Elements of natural philosophy; being an experimental introduction to ... the physical sciences

Front matter

Wellcome Library

WORKS

ON

I. A Manual For The Use Of Students Preparing

FOR EXAMINATION AT APOTHECARIES’ HALL. Ninth Edition. 12mo. cloth, 8s. 6d.

ii.

A MANUAL FOR THE COLLEGE OF SURGEONS; 12mo. |

cloth, 12s. 6d.

ILL

GREGORY’S CONSPECTUS MEDICINE THEORETICAL

The First Part, containing the Original Text, with an Ordo Verborum and Literal Translation. 12mo. cloth, 10s.

IV.

THE FIRST FOUR BOOKS OF CELSUS. Containing the

Text, Ordo Yerborum, and Translation. 12mo. cloth, 8s.

The above two works comprise the entire Latin Classics required for Examination at Apothecaries’ Hall.

v.

FIRST LINES FOR CHEMISTS AND DRUGGISTS PREPAR- ING FOR EXAMINATION AT THE PHARMACEUTICAL SOCIETY. 1 8mo. cloth, 3s. 6d.

MEL OTTOOTttM PTUBOCATIOHSo 7

MR. SHAW, M.R.C.S.

ASSISTANT-APOTHECARY TO ST. BARTHOLOMEW’S HOSPITAL.

THE MEDICAL BEMEMBBANCEB ; OE, BOOK

OF EMERGENCIES: in which are concisely pointed out the Immediate Remedies to he adopted in the First Moments of Danger from Poisoning, Drowning, Apoplexy, Burns, and other Accidents; with the Tests for the Principal Poisons, and other useful Information. Second Edition. 32mo. cloth, 2s. 6c?.

J. STEPHENSON, M.D., 8c J. M. CHURCHILL, F.L.S.

MEDICAL BOTANY ; OR, ILLUSTRATIONS AND

DESCRIPTIONS OF THE MEDICINAL PLANTS OF THE PHARMACOPCEIAS; comprising a popular and scientific Account of Poisonous Vegetables indigenous to Great Britain. New Edition, edited by GILBERT BURNETT, F.L.S., Professor of Botany in King’s College. In three handsome royal 8vo. volumes, illustrated by Two Hundred Engravings, beautifully drawn and coloured from nature, cloth lettered, Six Guineas.

“ The most complete and comprehensive work on Medical Botany.” — Pharmaceutical Journal.

ALFRED S. TAYLOR,

LECTURER ON MEDICAL JURISPRUDENCE AND CHEMISTRY AT GUY’S HOSPITAL.

A MANUAL OE MEDICAL JUBISPBUDENCE AND

TOXICOLOGY. Fcap. 8vo. cloth, 12 s.6d.

“ We have the pleasure of meeting the accumulated stores of science and experience on this branch of knowledge, condensed and made accessible in this admirable volume. It is, in fact, not only the fullest and most satisfactory book we have ever consulted on the subject, but it is also one of the most masterly works we have ever perused.” — Medical Gazette.

“ The most elaborate and complete work that has yet appeared. It contains an immense quantity of cases, lately tried, which entitles it to be considered now what Beck was in its day.” — Dublin Medical Journal.

“ Mr. Taylor possesses the happy art of expressing himself on a scientific topic in intelligible language. The size of his Manual fits it to be a circuit companion. It is one of the most beautiful specimens of typography we ever had the pleasure — and it is a pleasure — of perusing.” — Law Times.

BY A PRACTISING PHYSICIAN.

THE PBESCBIBEB’S PIIABMACOPCEIA ; containing

all the Medicines in the London Pharmacopoeia, arranged in Classes according to their Action, with their Composition and Doses. Third Edition. 32mo. cloth, 2s. Qd.

“ Never was half-a-crown better spent than in the purchase of this ‘ Thesaurus Medicaminum.’ This little work, with our visiting-book and stethoscope, are our daily companions in the carriage.” — Dr. Johnson’’ s Review.

msl croicmrs ptubocationi

PROFESSOR OF THE PRACTICE OF MEDICINE, UNIVERSITY COLLEGE, LONDON.

