Clinical electro-therapeutics, medical and surgical

Front matter

i LIBMYO^CONGRESS. *

*UNITElTsTATES OF AMERICA.*

CLINICAL

Preface

The need of a simple guide for the general practitioner has prompted the production of the following pages. I have endeavored to make them as practical as possible by avoiding as many of the confusing theories, technical terms, and unproved statements, as I was able. In presenting this little book to the profession, I intend to indorse electricity only as a very valuable remedy in certain diseases, not as a specific for every human ill, mental and physical. As a therapeutical means in nearly all forms of Nervous disease, Electricity is invaluable.

I have not mentioned several new modes of application, only because I think they have not been sufficiently or generally tested. My book is the compilation of well-tried measures and reported cases.

I do not enter into the detailed description of the various diseases I allude to, as there are many elaborate and concise works upon this subject, that may be consulted by the reader.

I am indebted to Drs. Frankel, Pifiard, Murray, Fisher, Eankin, and others, for their kindness in furnishing me with reports of cases and other data.

ALLAN McLANE HAMILTON. 110 East Thirtieth Street, April 10, 1873.

Contents

ELECTRO-PHYSIGS.

Chapter I. General Consideration Of Electric Phenomena

History of Electricity. — Frictional Electricity. — Conductors and Non-conductors. — Static and Current Electricity. — Electro-negative and Electro-positive. — Intensity and Quantity. — Ohm's Law. — Galvanometer. — Batteries, simple and compound. — Yoltaic Pile. — Smee's, Grove's, Grenet's, and Bunsen's Batteries. — Hammond's Battery. — Foreign Batteries. — Stohrer's Batteries. — Galvano-Faradic Company and Curt W. Meyer's Batteries. — Brenner Batteries. — Pulvermacher's Chains. — Garret's Disks, etc. — Rheotome, Rheostat, Current-Selector, etc., Page 11

Chapter II. The Induced Current

General Laws of the Induced Current. — Theory of Induction. — Rotary and Chemico-Magnetic Batteries. — Induction Apparatus. — Galvano-Faradic Company's Apparatus. — Curt W. Meyer's Apparatus, . . . . . .26

ELECTRO-PHYSIOLOGY.

Chapter III. Phenomena Of The Two Currents

Inherent Electricity of Animal Bodies. — Phenomenon in Nerve-Trunks and Muscles. — Action of Blood upon the Galvanic Needles. — Scoutellen's Theory. — Effects of Electricity upon special parts. — Different effects of the Two Currents. — Different conditions varying the influence. — Action on the Nervous System. — The Brain, Spinal Cord, etc. — Tongue, Eye, Ear, etc. — Motor Nerves and Muscles. — Electrotonus. — Point of Indifference, etc. — Muscular Contractility and Sensibility. — Upon the Sensor Nerves. — Upon the Sympathetic. — Upon the Blood. — Upon the Organs of Digestion and Secretion. — Upon the Urinary and Sexual Organs. — Upon the Absorbents. — Influence upon the Process of Nutrition. — Upon the Skin, 32

8 CONTENTS.

ELECTRO-THERAPEUTICS.

CHAPTEE IV.

Nomenclature. — Difference between the Two Currents. — Their Characteristics. — Electrodes. — Sponge Electrodes. — Duchenne's Electrodes. — Metallic Electrodes. — Points de Duchenne. — Duchenne's Cup. — The Electric Scourge or Brousse. — Double Electrodes, Rheostat, .... , Page 43

CHAPTER Y.

GALVANIZATION.

Effects of Galvanization of the Brain. — Of the Cord. — Galvanization of the Great Sympathetic (Central Galvanization). — Diplegic Contractions. — Galvanization of the Pneumogastric. — Of the Ear, Tongue, Eye, etc. — Galvanization of the Rectum. — Of the Urethra. — Galvanization of the Nerves and Muscles, . 49

CHAPTER VI.

FAEADIZATION.

