THE EFFECTS OF ELECTRIC CURRENTS OF HIGH

POWER UPON THE HUMAN BODY.

BY

ALLAN MCLANE HAMILTON, M.D., AND GEORGE DE FOREST SMITH, M.D.

THE utilization of electricity nowadays is too general and familiar to need extended comment; suffice it to say that an agent that until a quarter of a century ago was used only for the operation of the telegraph, in electrometallurgy and other chemical processes, and in medicine, to-day provides a large part of the motive power, light, and heat of towns and cities throughout the civilized world, while in our own country the smallest villages are equipped with electric-light and street-car plants, and before another decade is finished electricity is likely to find its way into every household for some economic purpose.

Incident to its adoption it is natural that the use of so potent and dangerous an agent should have been attended by accidents more or less grave, due sometimes to want of familiarity upon the part of those who were engaged in providing it, or in its application, and of consumers who were for the most part entirely ignorant of its properties or manipulation. These accidents have so far not found their way into courts as the basis of litigation except to a limited degree, though there is no reason why the responsibilities of electric corporations differ from others where injury or death has been the result of negligence. The determination of culpability is, however, much more difficult, and contributory negligence is naturally claimed with some reason where the regulations and instructions are not complied with, or where the bodily harm is the result of foolhardiness upon the part of the injured person.

The properties of electric currents should by this time be well enough known to fix the blame where it belongs-either upon the victim, the power-providing or subway companies, or those who supply or maintain imperfect apparatus or poorly insulated conductors, or exact dangerous services from their employees, or in any way expose others to risk of life or limb.

The mechanical causation of accidents is a subject that is fully gone. into by writers upon electricity, and it is only necessary to say that where more or less serious harm has resulted it has been through imperfect conductors or insulations, when the person places himself in the circuit, receiving a much more powerful current than he expected, or where as the result of underground leakage a current of high voltage has been turned where it does not belong, either traversing wires designed for

currents of lower voltage or finding escape through iron water or gas pipes which the victim grasps. Again, the person places himself in the circuit of a current of great amperage, so that he is burned.

The effects of the passage of an electric current of high power through the human body are exceedingly variable and uncertain. sometimes produces instant death and again no result whatever. As will be seen later, nervous shock, more or less severe burns and a variety of minor nervous disorders may follow.

Modifying Conditions.-What is a current of high potentiality and what are the conditions which antagonize its effects? The voltage sufficient to produce death is commonly fixed at 1500 volts, yet cases are reported where very much more was received without fatal consequences, but in these cases it is probable that the entire current did not enter the body. In the determination of the strength of the current we are to consider the element of surface resistance, remembering Ohm's law that the intensity varies chiefly with the electromotive force and inversely with the resistance. The conditions of moisture and the pressure of metal fastenings increase the danger, while it is likely that it is somewhat diminished by the dryness of the hands or the interposition of nonconducting substance.

Gaertner and Edison found the resistance of the body when the surface was denuded to be from 1600 to 2000 ohms, but this is probably much greater. The effects of the alternating and direct differ greatly, a voltage of from 250 to 800 of the alternating killing a dog which withstood a continuous current of 1000 to 1400. The rapidity of the alternations also increases the fatality. It would seem that sudden interruptions have much to do with the serious effects, for a sudden break of the continuous current, say of 500 volts, is likely to produce much more decided effects than where no break is produced.

"The problem of the electromotive force is by no means so simple as it would appear from the ordinary statement that the current used was one of 500 or of 2000 volts. In the early days of Faraday's researches he was asked why a shock was felt when a circuit containing an electromagnet was broken, and why no shock was felt when the circuit contained neither electromagnet nor wire coil. This led Faraday to study what he called extra currents, but which are now spoken of as currents of selfinduction or inductance.* If the circuit contains a coil of wire it is found that on making closure a current of brief duration is induced in that wire, which runs in the opposite direction to the steady current. On opening the circuit another current, running in the same direction, is induced in the circuit. These extra currents, or currents of self-induction, were carefully studied by Blaserna,† who found that the extra current of opening was of shorter duration but much more intense than the extra current of closing, Now every dynamo-current necessarily contains a coil in its circuit, and consequently must present the phenomena of inductance. Hence when a person receives a shock from a dynamo-current he must also get, when the current is broken, a self-induced or extra current of opening, of great intensity but short duration. The strength of this extra current depends on so many factors that it is not easy to

* Fleming, The Alternate-Current Transformer, pp. 37 et seq. London, 1889. + Blaserna, Giornale di Scienze Naturali ed Economiche, vol. vi., p. 22, 1870.

calculate, but I understand that with a current of 500 volts it may reach 2000 or 3000 volts.

"It follows, then, that where the factors in the problem are so variable we cannot make any positive assertions and say that because A received a shock from a 2000-volt current without harm it must be harmless to B, when we know neither the body resistance of A or B, nor what part of the current A received. As well say that because A swallows ten grains of morphine and survives, ten grains is a safe dose to give to B." (Knapp.)

