A treatise on the diseases of the nervous system

Front matter

LIBRARY OF CONGRESS.

Shelft/i

UNITED STATES OF AMERICA.

Dedication To Sixth Edition, 1876

I dedicate this volume to my dear friend S. Weir Mitchell, M. D., of Philadelphia, not only because he is my friend and fellow-laborer of twenty years' standing, but because his acquirements as a physician, and especially a neurologist, are such as to place him among the first of those who work in the most important department of medical science.

PEEFACE.

I have taken the occasion of an eighth edition of this work being called for, to revise it thoroughly, to make several changes, and to add a section on " Certain Obscure Diseases of the Nervous System."

Preface To Seventh Edition

The first edition of this work was published in 1871, and in the preface I then wrote :

" In the following work I have endeavored to present a Treatise on Diseases of the Nervous System, which, without being superficial, would be concise and explicit, and which, while making no claim to being exhaustive, would nevertheless be sufficiently complete for the instruction and guidance of those who might be disposed to seek information from its pages. How far I have been successful will soon be determined by the judgment of those more competent than myself to form an unbiased opinion.

" One feature I may, however, with justice claim for this work, and that is, that it rests to a great extent on my own observation and experience, and is therefore no mere compilation. The reader will readily perceive that I have views of my own on every disease considered, and that I have not hesitated to express them."

The work remained without essential change till the sixth edition, published in 1876. It was then entirely remodeled and greatly enlarged.

This, the seventh edition, has also received extensive additions.

PREFACE. 7

Among the chief of these is a considerable amplification of the chaptei on cerebral congestion, the introduction of a chapter on myxoedema, of others on syphilis of the brain, the spinal cord, and the nerves ; on the symptomatology of cerebral and cerebellar lesions, and a new section on diseases of the sympathetic nervous system. Material additions have also been made to the chapters on locomotor ataxia, progressive facial atrophy, chorea, epilepsy, neuralgia, and to many others to less extent. I have also added to the chapters on the symptomatology of cerebral and cerebellar lesions a translation of the Diagnostic Points given by Nothnagel in his remarkable work on the " Topical Diagnosis of Brain Diseases."

For much of the new matter I am indebted to Dr. Labadie- Lagrave, the accomplished editor and translator of the French edition of this work, published in Paris in 1879. The chapters on nervous syphilis, on the symptomatology of cerebral lesions, and on the pathology of the sympathetic nerve, are, except as regards the matter included within brackets, literal translations of his articles on these subjects.

I have omitted from this edition the chapters on insanity, and this mainly for the reason that I am now engaged in the preparation of a special treatise on that important subject, in which the physiology and pathology of the mind will receive much fuller consideration than could be given in a book combining the whole subject of neurological medicine. Notwithstanding this omission, the present edition contains about forty more pages than the last.

An Italian translation, under the editorial supervision of Professor Diodato Borrelli, Professor of Pathology and Clinical Medicine in the Royal University at Naples, is now going through the press.

8 PREFACE.

It would be affectation to say that the evidences which have been given, both at home and abroad, of the appreciation of my work, have not been a source of gratification. It will be my effort to show in the future that the favor awarded to my endeavors to bring the subject of neurological medicine before the profession and students is not disregarded.

43 West Fifty-fourth Street, New Tork, May 1, 1881.

Contents

The Instruments and Apparatus employed in the Diagnosis and Treatment of Diseases of the Nervous System.

PAGE

SECTIOS I.

Chap I.— Ii.- III

IV.-

VI.-

VII.-

VIII.-

IX.-

XI.-

D IS EASES OF THE BRAIX.

Active Cerebral Congestion. — Passive Cerebral Congestion. Cerebral Anaemia, . . . . . . .71

Pachymeningitis and Hematoma of the Dura Mater. -Partial Cerebral Anemia from Obliteration of Cerebral

Blood-Vessels, . . ... . . 132

Thrombosis of Cerebral Arteries. — Embolism of Cerebral Arteries. — Thrombosis of Cerebral Veins and Sinuses. — Embolism and Thrombosis of the Cerebral Capillaries.

-Cerebral Softening, . . ■ . . ,161

Chronic Verticalar Meningitis. — Chronic Basilar Meningitis. -Tubercular Cerebral Meningitis, .... 261

Cerebria.

