Part 3

[8] _The Galvanometer as an aid to the Dosage of Electricity._--The dose of voltaic electricity is made up of two factors, (_a_) the strength of the current and (_b_), the time during which it is applied to the patient. [SN: The Galvanometer as an aid to the Dosage of Electricity.] The strength of the current is directly dependent upon the number of cells employed, but, unfortunately, cells of dissimilar construction evolve currents of very unequal strength; while cells that have been freshly charged are more powerful than similar ones that have been partly exhausted by use; and, therefore, to speak of a current from “so many cells,” though, practically, a convenient method of dosage, fails to convey any _exact_ idea of a measured and unvarying quantity. It is a comforting theory to electro-therapeutists that a galvanometer will enable them to administer their doses of electricity with as much exactitude as we daily prescribe so many grains, or so many minims of ordinary medicines; but, like some other theories which save us much trouble, when adopted as theories _only_, it fails us in practice (at least according to my experience), and chiefly so, because a galvanometer can be usefully employed only when it is included in the circuit of a continuous current, as, _e.g._, in aneurismal electro-puncture; and, I believe, I am within the mark in saying that electrizations, which even admit of its useful employment, are indicated in barely 5 per cent. of ordinary cases in electro-therapeutics; and that it is of no practical utility, where we most want aid, in measuring, not the current which leaves the battery terminals, but that which, after overcoming the very variable resistance of the human skin, really reaches the underlying muscular and nervous tissues, which, in 95 per cent. of our cases, we desire to influence, not by a constant, but by an interrupted Voltaic current; and the amount which really reaches these tissues depends largely upon the condition of the patient’s skin, and, I may also add, upon the kind and shape of the conductor, and its degree of moisture, &c.; and the operator will do well to graduate his dose of electricity by a consideration only of the three factors, number of cells, effect upon himself, and effect upon his patient, discarding entirely the use of any merely mechanical aids to graduation.

I am induced to speak thus strongly because men of scientific reputation have advocated the habitual use of the galvanometer, not alone by medical men trained to precision of observation, but by private patients as “_enabling them to carry on the treatment at home with all the accuracy desirable!_” The prospect of the ordinary patient provided with a battery, the use of which he is complicating by a galvanometer, is anything but reassuring to those physicians who not only prescribe electricity, but are themselves habituated in applying it--which, by the way, is a very different thing--and who have had frequent experience of the manner in which patients misunderstand, or fail in correctly carrying out, the most explicit directions. Electricity will be left in the hands of specialists, and necessarily do but a tithe of the good it is capable of affecting, until the mass of the profession can be induced to master the few preliminary details essential to its successful application, and I fear that the suggestions that have been made--suggestions which I believe to be entirely without foundation--that there exist practical difficulties to its dosage, will tend to postpone rather than to accelerate its more extended use.

Should any of you desire to use a galvanometer, that patented by Sprague, of Birmingham, is the one most adapted for use in medicine. Electricity is a force, and as with other forces it has its standard of measurement. In mechanics we know that the power sufficient to raise one pound to the height of one foot is the basis of measurement. Similarly in electricity the unit of measurement is the force which will raise one gramme to the height of one metre, and the standard multiple of this was called a “British Association Unit,” or shortly, a “B.A.” unit, and it is now called an “_Ohm_” when used to measure the resistance offered to the current, and a “_Veber_” when used to measure the strength of the current itself. The ordinary galvanometer is founded on the principle that a magnetic compass needle has a tendency to place itself at right angles to a current of electricity, and the degree to which the needle is deflected is a measure of the quantity of electricity, but the angle of deflection is not proportionate to the current strength, and it differs in different galvanometers; but in “Sprague’s Galvanometer” the dial is divided, not into degrees, but into divisions of thousandths of _Vebers_--divisions which were obtained by noting the deflections given by the needle with currents of known strength. I am indebted to Mr. Sprague for his courtesy in endeavouring to so modify his galvanometer as to render it available as a graduator of doses of interrupted Voltaic electricity, but although he has not succeeded in doing this, he has constructed for me an instrument which, supposing that a battery be partially exhausted, will indicate with precision the absolute strength of, say, twelve of its cells as compared with twelve newly-charged cells, and also the condition of each individual cell, points often of much practical convenience in an Hospital Electrical Room.