Duchenne's Observations, — Methods of Faradization. — Faradization of the Nerves and Muscles. — Electro-Anatomy. — Faradization of the Skin. — Of the Tongue, Ear, Eye, etc., etc. — Of the Rectum, Bladder, Larynx, and Pharynx. — Of the Uterus, etc., etc, . . 57

CHAPTER VII.

DIAGNOSIS BY ELECTEIOITY.

Diagnosis by Electricity, etc., . . . . . . . . . .65

SPECIAL ELECTRO-THERAPEUTICS.

CHAPTER VIII.

PAEALYSIS.

The Use of the Currents. — Modification of the Currents in Special Paralyses, etc. — Cerebral Paralysis. — Diagnosis of Cerebral Paralysis. — Seguin's Thermometer. — JEsthesiometers. — Dynamometer. — Treatment. — Prognosis. — Spinal Paralysis. — Peripheral Paralysis. — Lead-Paralysis. — Hysterical Paralysis. — Infantile Paralysis. — Traumatic Paralysis. — Facial Paralysis. — Reflex Paralysis. — Paralysis of the Bladder. — Rheumatic' Paralysis. — Dysphonia and Aphonia. — Glossolabio-pharyngeal Paralysis. — Progressive Locomotor Ataxy. — Progressive Muscular Atrophy, etc., etc., : *70

CONTENTS. 9

CHAPTER IX.

H YPEK^ESTHESI A, ETC

Neuralgia. — Its varieties. — Etiology. — Facial Neuralgia. — Cervico-brachial Neuralgia. — Intercostal Neuralgia. — Gastrodynia. — Tic-Musculaire. — Sciatica. — Rheumatism. — Anesthesia. — AnEesthesia of the Sensory Organs. — Asphyxia, etc., Page 102

CHAPTER X.

CONVULSIVE DISEASES.

Chorea. — Scrivener's Palsy. — Paralysis Agitans. — Epilepsy. — Tetanus. — Asthma. — Torticollis. — Diseases of Women. — Intra-Uterine Galvanic Pessary, etc. — Electricity in Obstetrics. — Diseases of the Eye. — Constipation and Intestinal Obstruction. — Skin-Diseases, 115

CHAPTER XL

ELECTEOLTSIS.

Theory of Electrolysis. — Anions and Cations, etc. — Steps of Operation. — Needles

and Apparatus. — Electrolysis of Aneurisms (Galvano-puncture). — Malignant,

Erectile, and Serous Tumors. — Goitre. — Hydatids. — Hydrocele. — Stricture. —

• Galvano-therapy of Wounds and Ulcers, Naevi, etc., .... 133

CHAPTER XII.

GALTANO-OAUSTT, ETC.

Batteries, Electrodes, etc. — The Operation. — Cases. — Miscellaneous Uses of Electricity. — Electric Baths. — Absorption of Inflammatory Products. — Spermatorrhoea. — Orthopraxy. — Vomiting of Pregnancy. — Detection of Metallic Substances. — Carbuncles and Furuncles, etc., etc., 159

Appendix

Management of Batteries. — Solutions for Batteries. — Insulation of Needles. — Galvauo-Causty Apparatus, etc., etc., 182

ELEOTBO -PHYSIOS.

CHAPTEK I.

GENERAL CONSIDERATION OF ELECTRIC PHENOMENA.

History of Electricity. — Frictional Electricity. — Conductors and Non-conductors. — Static and Current Electricity. — Electro-negative and Electro-positive. — Intensity and Quantity. — Ohm's Law. — Galvanometer. — Batteries, simple and compound. — Voltaic Pile. — Smee's, Grove's, Grenet's, and Bunsen's Batteries. — Hammond's Battery. — Foreign Batteries. — Stohrer's Batteries. — Galvano-Faradic Company and Curt W. Meyer's Batteries. — Brenner Batteries. — Pulvermacher's Chains. — Garret's Disks, etc. — Rheotome, Rheostat, Current-Selector, etc.

It is unnecessary to follow up the history of electricity ; suffice it to say that Thales, many centuries ago, demonstrated the first rudiments of this force, and, since his day, Galvani, Yolta, Ampere, Franklin, Faraday, and many others, have groped in the darkness and uncertainty of the subject, and have successively brought new facts to light to astonish the world and advance the knowledge of electric science.