10 CONTENTS.

CHAP. PAGE

XII.— -Diffused Ceeebeal Soleeosis, . . . 281

XIII. — Multiple Ceeebeal Scleeosis, ..... 292

XIV. — Tumoes of the Bealn, ..... 308

XVII. — Ceeebeal Syphilis, ...... 342

Anatomical Lesions. — Etiology. — General Symptomatology. XVIII. — Symptomatology of Ceeebeal Lesions, . . . 351

Cortical Paralysis. — Paralysis consecutive to Central Lesions of the Hemispheres. — Lesions of the Tubercula Quadrigemina. — Oculo- Pupillary Troubles. — Lesions of the Optic Tracts. — Lesions of the Cerebral and Cerebellar Peduncles.

XIX. — Symptomatology of Ceeebellae Diseases, . . . 372

Tumors of the Cerebellum. — Haemorrhages of the Cerebellum. — Nothnagel's Diagnostic Points.

Section II. Diseases Of Tee Spinal Cord

I. — Spinal Congestion, . . . . . . 392

II. — Spinal Anaemia, ....... 399

Anaemia of the Posterior Columns. — Anaemia of the Antero-Lateral Columns.

III. — Spinal H^moeehage — Spinal Meningeal H^emoeehage, . 432

IV. — Spinal Meningitis, . , . . . . . 439

Acute Spinal Meningitis. — Chronic Spinal Meningitis. V. — The Inflammations of the Spinal Coed, . . . . 455

Acute Myelitis. — Infantile Spinal Paralysis. — Spinal Paralysis of Adults. — Pseudo-Hypertrophic Spinal Paralysis. — Glosso-Labio- Laryngeal Paralysis. — Progressive Muscular Atrophy. — Progressive Facial Atrophy. — Tetanus. — Sclerosis of the Columns of Tiirck. — Primary Symmetrical Lateral Sclerosis. — Amyotrophic Lateral Spinal Sclerosis. — Progressive Locomotor Ataxia. — Sclerosis of the Columns of Goll. — Disseminated Inflammation of the Spinal Cord. — Secondary Inflammation and Degeneration of the Spinal Cord.

CONTENTS. 11

CHAP. PAGE

VI. — Non- Inflammatory Softening of the Spinal Coed, . 649

VII. — Tumors of the Spinal Cord, ..... 654

VIII. — Syphilis of the Spinal Cord and its Membranes, . . 661

Section III. Cerebro-spin Al Diseases

III. — Convulsive Tremor, ...... 720

VI. — Hysteroid Affections, ...... 765

Catalepsy — Ecstasy. — Hystero-Epilepsy.

VII. — Multiple Cerebro-Spinal Sclerosis, .... 793

VIII.— Paralysis Agitans, ...... 804

IX. — Anapeiratio Paralysis, . . . . . . 807

X. — Exophthalmic Goitre, ...... 812

Section IV. Diseases Of The Peripheral Nervous System

I. — Neural Congestion, ...... 822

II. — Acute Neuritis, ....... 825

III. — Chronic Neuritis — Neural Sclerosis — Neural Atrophy, . 828

IV. — Tumors of Nerves, . . . . . . 831

V. — Neural Paralysis . . . . . . . 832

Facial Paralysis. — Paralysis of Third Nerve.

VI. — Neural Spasm, ....... 842

Facial Spasm. — Torticollis.

VII. — Neural Anesthesia, . . . . . . 845

Anaesthesia of Cutaneous Nerves. — Anaesthesia of the Fifth Pair. VIII. — Neural Hyperesthesia (Neuralgia), . . . .819

Neuralgia of the Fifth Pair of Nerves. — Cervico-Occipital Neuralgia. — Cervico-Brachial Neuralgia. — Dorso-Intercostal Neuralgia. — LumboAbdominal Neuralgia. — Crural Neuralgia. — Sciatica.

IX. — Syphilis of the Peripheral Nervous System, . . . 862

12 CONTENTS.

Section V. Diseases Of The Sympathetic Nervous System

CHAP. PAGE

I. — Pathology of the Ceevical Sympathetic, . . . 864

II. — Neuroses of the Cervical Sympathetic, .... 868

Migraine, or Ilcmicrania.

