLI. p. 437; Delaunay, “Manuel,” etc., 1809, p. 15, also Delaunay’s letter in Phil. Mag., Vol. XXVII. p. 260; C. H. Wilkinson, “Elements of Galvanism,” London, 1804, Vol. I. p. 62; Vol. II. p. 9; “Opus. Scelti,” XXI. p. 373; _Journal de Physique et Chimie_ (of which La Méthérie remained editor up to the time of his death, during 1817), Vols. LIII, LIV, Pluviose, An. XI. p. 161; also p. 157 for letter sent him by Giuseppe Izarn; Ann. di Chim. di Brugnatelli, Vol. XIX. p. 156; Aubert, “Elektrometische Flasche,” Paris, 1789.

=A.D. 1785.=--According to Prof. Tyndall, George Cadogan Morgan sought to produce the electric spark in the interior of solid bodies. He inserted two wires into wood and caused the spark to pass between them; the wood was illuminated with blood-red light or with yellow light according as the depth at which the spark was produced proved greater or less. The spark shown within an ivory ball, an orange, an apple, or under the thumb, illuminates these bodies throughout. A lemon is especially suited to this experiment, flashing forth, at every spark, as a spheroid of very brilliant golden light, and a row of eggs is also brilliantly illuminated throughout, at the passage of every spark from a Leyden jar. Morgan likewise made several experiments to ascertain the influence of electricity on the animal functions. These are alluded to at p. 602, Vol. VIII of the 1855 “Britannica,” and at p. 49 of “Electricity” in the “Library of Useful Knowledge.”

This George Cadogan Morgan (1754–1798) was an English physician and also a Professor of Natural Philosophy at Hackney, in an establishment founded by his uncle, Dr. Price. His “Lectures on Electricity” appeared in Norwich during the year 1794. In the second volume he describes (pp. 225–236) “the form, noise, colours and devastation of the electric flash,” and treats (pp. 383–397) of the “relation of the electric fluid to vegetation,” alluding more particularly to the experiments of Maimbray, Nollet, Achard, Duvernier, Ingen-housz, Van Breda, Dr. Carmoy and the Abbé d’Ormoy. He likewise gives an account of the northern lights, as well as descriptions of Bennet’s movable doubler and electroscope, and of Lane’s electrometer.

REFERENCES.--Morgan’s biography in Larousse, “Dict. Universel,” Tome XI. p. 562, and in “Biog. Générale,” Tome XXXVI. p. 570; “Bibl. Britan.” An. VII. vol. ii. pp. 129, 223, and Vol. XII. p. 3.

=A.D. 1786.=--Rittenhouse (David), an American physicist and astronomer who afterward became F.R.S. and succeeded Dr. Franklin as President of the Am. Philos. Soc., publishes his theory of magnetism in a letter to John Page at Williamsburg, which is reproduced at folio 178 of Vol. II, old series, of the Transactions of the above-named Society.

“Were we called upon,” says Renwick, “to assign him a rank among the philosophers whom America has produced, we should place him, in point of scientific merit, as second to Franklin alone.”

REFERENCES.--“Trans. Am. Phil. Soc.,” Vol. II, O.S., pp. 173, 175, for Page and Rittenhouse, and Vol. III. for Rittenhouse and Jones, as well as Rittenhouse and Hopkinson, upon “Meteors and Lightning.”

=A.D. 1786.=--Galvani (Aloysio or Luigi), an Italian physician, who, at the age of twenty-five, was Professor of Anatomy at the University of Bologna, is led to the discovery of that important branch of electricity which bears his name. The manuscript giving the result of his experiments upon the Electricity of Metals is dated Sept. 20, 1786.

From papers in the “Bolognese Transactions” noted below, it would appear that he had, even before the year 1780, made many observations on the muscular contraction of frogs by electrical agency. Upon one occasion his wife happened to be holding a scalpel against the dissected legs and parts of the spine of a frog, which lay in close proximity to the conductor of an electrical machine recently charged by one of Galvani’s pupils. She noticed that whenever the dissecting knife touched the muscles they were violently convulsed, and, upon communicating the fact to her husband, he repeated and extended the experiment and found it necessary to pass the electric fluid through a metallic substance in order to develop the result originally observed. At first the frogs had been hung upon a copper hook fastened to an iron railing, but he afterward substituted an arc composed of both metals and with which he could readily produce the same results as were obtainable with an electrical machine.