Effects of Discharges that do not Kill.-Slight shocks may result in pains, numbness, paresis, or swelling of an extremity; headache, vertigo, insomnia, and disturbed vision. Of course all such cases must be studied by themselves, for the temptation to exaggerate some of the subjective symptoms is very great. Persons who have been subjected to shock are sometimes worse during electrical atmospherical disturbances, their aches and pains and nervousness being exaggerated by a thunderstorm. These symptoms are usually recoverable, though there may be a variety of residual shock, with deep-seated nervous disturbance of an emotional kind, which obstinately persists. Dana is of the opinion that electrical currents when they do not kill produce no permanent harm, but this, we believe, is not always the case. The immediate effects of a strong non-fatal current (300 to 1000 volts) are temporary tetanus, the victim falling, with preservation of consciousness, but a sense of terror and pain which disappears with the rigidity. Of course the unexpected plays a part in the demoralization. A large number of residual conditions are left after electric shock. These vary from nervrosism and the condition which is known as the traumatic neurosis (see Dana's article) to light hysteria. The demoralization that remains after railway accidents is sometimes witnessed in these cases, and the resemblance to this kind of disorder is very close. In hypochondriacal persons the nervous excitement is extreme, and an excellent case of Knapp's may be used in illustration to show how powerfully the imagination may be excited when there is no actual injury but simply fright:

"I was asked by Dr. D. W. Cheever to see George L., forty-two, married, a coachman, who was said to be suffering from an electric shock. I saw him on April 14, 1889, and obtained the following history of his accident: He had always been well and strong, although slightly hypochondriacal; had used alcohol pretty regularly, although never to excess. He had been in one or two serious runaway accidents, and had conducted himself with marked coolness, judgment, and courage. Five days ago, on the 9th, a wet day, he was driving a span of horses attached to a coupé, and about 10.30 A.M. one or both of the horses stepped on the conduit of the West End Street Railway, which, from some defect in construction, had become charged with the electric current used in running the cars, claimed to be 500 volts, but probably greater. The horses got a shock, dropped, and lay squealing and struggling for a moment. As they fell, the driver, who was sitting on the box holding the reins, says that his hands felt numb and queer, and prickled and tickled. He jumped down, and thinks he stepped on the conduit; at any rate he felt a shock and a prickling sensation like needles in his legs, which was worse than in his arms, but neither shock was painful. He wore ordinary sewed single-soled shoes, with iron nails only in the heels. He thought he did

not touch the conduit with his hands, but he may have touched the tire of the wheels, although he felt no further shock; he cannot say whether he knelt on the conduit. He saw no sparks before his eyes and had no queer taste in his mouth. He sprang to the coupé, after alighting, and got the horses loose, and they started and ran to the stable. A friend who helped him move the carriage felt a slight shock, which was not painful. L. was very much excited and felt that he could not go after the horses. He did go to a house some two blocks away to tell his employer of the accident. In doing so he had to take a friend's arm, as he had severe pain in the knees, especially in the knee-caps. He then returned to the scene of the accident, where he met the stable-keeper, who had come in a buggy to see what the matter was. L. got into the buggy, helped take the coupé to the stable, and then went home. Since that time he has stayed in the house most of the time, being unable to do anything. He has been extremely nervous and apprehensive, and for two days had the feeling of pins and needles in his feet, and cramps in the calves of his legs at night, with occasional pain in the knees; but he has had no pain in the knees since the 12th. He has occasionally an aching pain in the back. He has a general shivery feeling, but does not feel cold or sick. He had a little headache on the 9th and the 13th, but not enough to amount to anything. He feels a little dizzy on stretching. There is no trouble with vision. Sleep has been very poor until last night, when he slept pretty well under thirty grains of bromide. He has been kept awake by a nervous feeling, and when he did fall asleep would start. Night before last he shook all night. To-day he has a slight pain across the epigastrium. He has had no sexual desire since the accident. Since his accident he has had a constant tremor, most marked in the hands; this is rather better to-day. When he came home he could not put his toes down to the floor very well. The calves now feel a little stiff.

"L. is stout, ruddy, and the picture of vigorous health. He is very nervous, apprehensive, and restless, constantly rubbing his hands together. He fears that he will never be able to work again or be the man he was before. There is a tremor of the head and limbs, most marked in the hands; this tremor is slightly increased in the arms on intended movements. The grip is not very strong, but there is no ataxia or Romberg's symptom, and he walks well. The tactile sensibility seems a trifle blunted all over the body, possibly more on the left side of the face than on the right, but there is no distinct line of division and no true hemianææsthesia to touch. The field of vision, as tested by fingers, seemed slightly contracted on the right. All movements were well performed. There was slight tenderness over the calves and the fourth dorsal vertebra, and rather more tenderness over the upper lumbar vertebræ. The knee-jerks were exaggerated; there was front tap contraction, and a tendency to a patellar clonus. There was no real clonus either at the patella or ankle, but a tap caused several contractions and a general muscular spasm. Examination of chest negative; pulse 106. No electrical tests were made.

"April 16. Sleeping better; tremor almost gone. Complains of soreness in the back. Goes out a little, but is unable to do any work.

"May 30. Getting on well. Still has a slight tremor in the right hand. Knee-jerks normal. Says he is not the same man, and is rather despond