Thales, who lived six centuries before Christ, knew that, when amber was rubbed with silk, it acquired the property of attracting light bodies, but not till several hundred years afterward was it known that other substances possessed a like quality ; and these were sulphur, wax, glass, etc. Dr. Gilbert, physician to Queen Elizabeth, was the demonstrator of these facts. In the year 1789 contact electricity was discovered by Galvani, and in the year 1831 induction electricity was given to the world by Faraday.

When a glass rod or stick of sealing-wax is rubbed with a piece of flannel or fur, it will be found to have acquired the power to attract some very light body — for instance, a pith-ball,

CLINICAL ELECTRO-THERAPEUTICS.

feather, gold-leaf, or piece of paper — which is repelled afterward. All substances do not, however, receive this electric excitement ; some metals being occasional exceptions. When a body, electrified, is brought in contact with a new substance, that substance will or will not receive the electricity from the first substance — for instance, when one part of a glass rod is electrified by friction, the extremity of the rod not acted upon will not receive the electricity from the excited part immediately in contact. This property of receiving and conveying electricity we call conduction. Bodies are conductors, or, vice versa, non-conductors. But this division is not definite ; some bodies will only offer resistance to the passage of the current, and conduct poorly. We call this latter class 1 semiconductors.

Connectors.

Metals.

Well-burnt charcoal.

Graphite.

Acids.

Aqueous solutions.

Water.

Snow.

Vegetables.

Animals.

Soluble salts, etc.

Semi-con ductors.

Alcohol and ether.

Powdered glass.

Flowers of sulphur.

Dry wood.

Paper.

Ice at 0°.

Non-conductors.

Dry oxides.

Ice at 25° C.

Lime.

Lycopodium.

Caoutchouc.

Air and dry gases.

Dry paper Silk.

Class.

Wax.

Sulphur.

Resins.

Amber.

Shellac.

This list is arranged in the order of decreasing conductivity, or increasing resistance. Certain influences affect conductivity, i. e., heat, cold, and moisture; red-hot glass is a very good conductor, water when frozen is a bad one, etc. Poor conductors are sometimes called insulators, that is, they confine electricity to good conductors which they surround.

It is impossible, without going into the subject very deeply, to give a minute description of the phenomena of electricity ; for this I refer you to any of the good text-books.

In Electro-therapeutics we make use of two varieties of electricity :

1 Ganot's " Physics," p. 565.

1. Static or frictional electricity.

2. Current electricity.

This latter includes galvanism, and induced, or faradic electricity.

Static electricity is generated by friction, and, whether produced by the cumbrous plate-machine of Holtz, or the simple glass tube and handkerchief, is the same. It has a certain peculiar characteristic, and that is, that it has the power of producing a change in the air, converting the oxygen immediately into ozone. Static electricity is analogous to lightning in this respect, and the peculiar change in the atmosphere after a thunder-storm is due to the production of ozone on a larger scale. Static electricity produces but feeble physiological changes. It is only when its tension is very great that any violent effects are shown, and then it may produce even death by the violence of its shock. It has little value in the field of electro-therapeutics. Golding Bird has used it in chorea with success, and others have pronounced it efficacious in amenorrhcea and other female diseases.

When applied to the skin, it produces a peculiar prickling sensation, accompanied by slight redness of the cuticle, and by hyperesthesia. It does not penetrate beyond the superficial muscles, and even the contractions it produces in them are very weak.

The effects of static electricity may be condensed, however, by collecting it in a Leyden jar. The sensation communicated to a nerve or muscle is intense. A numbness in one end, and a violent contraction in the other, are experienced. Small animals are easily killed by a moderate charge. The Leyden jar is clearly indicated when an irritant is wanted for the superficial tissues ; it is not safe to use it, however, when deeper action is desired. 1

CURRENT ELECTRICITY.

This form of electricity is also known as dynamic, or contact, and is by far the most important variety.