Galvani also made experiments to ascertain the effect of atmospheric electricity upon the nerves of frogs. He connected the latter with rods leading to lightning conductors erected upon the roof of his house, attaching also ground wires to the legs of the animals, and found that the same convulsions appeared whenever lightning was seen and likewise when heavy storm clouds passed over the house.

The results of his many interesting observations were first made public in the celebrated work entitled “Aloysii Galvani de viribus electricitatis in motu musculari. Commentarius: cum Aldini dissertatione et notis,” which appeared during 1791–1792. Therein, he expresses the belief that the bodies of animals possess a peculiar kind of electricity by which motion is communicated through both nerve and muscle, positive electricity going to the nerve, while negative electricity goes to the muscle, and that the muscles represent the exterior and the nerves the interior of the Leyden jar, the discharge being similarly produced by the metal which communicates with both.

Galvani’s singular experiments naturally attracted everywhere the attention of philosophers, by whom they were repeated and varied, but by none were they more assiduously prosecuted than by Volta, who was then a Professor at the Pavia University, and who, as already indicated, was led by them to the discovery of the voltaic pile and of voltaic or galvanic electricity.

The announcement of Galvani’s observations was made in Germany, notably by J. F. Ackermann (“Medicinisch-chirurgische Zeitung”), by M. Er (“Physiologische Darstellung der Lebenskräfte”), by M. Smuck (“Beiträge zur weiteren Kenntniss,” etc.), and by F. A. C. Gren (“Journal der Physik,” Vols. VI, VII and VIII), while experiments were continued upon an extensive scale by the Italians F. Fontana, Carlo Francesco Bellingeri, M. Giulio and F. Rossi, as well as by Samuel T. Von Sömmering, by Wilhelm Behrends and by Karl Friedrich Kielmayer (Kielmaier), Professor of Medicine at the Tübingen University (Poggendorff, Vol. I. p. 1253). For the curious galvanic experiments of the celebrated French physician Larrey, and of Stark, Richerand, Dupuytren and Dumas, see “Bulletin des Sciences de la Société Philomathique,” 1793, Nos. 23, 24, and “Principes de Physiologie,” Vol. II. p. 312.