PRINCIPLES OF MEDICINE ; comprehending General

Pathology and Therapeutics. Deray 8vo. cloth, 12s.

“The entire work is one of no ordinary ability, and well sustains the reputation of the author.” — Provincial Medical Journal.

“ We have no hesitation in asserting, that the reader will derive greater pleasure, and more useful practical knowledge, from this book, than from any other treatise on the subject, that we are acquainted with. Dr. Williams has already earned for himself a lasting fame, by his work on Diseases of the Chest ; and that must, if possible, be increased still more by his “Principles of Medicine.” — Dublin Medical Journal.

BY THE SAME AUTHOR.

THE PATHOLOGY AND DIAGNOSIS OE DISEASES

OF THE CHEST; illustrated chiefly by a Rational Exposition of their Physical Signs. Fourth Edition, with much important new matter. Plates. 8vo. cloth, 10s. 6d.

“ The fact that a fourth edition is called for is a very good argument in favour of any book. But this was not necessary in the case of Dr. Williams ; it was well known to the profession as one of the best manuals of diseases of the chest we possess.” — Dublin Medical Journal.

MR. ERASMUS WILSON.

DISEASES OE THE SKIN ; a Practical and Theoretical

Treatise on the DIAGNOSIS, PATHOLOGY, and TREATMENT of CUTANEOUS DISEASES, arranged according to a Natural System of Classification, and preceded by an Outline of the Anatomy and Physiology of the Skin. 8vo. cloth, 10s. 6d.

“ We have now reached the conclusion of the volume, and our perusal has been both agreeable and instructive. The book is not written for a day, but for an age, the style is good and precise, the language well selected, and the information which it contains, genuine and copious. We think it adapted to cast a new light on the pathology and treatment of diseases on the skin, and to form an admirable guide to the medical practitioner, to whom and to the student we warmly recommend it.” — Dr. Johnson’s Review.

BY THE SAME AUTHOR.

THE ANATOMIST’S VADE-MECUM; A SYSTEM

OF HUMAN ANATOMY. With One Hundred and Sixty-eight Illustrations on Wood. Third Edition. Fcap. 8vo. cloth, 12s. 6d.

“Asa satisfactory proof that the praise we bestowed on the first edition of this work was not unmerited, we may observe it has been equally well thought of in foreign countries, having been reprinted in the United States and in Germany. In every respect, this work, as an anatomical guide for the student and the practitioner, merits our warmest and most decided praise.” — Medical Gazette.

“ This is probably the prettiest medical book ever published, and we believe its intrinsic merits are in keeping with its exterior advantages, having examined it sufficiently to satisfy us that it may be recommended to the student as no less distinguished by its accuracy and clearness of description than by its typographical elegance. The wood-cuts are exquisite.” — British and Foreign Medical Review.

ELEMENTS ui1

NATURAL PHILOSOPHY.

ELEMENTS

OF

NATURAL PHILOSOPHY;

BEING AN

EXPERIMENTAL INTRODUCTION

TO THE

STUDY OF THE PHYSICAL SCIENCES.

BY

GOLDING BIRD, A.M, M.D., F.L.S.

MEMBER OF THE ROYAL COLLEGE OF PHYSFCIANS;

LATE PRESIDENT OF THE WESTMINSTER MEDICAL SOCIETY ; CORRESPONDING MEMBER OF THE PHILOSOPHICAL INSTITUTE OF BALE, OF THE PHILOSOPHICAL SOCIETY OF ST. ANDREWS,

OF THE MEDICAL SOCIETY OF HAMBURGH, ETC. ; ASSISTANT-PHYSICIAN TO, AND LECTURER ON MATERIA MEDICA AT,

guy’s HOSPITAL.

LONDON :

MDCCCXLIY.

Newton. Princip. Math. Phil., lib. iii., Schol. Glen.

HISTORICAL.

medical

STRAND.

TO THE

STUDENTS OF GUY’S HOSPITAL,

THIS EDITION OF A WORK, ORIGINALLY

WRITTEN FOR THEIR USE,

IS

DEDICATED,

WITH SINCERE WISHES FOR THEIR SUCCESS IN THE HONOURABLE AND ARDUOUS CAREER THEY HAVE COMMENCED,

Gays Hospital, Oct. 1843.