III. — Pathology of the Thoracic Sympathetic, . . . 876

IV. — Pathology of the Abdominal Sympathetic, . . . 878

Symmetrical Gangrene of the Extremities.

Section VII. Certain Obscure Diseases Of The Nervous System

II.— Thomsen's Disease, ...... 927

III. — MlRYACHIT AND KlNDRED AFFECTIONS, .... 931

LIST OF ILLTTSTKATKXNS.

FIG.

PAGE

1. Cephalohemometer, ....

Hammond, .

. 20

2. J^STHESIOMETER, ....

.

3. Lombard's Differential Calorimeter, .

a

. 24

4. Lombard's Thermo-Electric Pile, .

a

5. Dynamometer, .....

Mathicu,

. 26

6. DYNAMOGRAPH, ....

it

7. Duchenne's Trocar, ....

Hammond, .

. 28

8. Stohrer's Battery, ....

9. Three Cells in situ, ....

u

. 30

10 Miliary Aneurism of Brain,

Bouchard,

11. " " " ...

Hammond, .

. 107

12. Atheromatous Artery of Brain,

13. Diagram explanatory of Paralysis in Cases of

Cerebral Hemorrhage, ....

a

. 113

14. Diagram explanatory of Crossed Paralysis, a

15. Cerebral Arterial Thrombosis,

.

Hcubner,

. 140

16. Cerebral Capillary Embolism, .

Virchow,

.

u

. 158

18. Cerebral Convolutions ....

.

Broca,

Hammond, .

. 214

20. Dynamographic Tracing of Patient affected with Mul-

tiple Cerebral Sclerosis, .

21. Dynamographic Tracing of Patient affected with Mul-

tiple Cerebral Sclerosis,

22. Malignant Tumor of Brain, .

23. Aneurysmal Tumor of Brain,

24. Hand of Patient with Athetosis,

25. " " after Photograph from Dr. Hubbard,

26. Hand of Patient with Myxcedema,

27. Portrait of Patient with Myxcedema,

" . . 340

LIST OF ILLUSTRATIONS.

28. Motor Cerebral Centres in Man,

29. Cerebral Lesion, .....

30. Cerebral Lesion, .....

31. Internal Capsule, External Face,

32. Internal Capsule, Internal Face,

33. Diagram of, explaining Phenomena op Lateral Hemio-

pia and Crossed Amblyopia, page Labadie-Lagrave, . 353 Landouzy, Labadie- Lagrave, . 356 Landouzy, Labadie- Lagrave, . . 355 Labadie-Lagrave, . 362 " " . 363

Charcot and Labadie- Zagravc, . .370

37. 38.

40. 41.

57. 58.

59. 60. 61. 62. 63. 64.

Patient with Probable Atrophy and Sclerosis of Cerebellum, ......

Morbid Anatomy in Cervical Pachymmeningitis, . Deformity caused by Cervical Pachymeningitis, Deformity caused by Chronic Spinal Meningitis, Spinal Cord in Infantile Spinal Paralysis, .

Altered Nerve-Cells of Cord in Infantile SriNAL Paralysis, . .

Muscle in Infantile Spinal Paralysis,

Atrophy of Muscles in Spinal Paralysis of Adults,

a a u u a a a a

Patient with Pseudo-Hypertrophic Spinal Paralysis,

Glosso-Labio-Laryngeal Paralysis, Writing of Patient affected with Glosso-Labio-Laryngeal Paralysis, .

Glosso-Labio-Laryngeal Paralysis,

Spinal Cord in Glosso-Labio-Laryngeal Paralysis, Progressive Facial Atrophy,

J°ff r °y>

. 444

Hammond, .

. 452 a

. 473 u

<t

. 476

. 477 a a

. 478 u

. 483 u u

. 493

.

u

. 507 u

<t

. 510 a

. 520 u u

. 523 a a

. 535

Duchenne,

Friedreich, .

. 538

Duchenne,

. 552

LIST OF ILLUSTRATIONS.

FIG.

65. 66. 67.

74. 75. 76.

77. 78.

81. 82.

96. 97.