REFERENCES.--C. Alibert, “Eloges Historiques de Galvani, Spallanzani, Roussel et Bichat ...” Paris and Bologna, 1802–1806 (“Mém. de la Soc. d’Emul. de Paris,” Vol. IV; S. Gherardi, “Rapporto sui Manoscrotti,” Bologna, 1840, p. 19); Poggendorff, Vol. I. p. 839; Thomas Thomson, “History of the Royal Society,” London, 1812, pp. 450, etc.; Thomas Young, “Course of Lectures,” London, 1807, Vol. II; “Bolognese Transactions” for papers dated April 9, 1772, April 22, 1773 and Jan. 20, 1774; Sabine, “El. Tel.,” 1872, pp. 16–18; Knight’s “Mech. Dict.,” Vol. II. pp. 936, 937, for extract from report of Nat. Inst. of France, July 4, 1798; “Johnson’s Encyclop.,” 1877, Vol. I. p. 1510; Bakewell’s “Electricity,” p. 26; “Encyclop. Britannica,” 1855, Vol. VIII. p. 530, and Vol. XXI. pp. 609, etc.; Fahie’s “History,” etc., 1884, pp. 180–185; Phil. Trans., 1793; Miller, “History Philos. Illustrated,” London, 1849, Vol. IV. p. 333; Thomson, “Hist. of Chemistry,” Vol. II. pp. 251, 252; Matteucci, “Traité des phénomènes,” etc., Part I. p. 7; the Address of M. Gavarret made in 1848 before the Paris Medical Faculty; J. C. I. A. Creve’s treatise on Galvanism (“Jour. de la Soc. de Méd.,” Vol. XVIII. p. 216); “Mém. de la Soc. Méd. d’Emul.,” Vol. I. p. 236); Biot et Cuvier (Ann. de Ch., Vol. XXXIX. p. 247); A. Richerand (“Mém. de la Soc. Méd. d’Em.” Vol. III. p. 311); “Opus. Scelt.,” Vol. XV. p. 113; “Giornale Fis. Med.,” Vol. II. pp. 115, 131 (letter of B. Carminati); Marsiglio Landriani, “Lettera,” etc., 1776; Lettre d’un ami au Comte Prosper Albo (“Bibl. de Turin,” 1792, Vol. I. p. 261; Jour. de Phys., Tome XLI. P. 57); “Comment Bonon. Scient.,” Vol. VII. p. 363; account of the experiments made by MM. Cortambert and Gaillard, reported in “Mém. de la Soc. Méd. d’Em.,” Vol. I. pp. 232, 235; G. Klein’s “Dissert. de Métal,” etc., Maintz, 1794; Ostwald’s Klassiker, No. 52, p. 4; C. H. Wilkinson, “Elements of Galvanism,” etc., London, 1804, 2 Vols. passim; Wm. C. Wells, “Obs. on the Influence,” etc. (Phil. Trans., 1795, Pt. XI. p. 246); E. G. Robertson (An. de Ch., 1801, Vol. XXXVII. p. 132; Jour. de Paris, 10, 15 and 17 Fructidor de l’An. VIII); Paul Louis Simon, “Beschreibung neuengalvanisch,” etc., “Resultate,” etc., and “Versuche,” etc., all published in 1801 (L. W. Gilbert’s Annalen, 1801, Book V, An. de Chimie, No. 121, p. 106); L. W. Gilbert’s Book VI of the Annalen, containing the “Memoirs on Galvanism,” by J. L. Boeckmann, L. A. von Arnim, Paul Erman, M. Gruner and C. H. Pfaff; C. Dupuytren, “Faits Particuliers,” etc., 1801; J. B. Trommsdorff, “Expér. Galv.,” 1801; M. Rouppe’s letter of Aug. 28, 1801, in Van Mons’ Jour. de Ch., Vol. I. pp. 106, 108; M. Bichat (Sue, “Hist. du Galv.,” II. p. 216); A. M. Vassalli-Eandi (Jour. de Phys., Frimaire, An. X. p. 476); C. F. Hellwag and M. Jacobi fils, “Erfahrungen,” etc., 1802; M. le Comte de Pusckin’s experiments on Galvanism, made Sept. and Dec. 1801, with a colonne tournante (Sue, “Hist. du Galv.,” Vol. II. pp. 257, 258); Al. Volta, in Jour. de Leipzig, and in “Comment ... Med. gestis,” 1792; Johann Mayer, “Abh. ... Galvani, Valli, Carminati u. Volta ...” Prag, 1793); Junoblowiskiana Society (“Comment ... Med. gestis,” 1793); “Imperial Dictionary of Universal Biography,” Wm. McKenzie London, n. d., Vol. II. p. 546; M. Cortambert (“Mém ... Soc. ... d’Emul.,” I. p. 232); M. Payssé (“Jour. de la Soc. des Pharm.,” first year, p. 100); Geo. Couvier (Jour. de Physique, Vol. VII. p. 318; “Mém. des Soc. Sav. et Lit.,” Vol. I. p. 132), 1801; C. Mathieu (“Rec. de la Soc. d’Agr. ... d’Autun,” An. X. p. 21), 1802; Ponton d’Amécourt, “Exposé du Galvanisme,” Paris, 1803; Joseph Weber’s works, published in 1802–1803, 1815, 1816, and those of J. K. F. Hauff, Marburg and Leipzig, 1803, 1804; M. Curtet (Jour. de Van Mons., No. VI. p. 272; Jour. de Physique, An. XI. p. 54), 1803; William Meade (“On the origin and progress of Galvanism”), Dublin, 1805; J. C. Reil (Jour. de Van Mons., No. IV. p. 104; Sue, “Hist. du Galv.,” Vol. IV. p. 26); J. A. Heidmann (Phil. Mag., Vol. XXVIII. p. 97), 1807; Sir Richard Phillips, “Electricity and Galvanism explained ...” (Phil. Mag., Vol. LVI. p. 195), London, 1820; B. G. Sage, “Recherches ... Galvanisme”; Leopold Nobili, “Sur le courant....” Genève, 1827.