[9] A little care is needed to regulate the vibrating needle. The spring should but _barely touch_ the hammer, the adjustment being almost entirely regulated by the protrusion or retraction of the needle by the action of its screw; and the _slightest twist_ of this screw will be sufficient. When the vibration is uneven or stops, and careful manipulation of the needle fails to re-establish it, remove the needle and clean its point as directed in the text.

LECTURE II. METHODS OF APPLYING ELECTRICITY.

GENTLEMEN,

[SN: Résumé of First Lecture.]

In our first Lecture we studied the different kinds of electricity employed in medicine, and the construction and management of batteries. I reminded you that we made use of three kinds of electricity; firstly, of friction or static electricity, _Franklinism_; secondly, of the electricity of chemical action, _Voltaism_, or _Galvanism_; and, thirdly, of induced electricity, _Faradism_:--that there had been certain difficulties in the employment of Franklinism, but that these difficulties no longer existed; that Voltaic electricity was electricity in motion, or current electricity, but that while its current (unless artificially interrupted) was always _continuous_--flowing, that is, in an unbroken stream--and from the positive to the negative pole, until the battery was exhausted--it by no means followed that it was _constant_, that is, that it did not vary appreciably in power during application; that only batteries supplying a fairly constant current were fitted for medical use, and that all others should be rejected. We then considered different batteries, both fixed and portable; that while large fixed low tension batteries were unquestionably superior in their therapeutic effects, patients unfortunately were not always movable, and that a portable battery became, therefore, a _sine quâ non_; that portable batteries might be conveniently divided into two classes, one in which electricity was generated by the elements being immersed in an exciting fluid only during actual use, and being taken out of the fluid immediately after use; and the second that in which no removal of the elements was necessary; that the Voltaic current was graduated into doses by some arrangement determining the number of cells to be employed in each case, but that this method, while practically useful and sufficient, failed to convey an exact idea of a measured and unvarying quantity of electricity; and that it had been contended that by the use of a galvanometer, doses of electricity might be as accurately administered as so many grains or minims of ordinary medicines, but that, perfect as the theory might be, I had personally failed to obtain help in practice from a galvanometer; that next in importance to a method of dosage, was it to be able to instantly change the direction of the current, or to at once turn it “off” or “on,” in addition, of course, to the fundamental requisite of a continuous supply of electricity of sufficient quality and quantity.

We next considered the induced or _Faradaic_ current, so-called, which I reminded you is not a current at all, but a rapid discharge or succession of those momentary shocks, each perfectly distinct in itself, and separated by an appreciable interval of time from its fellows, which Faraday discovered to be generated or induced by a Voltaic current flowing along a wire in other wires parallel to, but separated from, the first wire; that by winding the two wires upon two movable reels and introducing one within the other, not only might these _secondary_ currents be multiplied indefinitely in proportion to the number of spirals of wire, but by introducing or withdrawing the one from within the other an exact method of graduation was afforded us. I pointed out to you that there was no therapeutic distinction between the so-called primary and secondary currents, and I recommended you therefore to use only the currents of the secondary coil. I then showed you the construction of Faradaic instruments, and of instruments combining both Voltaic and Faradaic currents, and our survey was completed by a consideration of the different varieties of conducting wires or cords, and my recommendation of thin gutta-percha covered copper wire as generally superior to any other form. We have to-day to study methods of applying electricity, and to learn how to use the instruments, with the construction and properties, of which I trust you are now familiar; and, Gentlemen, it is well worth your while to have obtained this knowledge, for its possession will not only enable you to readily rectify any faults in the working of your batteries, but the necessity of sending them to the instrument-maker may be often avoided.

We have already studied methods of applying Franklinism.[10]

Voltaization and Faradization may both be applied either generally--as in the different forms of electrical baths--or locally.

[SN: The Application of Electricity.]