VI

Preface

preparatory to his entering upon the study of larger, and more elaborate works. With this view it has been written; and as the great difficulty experienced in executing this task has arisen from the necessity of knowing, not what to insert, but what to omit, whenever a doubt has arisen on this point, it has been determined by a reference to the amount of knowledge required of the student, by the different English and Scottish medical boards.

A work of this kind I had long ago projected, in consequence of not being acquainted with any in the English language, to which I could refer the students attending the lectures on physics, annually delivered at Guy’s Hospital; although I had hitherto shrunk from the task, hoping that a production, so much required by the medical and general student, would have emanated from some more able writer.

As an apology for the arrangement followed in this volume, it must be observed that utility and extreme simplicity, rather than elegance of style, were sought for, and every other object has been sacrificed to obtain this end. The division into numbered paragraphs was adopted, as every chapter would thus become a kind of running commentary on the others, and would, moreover, facilitate reference to distinct subjects in the Analytical Index.

I regret, as every writer on so extensive a series of subjects must do, the impossibility of doing justice to every labourer in the field of philosophic inquiry, by referring each discovery to its author : as far as this could without circumlocution be effected, it has been done. For discoveries of longer date, as they have become the common property of science, there needs no apology for not in every case mentioning the name of their authors in a strictly elementary work.

I have been greatly indebted to several writers in the French and German languages, for many suggestions and illustrations, of which I have never hesitated to avail myself whenever they appeared to divest any subject of obscurity.

PREFACE.

Vll or to add to its interest. To the “ Precis de Physique” of Biot, the “Elemens de Physique” of Pouillet, the “Traitede Physique” of Hauy, the “Positions de Physique” of Quetelet, and the “ Grundriss der Experimental- Physik” of Kastner, I have been peculiarly indebted for several illustrations, some of which have not, I believe, previously appeared in an English dress.

Having thus explained the object and unpretending character of this volume, I trust enough has been said to blunt the edge of criticism, should such, perchance, be levelled against it. The critic himself, I would beg to remind of the celebrated observation of Horace —

Those readers who desireTurther information on the subjects treated of in this work, and have not the assistance derived from attendance on lectures, may, if only a popular acquaintance with them be required, refer to the very elegant, although as yet unfinished, “ Elements of Physics” of Dr. Arnott, or to Sir David Brewster’s edition of “ Euler s Letters to a German Princess.” Those who require a more profound acquaintance with these important subjects, should consult the books referred to in the body of this volume, as well as to the treatises published by the Society for the Diffusion of Useful Knowledge. The series of Essays written by the professors of King’s College, London, now in the course of publication, will also furnish most valuable comments on this, and other elementary works.

In the execution of this task, I have experienced but one source of regret, and one which every person engaged in the duties of a laborious profession must feel, when called upon to write on a series of subjects, to a certain extent distinct

Vlll

PREFACE.

from his immediate duties, and requiring for their elucidation a much greater amount of time, than his more onerous engagements will allow him to devote to them ; — a source of regret arises from the feeling, that a work of this kind had not appeared from the pen of one better fitted to the task, than of him who now offers it to public notice.

October , 1839.

PREFACE

TO THE SECOND EDITION.

In this edition I have endeavoured to make such improvements as shall render it worthy of the patronage bestowed upon the first, which has been for some time out of print.

The principal additions made to this work consist in the introduction of three chapters, embracing the subjects of thermotics and the chemical action of light. The chapters on electronomical decomposition, and part of those on polarized light, have been re-written. I have endeavoured to elucidate as much as possible whatever appeared obscure, so as to facilitate the labours of the student. To assist which about eighty new wood-cuts have been added.

Myddelton Square,

ANALYTICAL TABLE OE CONTENTS.

PAGE

Preliminary discourse ----- xxxii

Division of the subject into different branches - - xxxiii

Newton’s ruies for philosophizing ... - xxxv

Question of finite divisibility ... - xxxvii

Conversion of the solid, liquid, and gaseous states into each other xxxix Effects of the vibration of ponderable matter - - xl

Density and elasticity of imponderable matter - - xli

Effects of the undulations of imponderable matter - - xliv

( The following figures refer to the numbered paragraphs, and

not to the pages.)