=A.D. 1786.=--Hemmer (J. J.), celebrated physician and secretary of the Meteor. Society of Mannheim, gives, in the “Transactions of the Electoral Society,” an account of what have been pronounced the most complete series of experiments ever made upon the electricity of the human body. They absolutely show that the human subject possesses no species of electrical organs which are under the regulation of the will. Of his many observations, the following are worth recording: He found that the electricity of the body is common to all ages and sexes; that its intensity and character often vary in the same body (in 2422 experiments, it was 1252 times positive, 771 times negative and 399 times imperceptible); that the electricity of the body is naturally positive, it being always so when subject to no violent exertion, and that when the body is subjected to sudden or violent motion the electricity becomes negative, the case also when the body experiences either cold or extreme lassitude.

REFERENCES.--“Encycl. Brit.,” Vol. VIII, 1855, p. 571; “Rheinische Beiträgen zur Gelehrsamkeit” for 1781, Fifth Book, pp. 428–466; Van Swinden, “Recueil,” etc., La Haye, 1784, Vols. I and II passim; “Observ. sur la Phys.,” July, 1780; _Phil. Mag._, 1799, Vol. V. pp. 1, 140; “Comment. Acad. Theod.-Palat.,” Vols. IV, V and VI of Phys.; “Mém. de l’Acad. de Mannheim,” Vol. IV; “Pfalzbayr. Beiträge” for 1782.

=A.D. 1787.=--Lomond--Lomont--(Claude Jean-Baptiste), a very capable French machinist, and “one who has a genius for invention,” is the first to introduce a successful electric telegraph consisting of but one wire. Of this the following account appears under date Oct. 16, 1787, in Arthur Young’s “Voyage Agronomique en France” (“Travels”), fourth edition, Vol. I. p. 79: “You write two or three words on a paper; he takes it with him into an adjoining room and turns a machine in a cylinder case, on the top of which is an electrometer having a pretty little ball of pith of a quill suspended by a silk thread; a brass wire connects it to a similar cylinder and electrometer in a distant apartment, and his wife, on observing the movements of the corresponding ball, writes the words which it indicates. From this it appears that he (Lomond) has made an alphabet of motions. As the length of the brass wire makes no difference in the effect, you could correspond with it at a great distance, as, for example, with a besieged city or for objects of much more importance. Whatever be the use that shall be made of it, the discovery is an admirable one.”

REFERENCES.--Ed. Highton, “Elec. Tel.,” 1852, p. 38; Sabine, “Elec. Tel.,” pp. 10–11; Shaffner, “Manual,” pp. 132, 133; Vail’s “History,” etc., p. 121; “Appleton’s Encycl.,” 1871, Vol. XV. p. 335.

=A.D. 1787.=--Brard (Cyprien Prosper), French mineralogist, first observes that some crystals of axinite (consisting mainly of silica, alumina, lime and peroxide of iron) become electric by heat.

REFERENCES.--Gmelin, article “Electricity,” etc., Vol. I. p. 319; Larousse, “Dict. Univ.,” Vol. II. p. 1205; Thomas, “Dict. of Biog.,” Vol. I. p. 429; “Enc. Brit.,” 8th ed., Vol. VIII. p. 530; Brard, “Manuel du Minéralogiste,” etc., Bordeaux Academy of Sciences Report for 1829, p. 39, and for 1838, p. 84--the latter containing M. Hatchett’s observations on one of M. Brard’s meteorolites.

=A.D. 1787.=--Haüy (Le Père René Just), native of Picardie and member of the Académie Royale des Sciences, publishes an abridgment of the doctrines of Æpinus (at A.D. 1759) under the title of “Exposition raisonnée de la Théorie de l’Électricité et du Magnétisme.” He was doubtless the first to observe that in all minerals the pyro-electric state has an important connection with the want of symmetry of the crystals, and no proof of the extent to which he directed his investigations in that line can more readily be had than by consulting general “Encyclopædia” articles relative to the pyro-electricity of boracite (borate of magnesia), of prehnite (silica, alumina and lime), of mesotype (hydrated silicate of alumina and of lime or of soda), of sphene (silica, titanic acid and lime), calamine (silicate of zinc) and of Siberian topaz.