A convenient method of applying electricity, when very strict localization is not required, is to insert the feet and hands of the patient, or one foot and one hand, as the case may be, in separate vessels containing tepid salt and water with which the conducting wires of the battery are in contact, the current being allowed to circulate during the time required. Ordinary foot-pails, basins, or jugs, will fulfil every requirement; while thick telegraph wire answers well to connect the battery with the vessels of water, as it is little liable to break and wears well. A variety of the constant current (originated by Dr. Radcliffe) is very readily applied in the way just described, with the addition only of some means of insulating the patient and the accessories, and of a length of ordinary uninsulated copper wire. [SN: Radcliffe’s Positive Charge.] Dr. Radcliffe believes that an administration of _positive_ Voltaic electricity, somewhat analogous to the charge of Franklinic electricity, is frequently beneficial. He insulates the patient and the accessories, and having connected the negative pole with the earth by a wire which he calls a “ground-wire,” he allows the current to pass. With careful insulation the negative electricity passes away by the wire, and while the current circulates the patient continues “charged” with positive electricity. There must be two wires from the negative pole, one to be applied, as well as the positive, to the patient, and the other taken “to earth.” This latter may be conveniently attached to a chandelier or gas-pipe, which always gives a direct metallic conduction to the ground. A perforated vulcanized indiarubber mat, or a sheet of gutta percha, or a glass-legged stool can be employed to insulate the patient and the accessories.

[SN: The Electric Bath.]

There is another generalized application which has been much advocated, and remarkable statements have been put forth, not only of its curative power in almost every disease, but also of its purely physical and chemical effects--I refer to that by “Electric Baths,” several establishments of which exist in London, but you need not send your patients to them. You can teach them how to take an electric bath in their own bed or bath-room. A bath sufficiently large for the patient to recline in it should be insulated by glass supports (four stout tumblers will do very well), and filled with water at a temperature of 95 to 100 degrees. A metallic plate in connection with one pole may be inserted at the head, and a second plate in connection with the other pole at the foot of the bath. The patient should be protected from direct contact with either plate by sitting upon a wooden framework. With a sufficiently powerful current, a portion of the electricity will pass through the body of the patient reclining thus between the poles. Another method is to connect the water with one pole, and for the patient to grasp in his unimmersed hands a copper bar covered with wet flannel, and in connection with the second pole of the battery; or a conductor from this second pole may be held almost, but not quite, in contact with any part of the body immersed in the water. Either the Voltaic or Faradaic current may be used. Ordinary water with the Faradaic current, but salt and water, or acidulated water, with the Voltaic.

[SN: General Faradization.]

Another more generalized application is that introduced by Beard and Rockwell, under the name of “General Faradization.” The patient sits with his naked feet upon a sheet of copper connected with one pole, while the other pole is connected by a moistened sponge with the left hand of the operator, who passes his disengaged hand, slightly moistened, over the muscles of the patient, and sometimes over his whole body. The current, I need hardly say, passes through the body of the operator before it reaches the patient, and the sensation he feels is his chief guide to its graduation.

[SN: Centralized Galvanization.]

Another general application is the “Centralized Galvanization” of the same authors, in which their object is to bring the whole central nervous system under the influence of the Voltaic current.

They place one pole--usually the negative--at the epigastrium and pass a large moistened sponge from the positive pole over the forehead and top of the head, along the inner border of the sterno-mastoid, from the stylo-mastoid fossa to the sternum, and down the entire length of the spine, from the nape of the neck to the sacrum. The brain, sympathetic and spinal cord, and the pneumogastric nerves are thus submitted to the influence of the current.

[SN: Localized Electrization.]

But the great majority of cases require--not a generalized, but a strictly localized application, and for the fundamental principles of all methods of localized electrization we are indebted to the late Dr. Duchenne (the “father of electro-therapeutics”), for before him no one had attempted any local application of electricity that could properly be so called. Indeed, to Duchenne may be fairly ascribed the very birth of medical electricity as a branch of therapeutics, and in the true and kindly words of the _Lancet_, when announcing his death:--“No field of work was ever seized upon with more eagerness; ever cultivated with more earnestness; or perhaps ever made to yield a better harvest than that which the discovery of induced electricity placed at the disposal of the man whose genius was the first to recognize, and his talents to secure, the opportunity it afforded. Taking his work at its lowest estimate, he was a man to whom medical science owes a large debt of gratitude, and whose memory deserves a warm tribute of regard.” Duchenne’s two test experiments, demonstrating the fundamental principles of his method, I will now repeat upon the posterior surface of my left forearm. I propose to arrest Faradism in the skin, without allowing it to stimulate the subjacent muscles. To do this it is necessary for the skin to be quite dry--moisture, as you know, being a conductor of electricity--and to make sure of sufficient dryness, I sprinkle the skin with a little starch powder. I now apply to the dry skin the dry metallic conductors of an induction instrument in action. I am afraid you cannot see, Gentlemen, the small sparks produced as the two electricities combine upon the cutaneous surface, or hear the slight crackling sound produced, but you observe no muscular contraction, and what I feel is a superficial and evidently cutaneous sensation. I now replace the dry conductors by well-moistened sponges. You observe that I have not altered the power of the current, but that there is energetic contraction of the extensor muscles. This is quite involuntary, and is due to the electric irritation of the branches of the motor nerves.