Chapter I. Statics

General Properties of Atoms and' Masses of Matter.

PAK.

Finite divisibility of matter ----- 1

Impenetrability, extension, and figure of atoms - - 6

Chemical and physical analysis - - - - 7

Attraction and repulsion ; solids, fluids, and gases - - 9

Divisibility or extension of masses - - - -11

Flexibility - - - - - - - 12

Tenacity; table of tenacity of metals - - - 13

Brittleness - - - - - - - 14

Elasticity - - - - - - - 15

XU

Chapter II. Statics

Attractive Forces exerted between Masses.

PAR.

Forms of attraction - - - - - - 17

Law of attraction - - - - - - 18

Cohesion .... - - 19

Table of, as exerted between metals and mercury - - 21

Capillary attraction and repulsion .... 22-23

Capillary attraction in tubes - - - - - 23

Capillary attraction between plates - - - - 24

Elevation of fluids in capillary tubes - - - - 25

Apparent attraction and repulsion of bodies, floating on water 28 Endosmose and exosmose ----- 29-30

Diffusion of gases - - - - - - 31

Direction of the attraction of gravitation - - - 33

Lateral gravitation - - - - - - 35

All bodies fall with equal velocity - - - - 36

Elevation of light bodies produced by gravitation - - 37

Figure of the planets produced by gravitation - - 38

Diminution of weight at a distance from the earth - - 39

Centres of gravity, of inertia, of parallel forces - - 40

Determination of the centres of gravity of bodies - - 41-44

Action of gravity on bodies of unequal density - - 44

Conditions of state, unstable, and indifferent equilibrium - 45-47

Chapter III. Dynamics

Bodies in motion, or general Dynamics.

Species of motion - - - - - - 48

Force necessary to produce motion - - - - 49

First law of motion, causes checking motion - - - 50

Consequences of this Law ; centrifugal force - - - 51

Figure of the earth affected by centrifugal force - - 53

Second law of motion ----- 54

Third law of motion ; action and reaction - - - 55

Reflection of motion ; equality of angles of incidence and reflection ------ 56

Action of two equal forces on a moving body - - - 57

Action of two unequal forces - - - - 58

Action of several forces on a body - - - - 59

TABLE OF CONTENTS. Xlll

PAR.

Resolution and composition of motion - ’ - - 60

Illustrations of the action of several forces on bodies - - 62

Velocities of moving bodies - - - - 63

Chapter IV. Dynamics

Effects of Gravitation.

Accelerated motion produced by gravity - - - 64

Velocity and rate of motion of falling bodies - - - 65

Law of increase of velocity of falling bodies - - 66

Simple formulae, for discovering the velocity of falling bodies - 67

Formulae for discovering the velocity, time, and spaee described 68

Laws of bodies projected vertically upwards or downv/ards - 69

Motion of bodies in parabolic curves ; projectiles - - 70

Motion of bodies on inclined planes - - - - 71

Resistance of media - - - - - - 72

Rotation of moving bodies on their axes - - - 73

Rotation round the shortest axes - - - - 74

Case of moving bodies revolving round vertical axes - - 75

Percussion and collision, velocity before and after - - 78

Effects of collision on perfectly elastic bodies - - - 79

Collision of elastic and hard bodies - - - 80

Collision of freely suspended bodies - - - - 82

Velocity of bodies falling in curved paths - - 83

Pendulum, oscillations of bodies the effect of gravity - 84

Ratio between the length of pendula and time of oscillation - 85

Exception to the law of isochronism in large arcs - 86

Determination of the figure of the earth by the pendulum - 87

Formulae for intensity of gravity in different parts of the earth 88

Length of the second’s pendulum in different parts of the earth 90

Centres of oscillation and percussion - - - 92

Compensating or invariable pendulum - - 93

Chapter V. Mechanics

Theoretical Action of the Simple Machines.