Muscular Fibre in Progressive Facial Atrophy (Longitudinal Section — normal),

Muscular Fibre in Progressive Facial Atrophy (Longitudinal Section — abnormal),

Muscular Tissue in Progressive Facial Atrophy (Transverse Section — normal),

Muscular Tissue in Progressive Facial Atrophy (Transverse Section — abnormal),

Diagram explanatory of Anaesthesia in Lesions op Cord, . .......

Section of Spinal Cord in Sclerosis of Lateral Columns, .......

Section of Spinal Cord in Lateral Sclerosis, . .

k a a a (( k u

Section of Medulla Oblongata,

Deformity in Amyotrophic Lateral Spinal Sclerosis,

Section through Medulla Oblongata in Amyotrophic

Lateral Spinal Sclerosis, ....

Writing of Patient with Locomotor Ataxia Dynamographic Tracing of Patient with Locomotor

Dynamographic Tracing of Patient with Locomotor

Superior Extremity of Healthy Humerus,

" " " Diseased Humerus of Patient

with Locomotor Ataxia, ....

Transverse Section of Spinal Cord, .

Longitudinal Section of Spinal Cord, Section of Stinal Cord in Locomotor Ataxia, Sclerosis of Columns of Goll,

Tumor of the Spinal Cord, ....

c< u a u u

a u a a «

Cortical Substance of Brain in Hydrophobia, Nuclei of Pneumogastric and Hypoglossal Nerves in

Hydrophobia, .....

Boot of Pneumogastric Nerve in Hydrophobia, Neuroglia-Cells of Cord in Hydrophobia,

Lande,

Hammond, .

PAGE

563 563

, 567

. 567

. 591 591

. 591 591

, 594

599 . 608

609 . 621 a

Lockhart Clarke,

. 625 u u

Pierrot,

. 632

. 637 u a

. 637

M

. 656

Leydcn,

Hammond, .

. 678 ct

. 680

LIST OF ILLUSTRATIONS.

Contractions in Hysteria,

U (( u

110. 111.

Catalepsy (after Photograph from Dr. Early), .

U U U U U u

Induced Catalepsy, ....

Ecstasy, .....

Hystero-Epilepsy, ....

Writing of Patient with Multiple Cerebro-Spinal Sclerosis, .....

Writing of Patient with Anapeiratic Paralysis, .

Exophthalmic Goitre (after Photograph from Dr. J. B. Crawford), .....

Diagram showing the Anatomical Divisions of the Spinal Cord, ......

PAGE

. 757 u

Hammond, .

. 770 u

. 774

Bourneville,

Hammond, .

. 787 u

. 790 a

Bourneville,

. 792

Hammond, .

. 802

. 663

DISEASES OF THE NERVOUS SYSTEM.

IITEODUCTION.

THE INSTRUMENTS AND APPARATUS EMPLOYED IN TEE DIAGNOSIS AND TREATMENT OF DISEASES OF THE NERVOUS SYSTEM.

Diseases of the nervous system, like those of the heart, lungs, and larynx, require special means of investigation and treatment. In no department of medical science has progress been more decided during the last decade than in that class of affections considered in this treatise, and undoubtedly a great deal of the advancement is due to the instruments and apparatus by which scientific research in this direction has become practicable.

In the present chapter I propose to describe the instruments and apparatus employed in the diagnosis and treatment of diseases of the nervous system, and to explain the methods by which they are used.

THE OPHTHALMOSCOPE.

The ophthalmoscope consists essentially of a concave mirror perforated in the centre, and of a double-convex lens. Several modifications of this arrangement are in use, but the simplest instrument is, in my opinion, the best for ordinary use, and this is Liebreich's, though, when very great exactness is required, as, for instance, in determining the depth of an atrophic excavation of the optic disk, Dr. Loring's ophthalmoscope is far preferable to any other.

Liebreich's ophthalmoscope consists of a polished steel mirror about one and three-quarters inch in diameter, concave, and perforated in the centre by a hole about the one-twelfth of an inch in diameter. The edges of this aperture are beveled, so as to afford as little obstacle as possible to the passage of the rays of light to the eye of the observer.