It follows from these experiments that we may, at pleasure, arrest electricity in the skin, and that without puncture or incision we may make the current traverse the skin, and concentrate its action upon subcutaneous organs. It was at one time objected that the muscular contraction was the result--not of irritation limited to the muscle or its motor nerves--but of reflex action; but Duchenne demolished this objection by a vivisection. Having removed the skin from the face of a living rabbit--to whom chloroform had been administered--he divided the facial nerve of one side only, in order that the muscles supplied by it might be cut off from all connection with the cord. He then applied electric excitation to each muscle of the face, alternately, on the two sides. The muscles contracted separately and equally on both sides. He then destroyed the brain of the same animal, in order to place the cord in a condition favourable to the production of reflex action, and again excited the muscles as before. The results were absolutely the same.[11]

Muscular electrization may be produced either--as I have just shown you--by placing the conductors upon the muscle itself, a procedure termed _direct_ or _intra-muscular_ electrization, or by exciting only the motor nerve trunk, which is termed _indirect_, or _extra-muscular_ electrization, and which we shall consider presently.

[SN: Different kinds of Rheophores.]

For direct excitation of the larger muscles it is convenient to use well-moistened sponges, contained in cylinders of different sizes, or metallic disks, covered with wet leather and having conveniently shaped handles. A useful size of cylinder is one such as this (see Fig. 13), having a depth of about 1-1/2 by 1-1/8 inches, which allows the sponge to fairly fill it, while in such forms as this--6 inches by 1--when the sponge is inserted the lower three-fourths of the cylinder is empty, and the conduction of the current liable to become imperfect. Such a cylinder as this, without any insulating handle at all, is worse than useless, and is a still persisting relic of the barbarous time when the patient was invariably electrized by causing him to hold the conductors one in each hand, a proceeding extremely dangerous in certain pathological conditions, and in other cases not likely to be of benefit to him. The insulating handles should be well hollowed out, that they may be used, lying comfortably between the fingers, when holding two in the same hand. The disk rheophore (see Fig. 14), a metallic button covered with wash-leather, is extremely useful; it has the advantage over the sponge of allowing firm pressure to be made without the inconvenience of water being squeezed out, while by using its edge it may be made to answer in the majority of cases for a pointed conductor, which is fitted chiefly for application to very small muscles, such as the interossei and some of those of the face. The wire is attached to the conductor by being screwed into the socket (see a′, Fig. 14). A conducting cord is very apt to get frayed at the point of juncture, and that the wire which I recommend is not open to this objection is not the least of its advantages. [SN: Direct Electrization.] In direct electrization the rheophores should be firmly pressed down upon all points of the surface of the muscle, that all of its fasciculi may be equally electrized. With the Faradaic current it is convenient to apply the rheophores, held in the same hand (see Fig. 15), for from twenty to thirty seconds, to every part of the surface of the muscle, or group of muscles, promenading them as nearly as may be in lines from the origin to the insertion of the muscles. If the rheophores are not held in the same hand care should be taken to keep them near to one another, for the tension or penetrating power of Faradism is so great, that without this precaution there will be liability to excite reflex action. With the interrupted Voltaic current this liability does not exist, and a better plan when using it is to hold the sponge from the positive pole stationary, near to the origin of the muscles, and to stroke or paint as it were the entire muscular surface with the sponge from the negative pole, gliding it in lines from the position of the positive. In using the constant Voltaic current both sponges must be held quite immovable, and so applied it differs altogether in its effects from the very same strength of current interrupted by moving the conductors. I will demonstrate these different applications upon the extensors of my left wrist and fingers--Faradism--Voltaism--Constant Current.

[SN: Indirect Electrization.]