If two unlike conductors are brought together, either solids and fluids, or metals and gases or fluids, an electric current will

1 Meyer's " Medical Electricity."

be generated. The current produced by gases is very weak, but when two metals, an electro-negative and electro-positive, are brought together in an exciting solution, the current is more powerful. The more remote from each other the bodies stand in the scale, the more active will be the production of the electric fluid. The following table gives the electro-negative and electro-positive elements in their proper order :

+ 1

Zinc.

Iron.

Platinum.

Lead.

Antimony.

Carbon.

Tin.

Copper.

Silver.

Gold.

When two of these are placed in contact in acidulated water, the current in the connecting wire proceeds from the one lower in the scale to the one higher, the two extremes giving the most intense results.

The electrical deportment of any metal depends, therefore, on the metal it is associated with. Iron, for instance, is electro-negative toward zinc ; copper is electro-negative toward zinc ; and iron but electro-positive toward silver.

If the wires connecting the plates of the battery be cut, the terminal ends of each receive the name of poles.* The current passes from the — to the -t- under the surface of the solution, and vice versa above. When the extremities of the wire are brought together, the point is called the terminal arch.

Polarization. — During the action of all batteries there is a process going on known as polarization, which presents the following phenomena : When the elements of the battery are immersed in the exciting solution, hydrogen and oxygen are formed by the decomposition of the water. The hydrogen goes to the copper pole at once, and the oxygen to the zinc. There is a local action going on all the time on the surface of the plates ; by this small currents are generated between the impurities in the zinc and the zinc itself. As this process continues, the current loses its intensity, and is finally destroyed.

1 + represents the electro-negative sign. 8 — represents the electro-positive sign. 3 " Electrode " is also used for the term pole, from qXetcrpov and oSog, way,

Amalgamation of the zinc-element prevents this. Another phenomenon of polarization may be the accumulation of hydrogen at the negative plate, and with this there will be a deposit of zinc, or positive metal, on the copper, or negative plate. In this way a current directly adverse to the original will be produced. This tendency may be overcome by simply breaking the current or wiping the plate.

Quantity antd Ixtexsity are terms of great importance in the nomenclature of the electric current. Quantity signifies an inert volume of electricity ; while tension, or intensity, the energy by which the cm-rent is impelled. The origin of this propulsion is due to the number of cups and the strength of the exciting solution. For quantity a large plate-surface is required, while for intensity a great number of small cells generate a current of tension with no more quantity than the first cell furnishes. The tension increases with the number of plates ; in the middle the free electricity is inconsiderable, while the poles of the battery are the two opposing halves. The junction of the negative element of one cell to the positive of the other prevents the formation of more than a certain amount of electricity, and the resistance it has the power to overcome in its circuit, in many cells, is just the power in one cell multiplied by the number.

Ohm's law is unintelligible to the ordinary mind almost, on account of its obscurity ; but Smee, in his " Elements of Electro-Metallurgy," * has condensed it as follows :

" The action (A) is equal to the electro-motive force (E) multiplied by the number of cells (n), divided by the resistance the current has to overcome, external to the liquid of each battery (K), plus the resistance encountered by the peculiar arrangement of each cell (r) multiplied by the number of cells (n).

It would be thus :

nE A ~nK + r

In this formula, Ohm has discarded the terms quantity and intensity, and unfortunately has adopted the contact instead of the chemical theory of the pile."

1 " Elements of Electro-Metallurgy," p. 11.

CLINICAL ELECTRO-THERAPEUTICS.

All the phenomena of tension may be studied with the galvanometer, and this consists of a needle balanced above a coil of insulated wire ; when this is connected with the battery, the deflection of the needle indicates the tension of the current.

Galvanic batteries may be simple or compound. This dis-

Fig. 1.— Simple Battery.