The mirror is set into a bronze ring with a handle, and there is attached also to this ring a clip for holding a concave ocular lens, 2 which in some conditions of refraction, either in the eye of the patient or that of the observer, is necessary in order to produce the requisite divergence of the parallel rays emanating from the patient's eye, and thus render the image of the fundus distinct. A direct image is thus obtained. The lamp, which should furnish a steady flame, is placed on the side of the patient's head corresponding to the eye to be examined, and the eye of the observer very close to that of the patient. This process gives a very satisfactory view of the fundus with the optic disk and retinal vessels, but requires care, and is more difficult than that by which the inverted image is obtained.

In this case the observer illuminates the fundus with the ophthalmoscopic mirror, and then interposes between the mirror and the eye a double-convex lens which he holds lightly between the thumb and finger, resting the ring-finger on the forehead of the patient, so as to make the hand steady, the little finger being disengaged so as to be employed in raising the eyelid if necessary.

The object-lens should have a focal distance of about two inches, and it should be held so as to bring the focus on the pupil. The lamp is placed behind and a little to one side of the eye to be examined. In order to see the optic disk, the patient is told to look at the ear of the observer on the side opposite to the eye being examined. In this way the axis of vision is directed inward, and the optic disk readily brought into view.

These examinations are made in a room lighted only by the lamp used in the processes. It is sometimes necessary to dilate the pupil with atropia, in order to obtain a view of the disk, but experience and tact will generally enable the observer to dispense with this rather disagreeable procedure.

Ophthalmoscopic examinations require the observer to possess a very thorough acquaintance with the anatomy of the eye, and also with the science of optics. Unless these qualifications are enjoyed, it will be much better to send the patient to a competent ophthalmic surgeon for an examination than to rush to hasty conclusions based on the most thorough ignorance. The real value of ophthalmoscopy in diseases of the nervous system is in danger of being disregarded through the sciolism of pert pretenders, who read papers and write memoirs without ever having seen the optic disk to recognize it.

Bouchut * gives the following list of abnormal conditions which are of importance in the diagnosis of diseases of the nervous system :

Papillary congestion ; peri-papillary congestion ; papillary anaemia, partial or general ; phlebo-retinal flexuosities ; venous pulsation in the retinal veins ; dilatations of the retinal veins ; retinal varices ; phlebo-retinal haemostases ; phlebo-retinal thromboses ; phlebo-retinal aneu-

1 " Du diagnostic des maladies du systeme nerveux, par 1' ophthalmoscopic," Paris. 1866, p. 15.

rism ; haemorrhages into the retina and choroid. The diseases in which he thinks ophthalmoscopy is valuable as a diagnostic means are — the several varieties of cerebral meningitis ; cerebral haemorrhage ; chronic encephalitis ; cerebral softening ; meningeal haemorrhage ; chronic hydrocephalus ; tumors of the brain ; contusion, commotion, and compression of the brain ; general paralysis ; atrophy of the brain ; chronic myelitis ; locomotor ataxia ; tetanus ; epilepsy ; essential convulsions ; insanity, and several others of less importance.

To these may be added cerebral congestion, general and partial ; cerebral anaemia ; and the various forms of sclerosis affecting the brain and spinal cord.

CEPHALOHuEMOMETER.

Although this instrument is intended for experiments on the lower animals, it enables us to arrive at very definite conclusions relative to the condition of the cerebral circulation. I first described it in a paper read before the New York Medical Journal Association in 1868, and shortly afterward published in the New York Medical Gazette. 1 It was devised in somewhat different form, independently of each other, by Dr. S. Weir Mitchell and myself, his being made first in point of time. The instrument consists of a brass, or iron, tube nickel-plated, which is received into a round hole made in the skull with a trephine. Both ends of this tube are open, but into the upper end is secured another brass or iron tube, the lower opening of which is closed by a piece of very thin sheet India-rubber, and the upper opening by a brass cap, into which is fastened a glass tube. This inner arrangement contains colored water. To this glass tube a scale is affixed.

This second tube is screwed into the first till the thin India-rubber presses upon the dura mater, and the level of the colored water stands at 0, which is in the middle of the scale. Now, when the quantity of blood in the brain is increased, the liquid rises in the tube, being' pressed upward by the elevation of the thin rubber closing the lower opening ; when the quantity of blood is lessened, the liquid falls by its own gravity.