Exchange of time for power - - - - 95

Centre of parallel forces - - - - - 96

XIV

PAR.

Theory of the lever and balance 97

Ratio of power to resistance - - - - 98

Weight of bodies determined by incorrect balances - - 99

Ratio of velocity of the power and resistance - - 100

Different modifications of levers - - - - 102

General formulae of equilibrium with the lever - - 104

Wheel and axle - - - - - - 105

Fixed pulley - - - - - 106

Simple moveable pulley - - - - 107

Compound system of pulleys - - - - 108

Formulae for equilibrium with the pulley - - - 110

Inclined plane - - - - - 111

Theoretical action of the plane - - - - 112

Friction, as an obstacle in mechanics - - - 116

Existence of levers in the animal frame - - - 117

Simple pulleys, present in animal structures - - - 119

Presence of the wedge in the skeleton of ichthyosaurus - 120

Chapter VI. Hydrostatics

Phenomena of Fluids at Rest.

General properties of fluid matter - - - - 121

Elasticity of fluids - - - - - 122

Compressibility of fluids - - - - - 123

Law of equality of pressure - - - - 124

Law of fluid equilibrium - - - - - 126

Fluid pressures vary with the depth - - - 128

Formulae for fluid pressure - - - - 129

Consequences of the law of fluid pressure - - - 130

Upward pressure of fluids - - - - 131

Lateral pressure of fluids - - - - - 133

Centre of fluid pressure - - - - - 135

Equilibrium of fluids in communicating vessels - - 136

of solids immersed in fluids - - - 138

Principle of Archimedes explained - - - - 139

Specific gravity, found by the principle of Archimedes - 140

of solids denser than water - - 141

lighter than water - - 142

soluble in water - - - 143

of fluids ----- 144

Hydrometer, areometer, or gravimeter - - - 146

TABLE OF CONTENTS. XV

PAR.

Specific gravity of water at different temperatures - - 146

of gases and vapours - - - 147

Determination of the absolute weights of given bulks of bodies 148 Table of specific gravities of solids, liquids, and gases.

Chapter VII. Pneumo-statics

Phenomena of Gases at Rest,

Composition of atmospheric air - - - - . 149

Question of the finite extent of the atmosphere - - 150

Weight and elasticity of the air - - - 151

Pressure of the atmosphere illustrated - - - 152

Water barometer ------ 143-4

Mercurial barometer - - - - - 155

Indications affected by heat and capillarity - - 156

Mean diurnal height of the barometer - - 157

Determination of heights by the barometer - - - 158

Explanation of the law of Mariotte - - - - 159

Pressure of the atmosphere upon a given surface - - 160

Exhausting syringe and air-pump - - - - 161

Condensing syringe - - - - - - 1 62

Experiments illustrating elasticity and pressure of the air - 163

Chapter VIII. Hydro-dynamics

Phenomena of Fluids in Motion.

Conditions necessary for the flowing of fluids from vessels - 164

Theorem of Torricelli - - - - - 165

General property of fluid currents - - - - 166

Lateral reaction of currents - - - - - 1 6 <

Ratio between velocity of fluids and diameter of channels - 1 68

Theoretical action of fountains and jets d’eau - - 169

Friction existing between fluids and solids - - - 1 70

Bemouilli’s and Barry’s experiments in illustration - - 171

Aerial fluids escaping from containing vessels - - 172

Apparent attraction of bodies by aerial currents - - 172

Different forms of pumps - - - - - 175

Stomach-pump, and Read’s lung-pump - - - 17/

Action of the syphon - - - - - 178

XVI

PAR.

Wirtemberg syphon, Tantalus’s cup - - - 179

Hiero’s fountain - - - - - - 180

Bramah’s hydraulic press . - - - - 181

Chapter IX. Acoustics

Sonorous Vibrations of Ponderable Bodies, or Sound.