At pp. 480, 481 of his “Outline of the Sciences,” etc., London, 1830, Dr. Thomas Thomson states:

“There is a hill of sulphate of lime, called Kalkberg, situated near Lunebourg, in the duchy of Brunswick, in which small cubic crystals are found. These cubes are white, have a specific gravity of 2·566, and are composed of two atoms of boracic acid combined with one atom of magnesia. They are distinguished among mineralogists by the name of boracite. If we examine the cubic crystals of boracite, we shall find that only four of the solid angles are complete, constituting alternate angles placed at the extremity of two opposite diagonals at the upper and lower surface of the cube. The other four solid angles are replaced by small equilateral triangles. When the boracite is heated all the perfect solid angles become charged with negative electricity, while all the angles replaced by equilateral triangles become charged with positive electricity. So that the boracite has eight poles: four positive and four negative. Those are obviously the extremities of four diagonals connecting the solid angles with each other. One extremity of each of these diagonals is charged with positive and the other extremity with negative electricity. In general, the electricity of boracite is not so strong as that of the tourmaline.” This curious law of the excitability of the boracite and of its eight poles was discovered by Haüy in 1791 (Haüy’s “Minéralogie,” 260, second edition).

Axinite, mesotype, and the silicate of zinc are also minerals which become electric when heated, and which, like the tourmaline, exhibit two opposite poles, the one positive, the other negative. It is not every crystal of axinite and mesotype which possesses this property, but such only as are unsymmetrical, that is to say, such as have extremities of different shapes. No doubt this remark applies also to the silicate of zinc; though as the crystals of that mineral are usually acicular it is not so easy to determine by observation the degree of symmetry which they may possess.

The topaz, prehnite, and the titaniferous mineral called sphene are also capable of being excited by heat, and have two opposite poles like those already mentioned.

Haüy also made the most extensive and accurate observations known upon the development of electricity in minerals by friction. Detailed lists of the different classes of minerals, as well as the conclusions arrived at through various experiments, are given in the “Encyclopedia Britannica,” Vol. VIII, 1855, pp. 538, 539, while at pp. 529 and 558 of the same work are to be found accounts of his observations on the electricity of the tourmaline, as well as a description of the different electroscopes employed in his many experiments.

REFERENCES.--Priestley, “History of Electricity,” 1767, pp. 314–326; Gmelin’s “Chemistry,” Vol. I. p. 319; Noad, “Manual,” pp. 27–31; also article “Electricity” in “Library Useful Knowledge,” pp. 3, 54, 56; M. Lister, “Collection Académique,” Tome VI; “Société Philomathique,” An. V. p. 34; An. XII. p. 191; “Mém. du Museum d’Hist. Nat.,” Vol. III; “Mém. de l’lnstitut,” An. IV. tome i., “Sciences Math. et Phys.” p. 49; “Mém. de l’Académie,” 1785, Mem. p. 206; Philosophical Magazine, Vols. XX. p. 120; XXXVIII. p. 81; Thomas Thomson, “Hist. of the Roy. Soc.,” London, 1812, pp. 180, etc.; Young’s “Lectures,” London, 1807, Vol. II; Haüy, “Traité Élémentaire de Physique,” Chap VII, “Magnetism”; Experiments of J. L. Treméry (author of “Observations sur les Aimants Elliptiques,” recorded in _Journal des Mines_, Vol. VI for 1797, also in Jour. de Phys., Vols. XLVIII and LIV) and of M. De Nelis, some of whose observations are given in the Phil. Mag., Vol. XLVIII. p. 127, and in the Jour. de Phys., Vols. LXI. p. 45; LXII. p. 150; LXIII. p. 147; LXIV. p. 130; LXVI. pp. 336, 456, as shown and illustrated at pp. 153–162 of Delaunay’s “Manuel,” etc., of 1809; “Séances de l’Acad. de Bordeaux” for 1835, giving M. Vallot’s report on the difference existing between the chalcedony and the tourmaline. Regarding the latter, consult S. Rinmann (“K. Schwed. Akad. Abh.,” XXVIII. pp. 46, 114); C. Rammelsberg, “Die Zuzam ... und Feldspaths”; Mr. Magellan’s edition of Cronstedt’s Mineralogy for Steigliz’s tourmaline; Cesare G. Pozzi, on the tourmaline; H. Von Meyer (“Archiv. ... Ges. Natural,” XIV. 3, p. 342); M. Lechman (Berlin Academy Reports); Carl Von Linné (Linnæus), “Flora Zeylanica,” Stockholm, 1747; M. Leymerie (Toulouse Acad. Reports); Brewster, “Journal” I. p. 208; J. K. Wilcke (“Vetensk. Akad. Handl.,” 1766 and 1768); Jos. Muller, “Schreiben ... Tourmaline,” Wien, 1773; F. J. Muller von Reichenstein, “Nachr. ... an Born,” Wien, 1778; H. B. de Saussure (“Jour. de Paris”), 1784; Louis Delaunay’s letter on the tourmaline, 1782; D. G. Fischer’s works, published at Mosk, 1813, 1818; J. D. Forbes (“Edin. Trans.,” Vol. XIII), 1834.