The various parts of this instrument, as made by Mr. Ford, of this city, are shown in Fig. 1 {a i the first tube, which is to be screwed into the opening in the skull ; b, the second tube, closed at the lower end with thin sheet-rubber and containing the colored water ; c, the cap to which is cemented the glass tube ; d, the wrench for securing the first tube into the opening in the skull ; e, the instrument with all its parts in their places).

It was by this instrument that I was enabled to demonstrate, in the most conclusive manner, that during sleep the amount of blood circulating in the cerebral vessels is much less than during wakefulness, to

1 Also Journal of Psyclwlojical Medicine, January, 1869, p. 47.

DISEASES OF THE NERVOUS SYSTEM.

show the effect of bromide of potassium in lessening the amount of blood in the brain, of the sulphate of quinine in increasing it, etc, 1

Fig. 1.

^STHESIOMETEE.

The festhesiometer is an instrument for the purpose of determining the degree of tactile sensibility possessed by the patient. It was de-

Sleep and its Derangements," Philadelphi

Introduction

vised in 1858 by Dr. Sieveking, 1 of London. Its value in cases of aberrations of sensibility depends upon the fact, ascertained by Dr. E. H. Weber, that the capability of distinguishing two impressions, made upon the skin simultaneously, varies in different regions of the body according to the distance they are apart. In sensitive regions, as the end of the finger, the two points of a pair of dividers can be distinguished at about the twelfth of an inch apart, while in the middle of the back only one point is felt, though they are two inches apart. In accordance with this principle, the sesthesiometer is used to determine the sensibility of the skin in various diseases, it being well known that this is subject to variation.

Thus, when the sensibility is intact, two points, touching the back of the hand at the same time, can be distinguished as two points when separated an inch. If, in examining a patient, we should find that, when the two points were two inches apart, the patient felt but a single impression, we should know that he had lost sensibility in the cutaneous nerves of that part of the body.

Dr. Sieveking's aesthesiometer is nothing more than a beam-compass. It consists of a rod of bell-metal four inches in length, graduated

Fig. 2.

into inches and tenths of an inch. At one end is a fixed steel point ; another steel point is made to slide upon the beam, and can be fixed at

: British and Foreign Medico- Chirurglcal Review, January, 1858, p. 281.

any distance from the first by a screw which works at the top of the slide.

In 1861 ' I described an sesthesicmeter which I believe was the first used in this country. It consisted of a pair of dividers, to one arm of which the arc of a circle, in brass, was affixed. This arc was divided so as to measure tenths of an inch. A short time since, I suggested to Mr. Stohlman, the instrument-maker, a modification of this instrument, which for convenience is, I think, superior to all others. This, as closed, for the pocket-case, and open, as in use, is seen in the accomnying woodcut (Fig. 2), 2 and need not be further described.

The minimum normal distances at which the two points of the sesthesiometer can be distinguished in different regions of the body are stated in the following table : 3

Point of the tongue ■£ a line.

Palmar surface of the third finger 1 "

Red surface of the lips 2 lines.

Palmar surface of second finger 2 "

Dorsal surface of third finger 3 "

Tip of the nose 3 *

The palm over the heads of the metacarpal bones 3 "

Dorsum of tongue, one inch from the tip 4 "

Part of the lips covered by the skin 4 "

Border of the tongue, an inch from the tip 4 , "

Metacarpal bone of the thumb 4 "

Extremity of the great-toe , ... 5 "

Dorsal surface of the second finger. 5 "

Palm of the hand 5 "

Skin of the cheek 5 "

External surface of the eyelids 5 "

Mucous membrane of the hard palate 6 "

Skin over the anterior surface of the zygoma 7 "

Plantar surface of the metatarsal surface of great-toe 7 "

Dorsal surface of the first finger 7 "

On the dorsum of the hand over the heads of the metacarpal

bones 8 "

Mucous membrane of the gums , 9 "

Skin over the posterior part of the zygoma 10 "

Lower part of the forehead 10 "

Lower part of the occiput „ . 12 "

Back of the hand 14 "

Neck under the lower jaw 15 "

Vertex 15 "

1 "A Clinical Lecture on Chronic Myelitis," delivered in the Baltimore Infirmary, March 16, 1861, American Medical Times, June 15, 1861, p. 379.