Fig. 2.— Compound Battery.

tinction consists in the fact that a simple battery has one cell (Fig. 1), while a compound battery has a number, the poles of the elements in each being joined alternately (Fig. 2), as I mentioned when I spoke of tension. When the terminal ends of the wires connecting the poles are separated, the circuit is said to be broken. The combination of the various electro-negative and electro-positive metals and the variety of exciting solutions are almost numberless. From the simple voltaic pile, with which most of the earliest experiments were made, to the more complicated apparatus of the present day, the march of improvement has been rapid. The voltaic pile is dismissed almost entirely. Dr. Hammond, of this city, has made an improvement, however, and presents to the profession a most complete and excellent instrument (Fig. 3). It consists of a number of perforated boxes of zinc and copper, between each of which is interposed a piece of felt or cloth moistened by an exciting solution. In Europe the voltaic pile is confined chiefly to the operation of electrolysis by Ciniselli and others.

Undoubtedly the simplest form of cell is that of Smee. (Fig. 4.)

Smee's lattery is formed of carbon or silver and unpolished zinc well amalgamated, and needs but one cell and one fluid to excite it. The silver plate is coated with platinum. The zinc

Fig. 3.— Dr. Hammond's Voltaic Pile.

and the silver plates are held together by clamps, and the interposition of a bar of hard wood prevents the passages of the current from plate to plate. The exciting solution is water acidulated with one-seventh its bulk of oil of vitriol.

Grove's lattery is most powerful ; but, as its action is attended with the fumes of hyponitrous acid, it does not rank as high in the list of electro-therapeutical instruments as some others. The negative element is platinum, and the positive zinc. The platinum plate is enclosed in a porous cell filled with nitric 2

CLINICAL ELECTRO-THERAPEUTICS.

acid; the zinc surrounds it, immersed in a dilute solution of sulphuric acid. In the operations of galvanic surgery perhaps it has value.

Bunsen's "battery is a slight modification of Grove's. In this the platinum plate is substituted by carbon, and a solution of bichromate of potash is used instead of nitric acid.

Grenefs lattery, described in many foreign text-books, is constructed for the purpose of galvano-causty. The elements and solutions are the same as in the Bunsen. Curt W. Meyer, of this city, has recently invented an improvement on the Smee battery, which is superior to the original (Fig. 5). Platinized lead and a large element of zinc are used, the exciting solution being the same.

Hammond' 's Battery, 1 — Quite recently Dr. Hammond made a modification of Hill's cell. Each cell contains about half a gallon of fluid. A disk of sheet-copper is laid on the bottom of the cell ; an insulated wire connects with this, forming the positive pole, the copper being the negative plate. About six inches above this a zinc plate is suspended upon a hanger from the edge of the glass. This zinc has a large hole in the centre. A binding screw on the hanger forms the negative pole. The body of the fluid consists of a saturated solution of sulphate of zinc. Occasionally crystals of sulphate of copper are dropped through the aperture in the zinc to the bottom of the fluid. We

1 New York Medical Journal, November, 1871, p. 486.

thus have two distinct solutions, which are separate, the denser solution of sulphate of copper remaining below. The two

Fig. 5.

plates are constantly surrounded by different solutions. A sixty-cell battery of this kind has been in use at the New York

Fig. 6.— Hammond's Permanent Battery.

State Hospital for the Diseases of the Nervous System for nearly a year, and, beyond the occasional supply of a few crys-

CLINICAL ELECTRO-THERAPEUTICS.

tals of sulphate of copper, no other trouble has been taken, and its action is now as intense as on the first day of erection.

A film of paraffin e poured on the surface of the fluid in each cell prevents evaporation, and does not interfere with chemical action. The Galvano-Faradic Company manufacture this battery, and also a " regulator," combining current-selector, polarity-changers, rheotomes, and a galvanometer, upon the plan of Remak's instrument.

There are many foreign batteries which are no better than those made in this country. These are Middledorp's, Remak's, Fromhold's, and others. Drs. Piffard and Sass, of this city, both use Smee's elements, which they find answer every purpose as well as those of European manufacture. The desideratum in galvanic batteries is —

1. That chemical action and consequent waste of material should be slight. This is overcome by using certain weak solutions, and having an apparatus that can easily be made to remove the elements from the solution after use.