Difference between tones and noises - - - 182

Diffusion of sonorous vibrations - - - - 183

Checked unless a conducting medium be present - - 184

Sounds varying in intensity with the density of the air - 185

Law of intensity of sound - ~ - - - 186

Circumstances modifying this law - - - - 1 87

Communication of sonorous vibrations - - - 188

Waves of sound capable of passing each other - - 189

Velocity of sound - - - - - - 190

Calculation of distances by sound - - - - 191

Conducting power of bodies for sound - - - 192

Existence of acoustic shadows - - - - 193

Interference of sonorous undulations - - - 194-5

Passage of sonorous waves through mixed media - - 196-7

Reflection of sound - - - - - - 198

Cause of echo ... - - - . 199

Reflection of sound by curved surfaces - - - 200

Transverse vibrations - 201

Planes in which cords vibrate .... 202

Musical notes ------ 203

Comparative view of vibrations producing notes - - 204

Musical discords and concords .... 205-6

Nodal lines and points ..... 207

Vibrations of fixed rods ..... 208

Vibrations of columns of air - - - - 209

Acoustic figures on vibrating plates - - - - 210

Explanation of the cause producing them - - - 210

Strehlke’s acoustic figures - - - - - 211

Sonorous vibrations of heated metals - - - 212

Chapter X. Magnetism

General Properties of Magnets.

Natural and artificial magnets - - - 213

Arrangement of iron-filings in curved lines - - - 214

TABLE OF CONTENTS. XVII

PAR.

Magnetic poles - - - - - 215

Magnetical attraction and repulsion - - - - 216

Induction of magnetism in iron - - - - 217

Result of the fracture of magnets - - - - 219

Conventional theory of magnetism - 220

Austral and boreal fluids - 221

Compass needle ------ 223

Magnetic meridian ; declination of the needle - - 225

Magnetic equator ; inclination or dip of the needle - - 226

Gradual change in magnetic variations - - - 228

Diurnal variation of the needle - 229

Accidental perturbations of the needle - - - 230

Explanation of the directive force of the earth - - 231

Consecutive magnetic poles - - - - - 232

Excitation of magnetism by induction - - - 233

Different processes for 234

Horse-shoe magnets - - - - - - 235

Coercing force of metals ..... 236

Magnetic intensity of nickel .... 237

Magnetic intensity of the earth - - - - 238

Computation of the earth’s magnetic force by oscillations - 239

Polar properties of non-metallic substances - - - 240

Chapter XI. Electricity

Primary Phenomena.

Excitation of electricity by friction - 241

Electrical attraction and repulsion ... - 242-3

Non-conducting idio-electric, and conducting anelectric bodies 244-5

Insulation ------- 246

Naturally combined state of the two electric fluids - - 247

Electroscopes ------ 248-50

Coulomb’s tonsion electrometer - - - - 251

Table of excited electrics - - - - - 252

Development of electricity by pressure and contact - - 253

Excitation of electricity in tourmaline and zeolite by heat - 254

Electric light and spark - - - - - 255

Superficial distribution of free electricity - - - 256-7

Decomposition of the combined electricities by induction - 258-9

Dielectrics, and inductive capacity - - - - 261

Induction, an action between contiguous particles - - 262

Constant occurrence of induction in electric phenomena - 263

Repulsion an effect of induction .... 264

c

PAR.

Electrophorus - .... 265-6

Difference between quantity and tension - - - 267

Influence of points and terminal surfaces on induction - 268

Primary laws of electro-statics - - - 269

Chapter XII. Electricity

Consequences of Induction.

Invention of the electric machine - - - 270

Description of the cylindric machine - - - 271

Plate electric machine - - - - - 272

Mode of exciting electricity by the machine - - - 273

Source of electricity in the prime conductor - - 274

Use of amalgams, and sulphuret of tin, in aiding the excitation 275 Positive and negative sparks, the effects of discharge - - 276

Pencil and star of electric light - - - - 277

Experiments illustrating electric discharge - - - 278

Induction and discharge in rarefied air - - - 279

Use of Lane’s discharging electrometer - - 280

Electric state of bodies connected with the machine - - 281

Calorific effects of electric discharge - 282

Experiments illustrating electric attraction and repulsion - 283

Development of currents of air, by induction from points - 284

Mechanical effects of electric discharge - - - 285

Luminous discharge in different media - - - 286

Conductive, disrupture, convective discharges - - 287