=A.D. 1787.=--Charles (Jacques Alexandre César), a singularly able French physicist and experimentalist, who became the Secretary of the Académie des Sciences, relates many of his electrical experiments in the thirtieth volume of the Journal de Physique.

He was one of the first to study and develop the theories of Franklin, who, in company with Volta, frequently attended the brilliant lectures which Charles was enabled to give in what was then considered the most complete philosophical laboratory of Europe. In many of his experiments on atmospherical electricity, Charles has been known to produce thousands of sparks, beams or flashes, which exceeded 12 feet in length and which made reports similar to those of fire-arms. The French Academy endorsed the opinion given the Minister of War by Charles to the effect that “a conductor will effectually protect a circular space whose radius is twice the length of the rod.”

Charles invented the megascope and was the first to make an ascension in a hydrogen balloon, which he did in company with M. Robert on the 1st of December (not on the 2nd of August) 1783, ten days after the first trip made by Pilatre de Rozier and Comte d’Arlandes in a Montgolfière from the Paris Bois de Boulogne.

REFERENCES.--“Biographie Générale,” Vol. IX. pp. 929–933; Larousse, “Dict. Univ.,” Vol. III. p. 1020; _Journal de Physique_ for 1791, p. 63; “Mémoires de l’Acad. des Sciences” for 1828; George Adams, “Lectures on Nat. and Exp. Philosophy,” London, 1799, Vol. III. pp. 462–464; Edin. Encycl., 1813, article “Aeronautics,” Vol. I. p. 160, “Franklin in France,” 1888, Part II. pp. 256, 270, 276–280; M. Veau Delaunay, Introduction to his “Manuel,” etc., Paris, 1809, pp. 19, 25 and 61–63; also pp. 23, 68, 92, 96, 122, 176 and 214.

=A.D. 1787.=--Mann (Théodore Augustin), Abbé, Flemish writer and antiquary, becomes perpetual secretary of the Brussels Academy of Sciences ten years after leaving the Nieuport Monastery (1777), and is charged with the duty of making meteorological observations, which are regularly transmitted to the Mannheim Academy officials, who receive similar reports regularly from different parts of Europe and publish them under the title of “Ephémérides Météorologiques.”

His many investigations made with electrical machines are embraced in the last-named publication and are also alluded to in his “Marées Aériennes,” etc., which appeared in Brussels during the year 1792.

REFERENCES.--“Biog. Générale,” Tome XXXIII. p. 231; Larousse, “Dict. Universel,” Tome X. p. 1085; Phil. Mag., Vol. IV. p. 337; “Comm. Ac. Theod. Pal.,” 1790, Vol. VI. p. 82.

=A.D. 1787.=--Bennet (Rev. Abraham), F.R.S., first describes in the Philosophical Transactions for this year, pp. 26–32, the gold-leaf electroscope which bears his name and which is considered the most sensitive and the most important of all known instruments for detecting the presence of electricity. It consists of a glass cylinder which is covered with a projecting brass cap, made flat in order to receive upon it whatever article or substance is to be electrified, and having an opening for the insertion of wires and of a metallic point to collect the electricity of the atmosphere. The interior of the cap holds a tube which carries two strips of gold leaf in lieu of the customary wires or threads, and upon two opposite sides of the interior of the cylinder are pasted two pieces of tinfoil directly facing the gold-leaf strips. The cap is turned around until the strips hang parallel to the pieces of tinfoil, so that any electricity present will cause the strips to diverge and make them strike the tinfoil, which will carry the electricity through the support of the cylinder to the ground.