2. The batteries must neither have too great quantity nor too little tension.

The Stohrer battery combines these requirements, and has

Fig. 7.

been made by different makers in this city, with improvements. Messrs. Tiemann and Drescher both make the Stohrer batterv,

GENERAL CONSIDERATION OF ELECTRIC PHENOMENA.

and the Galvano-Faradic Company have constructed many which are the best I have seen. I have one in my office which I cannot too highly recommend.

The elements in the Stohrer battery are carbon and zinc ; these are arranged side by side in a glass vessel, with a solution of bichromate of potass, sulphuric acid, and water, as an exciting medium. (See Appendix.) From sixteen to thirty-two cells are placed in two parallel rows, two cells connecting on either side. Above and between the two rows runs a long, wooden track, and on this slides a " coupler," to which are affixed two binding posts, from which emerge the positive and negative wires. By sliding this coupler backward or forward, any number of cells can be used, and this is indicated by corresponding numbers engraved on a strip of brass that runs the entire length of the battery. Fig. 8 represents the apparatus made by the Galvano-Faradic Company. Two handles (2.2.) lower the cells, so that, when out of use, the solution is not in contact with the plates.

Curt W. Meyer has made a very beautiful instrument, which he calls the " Universal Platina Zinc Battery." As the name indicates, platina and zinc are the elements. The exciting solution is sulphuric acid (Fig. 9).

Yaried devices on top select the current, or number of cups, and also interrupt the current.

Numerous attachments are adjusted to these batteries. The battery of the Galvano-Faradic Company is supplied with a very ingenious current-changer, by which the polarity of the current can be instantly changed. We can get the descending or ascending currents in this manner.

To most of the batteries is attached an interrupter, or rheotome, by which shocks may be made by breaking the current. This is in some done by a toothed wheel, or in others by a pendulum moved by clock-work.

Mr. Curt W. Meyer has just perfected a battery which certainly deserves great praise for its simplicity. A glance at the cut (Fig. 10), and reference to Mr. Meyer's description, will enable the reader to appreciate its advantages. The elements are carbon and zinc :

" The construction of the single cell will be seen in A.

CLINICAL ELECTRO-THERAPEUTICS.

At the bottom of a glass tube, of the dimensions of a test-tube, is a platinum wire melted into it, extending as well inside as outside. The tube is filled one-third of its height with prepared gas-carbon ; above this carbon a saturated solution of water and sal ammonia is poured up to two-thirds the height of the tube, by which means the porous jar, as required in a Leclanche battery, becomes unnecessary. The upper part of the tube is coated on the inside to prevent the solution from adhering to the glass, and so as not to form crystals of sal ammonia, which,

CLINICAL ELECTRO-THERAPEUTICS.

by capillary attraction, would further soak up the solution and cause these crystals to rise over the upper edge of the tube. The tube is closed loosely on the top by means of a rubber stopper in which a rod is fastened connecting the zinc, so as not to be moved up or down.

" B. The current-selector (m) serves to connect any desired number of elements by means of the two cord-pins (a and h) ; but only one must remain connected at a time ; the second cord-pin only serves to act, when an alteration of the number of elements is required, in which case the connected pin remains connected until the desired new connection is completed by means of the disconnected cord. In this manner any desired connection or any alteration in the number of elements, as well as any desired current-fluctuations, can be produced without causing an entire interruption."

The Galvano-Faradic Company have recently made a most excellent modification of the celebrated Brenner battery, by which the cumbersome table of the original battery is done away with, and a neat glass case substituted. These batteries are furnished with a most complete set of rheostats, galvanometer, current-selector, etc., in a very small space.

Pulvermacher's chain consists of a number of alternate slips of copper and zinc wired together in the form of a chain. When these are immersed in dilute acetic acid, a mild current is generated. These chains have been worn about paralyzed limbs, and the action sometimes has been sufficient to vesicate the part. Numerous disks, " galvanic insoles," etc., have been lauded by different physicians. Garret's disks will be hereafter alluded to.

CHAPTEE II.