8 First described by me in the Journal of Psychological Medicine, October, 1868, p. 830.

3 This table is quoted from Miiller's 'Physiology," translated by Baly, London, 1840, p. 752.

Skin over the patella 16 lines.

" " sacrum 18 "

" " acromion 18 "

The leg, near the knee and foot 18 "

Dorsum of the foot, near the toes 18 "

The skin over the sternum 20 "

" " five upper vertebras 24 "

" " spine near the occiput 24 "

" in the lumbar region 24 "

11 " middle of the neck 30 "

M over the middle of the back 30 "

The middle of the arm 30 "

THERMOMETER.

The thermometer is of use for the purpose of determining variations of temperature in different parts of the body. It should be graduated in tenths of a degree, and be held upon the part subjected to examination, so long as the mercury continues to rise or fall. Comparative determinations must be made under precisely similar conditions.

By means of these little instruments very slight variations of temperature can be ascertained. They consist of an extremely thin plate of copper about the size of a half-dime, soldered to a thin rod of bismuth. This latter is contained in a small tube of hard rubber furnished with a handle. The disks are two in number, and by means of delicate silk-covered wires are in communication with the poles of a galvanometer. If a lower extremity, for instance, is subjected to examination, one of the disks is placed upon it and the other upon the corresponding part of the other limb. If the temperature of both limbs be the same, the needle of the galvanometer remains quiet ; if either be warmer than the other, the needle is deflected to the north or south according as one or the other limb has the higher temperature. By this apparatus very much less than the hundredth of a degree of temperature can be determined with absolute accuracy. 1

dr. Lombard's thermo-electric deferential calorimeter.

For determining differences of temperature nothing equals this instrument, both for exactness of results and facility of application.

It consists, as shown in the accompanying cuts (Figs. 3 and 4), of

1 See my " Memoir on the Pathology and Treatment of Organic Infantile Paralysis," in Journal of Psychological Medicine, No. 1, July, 1867, p. 53.

24:

DISEASES OF THE NERVOUS SYSTEM.

a galvanometer (Fig. 3) and two thermo-electric piles (Fig. 4). The needle of the galvanometer is astatic, and is suspended by a delicate silk

Fig. 3 fibre so as just to swing clear of the scale it is to traverse. Above the needle and outside of the glass shade is a magnet by means of which the needle is readily made to point to the zero of the scale.

Upon the ebonite plate to the left of the galvanometer needle

INTRODUCTION.

Fig. 4.

are the bobbins and four little cups of mercury by means of which the connections are made, and the resistance of the thermo-electric current increased or diminished, according as it is necessary to make the needle more or less delicate in its indications.

There are two thermo-electric piles ; one of which is represented in Fig. 4, and which, for convenience of manipulation are furnished with handles. These piles are connected by their positive and negative poles, and the other positive and negative poles are connected with the stanchions seen on the ebonite plate of the galvanometer.

Having lowered the little metallic fork at the farther extremity of the bar over the ebonite plate, into the cup of mercury immediately under it, the apparatus is ready for use. The delicacy is increased by lowering one or two, or all three of the others, each one being in connection with the bobbin immediately opposite to it, and which, when the fork is out of the mercury, is included in the circuit, and hence has the effect of increasing the resistance. In the figure all the forks are represented as down.

To make an observation the thermo-electric piles are placed one on the part the relative temperature of which it is desired to know, and the other on the corresponding sound part. If the pile in connection with the stanchion nearer the corner of the ebonite plate is in contact with the hotter part, the needle will be deflected to the north. If the other be the hotter, the needle will be deflected to the south. The extent of the deflection indicates the relative difference in hundredths of a degree centigrade. It is to be remembered that the instrument must be placed on a firm table or stand, and must be so arranged that the end of the scale to the right of the cut points to the north ; the ebonite plate will therefore be at the south end, and the galvanometer needle points to the east. 1

With this apparatus of Dr. Lombard's it is easy to make relative determinations of temperature in a minute or two, and with great exactness and delicacy.

THE DYXAMOHETEK.

Several forms of an instrument for measuring the strength of patients have been devised. The best and most generally applicable is that of M. Burq, modified by M. Mathieu, an instrument-maker of

1 For a fuller description of this instrument and directions for its use, the reader is referred to the British Medical Journal for 1875.