This electroscope, says Wilkinson, possesses great sensibility, and through the movable coatings introduced by Mr. Pepys, very small portions of electricity are discernible. Another very excellent electroscope is formed with either extremely fine silver thread, prepared after the manner of Mr. Read, or with the minutest thread found in a bundle of very fine flax, having a little isinglass glue applied gently over it with the finger and thumb.

Of the numerous observations made by Bennet, the following interesting extract relative to the phenomenon of evaporation is taken from the Philosophical Transactions for the year 1787. “If a metal cup with a red hot coal in it be placed upon the cap of a gold leaf electroscope, a spoonful of water thrown in electrifies the cup resinously; and if a bent wire be placed in the cup with a piece of paper fastened to it to increase its surface, the vitreous electricity of the ascending column of vapour may be seen by introducing the paper into it. The experiments on the evaporation of water may be tried with more ease and certainty of success by heating the small end of a tobacco pipe and pouring water into the head, which, running down to the heated part, is suddenly expanded, and will show its electricity when projected upon the cap of the electrometer more sensibly than any other way that I have tried. If the pipe be fixed in a cloven stick and placed in the cup of one electrometer while the steam is projected upon another, it produces both electricities at once.”

Some of Mr. Bennet’s experiments with the electroscope on the electricity of sifted powders, upon the electricity of the atmosphere, etc., are recorded at pp. 564 and 566 of the “Britannica,” Vol. VIII, and at p. 56 of “Library of Useful Knowledge.”

Mr. Bennet also invented the electrical doubler, designed to increase small quantities of electricity by continually doubling them until visible in sparks or until the common electrometer indicates their presence and quality (Phil. Trans. for 1787, p. 288). It consists of three plates of brass, illustrated and explained at Fig. 9, p. 20, Vol. I of Prescott’s “Electricity and the Electric Telegraph,” 1885 edition, wherein it is stated that in forty seconds the electricity can thus, by continual duplication, be augmented five hundred thousand times. (See, for doublers, C. B. Désormes and J. N. P. Hachette, in Annales de Chimie, Vol. XLIX for 1804; J. Read (Phil. Trans. for 1794, p. 266); Sir Francis Ronalds (Edin. “Phil. Journal,” Vol. IX. pp. 323–325).)

At p. 105 of his “Rudim. Magnetism,” Snow Harris mentions the fact that, in some of his experiments, Mr. Bennet employed a magnetic needle suspended by filaments of a spider’s web as a magnetometer. In this connection, it may be said that, in the Philosophical Transactions for 1792, the assertion is made that a fine, and weakly magnetic steel wire suspended from a spider’s thread of three inches in length will admit of being twisted around eighteen thousand times and yet continue to point accurately in the meridian, so little is the thread sensible of torsion (Young’s “Course of Lectures,” 1807, Vol. II. p. 445). The use of the spider’s line had, during the year 1775, been recommended as a substitute for wires by Gregorio Fontana, who, it is said, obtained threads as fine as the eight-thousandth part of a line. In a lecture delivered at Boston, Mass., during the year 1884, Prof. Wood alluded to spiders’ threads estimated to be one two-millionths of a hair in thickness.

REFERENCES.--Bennet, “New Experiments on Electricity,” etc., Derby, 1789, and “A New Suspension of the Magnetic Needle,” etc., London, 1792; Introduction to “Electrical Researches,” by Lord Henry Cavendish; Sc. Am. Supplement, No. 647, pp. 10, 327; Noad, “Manual,” p. 27; Cavallo, “Nat. Phil.,” 1825, Vol. II. pp. 199, 216; Phil. Trans., Vol. LXXVII. pp. 26–31, 32–34, 288–296; also the abridgments by Hutton, Vol. XVI. pp. 173, 176, 282 and Vol. XVII. p. 142; Sc. American, Vol. LI. p. 19; Annales de Chimie, Vol. XLIX. p. 45; Ezekiel Walker, _Phil. Mag._ for 1813, Vol. XLI. p. 415 and Vol. XLII. pp. 161, 215, 217, 371, 476, 485; also Vol. XLIII. p. 364.

Spotted a typo or a problem in this chapter? Tell us