THE INDUCED CUREENT

General Laws of the Induced Current. — Theory of Induction. — Rotary and Chemico-Magnetic Batteries. — Induction Apparatus. — Galvano-Faradic Company's Apparatus. — Curt W. Meyer's Apparatus.

The second division of current electricity is the induced, or faradic current ; but, before we go further, it will be advisable to consider briefly the theory of induction.

It was Faraday who discovered that, at the moment of opening and closing a galvanic circuit, a current was produced in another conductor placed near that of the battery, and that this current ran in the opposite direction to the primary one. This current is but instantaneous, however, and only renewed on the closure or opening of the circuit, to disappear again on the instant, and reappear as often as the connection is made or broken, for, during this interval, or during all the time that the first current flows, the new one does not exist. A current of this kind is called the induced, or secondary current, in opposition to the inducing, or primary one. This current was called by Duchenne faradism, in honor of Faraday, its discoverer ; whence have come into use the terms faradic or faradaic, and faradization, a term suggested in analogy with galvanization.

In the production of the current by the magneto-electric machine, a bar of soft iron is magnetized and demagnetized, and this induces in a parallel wire a vibratory or to-and-fro current, which is more magnetic than the inducing current.

The currents produced by the rotatory machine are broken in the interval between the interruptions, and are barely appreciable on account of their brevity.

THE INDUCED CURRENT.

The course of the current is an important consideration, and may be learned by holding the conductors, or electrodes, in the hands, when the most pain will be experienced where the current leaves the body — that is, in the hand grasping the negative electrode.

The rotary magnetic machine and chemico-magnetic instrument both produce the same kind of electricity. They both have their champions, but the faradic current is that in general use. The electro-magnetic instrument often needs two persons for its manipulation, while the faradic can be set in motion and stopped without trouble, and the electrodes can be manipulated by one person. The electro-magnetic current is not reliable, varying in strength at different times. The coil of the induction apparatus must be small, and the wire thin and fine. As I have said before, the induction apparatus should have two currents — a primary and secondary. ■ Duchenne calls them " currents of the first and second order." The primary acts more particularly on the muscles, while the secondary influences the sentient nerves.

Induction Apparatus. — An induction instrument must consist of a battery, a coil, a centre bundle of wire, or piece of soft iron, and contrivances to break the current. The instruments in most common use are of this variety. Many different kinds are made, most of them wretched affairs, fabricated chiefly for empirics and domestic use. The more brass that attracts the eye, the better. One inventor states in his circular that his instrument furnishes ten currents ! It is better that Faraday died when he did, Fl& - n -

than to have lived to see his discovery so improved upon.

Happily we are emerging from this dark age, and the instruments now offered for sale are constructed upon scientific principles. Many makers now turn out really better instruments than those of European make. The instruments made by the Galvano-Faradic Company, of this city, Messrs. Curt Meyer and Drescher, of ]S"ew York, and Hall, of Boston, are all excellent. I have used the induction apparatus of the

CLINICAL ELECTRO-THERAPEUTICS.

first-named company for some time, and am convinced that there are none better made.

Fig. 11 represents a very ingenious attachment made to the Galvano-Faradic Company's batteries. It consists of a fork which regulates the vibrations of the rheotome by which the

±tz intervals may be almost imperceptible on account of their brevity, or, contrarywise, the shocks occur very slowly, the intervals being longer.

THE INDUCED CURRENT. 29

They are portable, efficient, and never get out of order. Probably every one is familiar with this apparatus. Fig. 12 gives a view of it, with the case removed.

I append the description which Mr. Bartlett has published :

" Letter A represents the graduated kinged rod, to the lower end of which the zinc plate is attached. The hinge (b) enables the rod to be laid on horizontally when the battery is not required for action, thereby preventing the accidental immersion of the zinc plate in the battery fluid. The graduated points on the rod exhibit the depth to which the zinc, when the rod is lowered down, becomes immersed in the fluid, thus indicating the battery-power obtained.

" The spring 1 presses against the head (c) of the rod when that is fully down in the cell, and thereby becomes impaired if it is not free from acids and untarnished.