In addition, however, to these troubles we may have external injuries produced. Even in cases where the current amounts to not more than a few milliamperes burns may be caused by the ordinary electrodes of the galvanic battery. The faradic current when medically used does not, as a rule, produce any external injuries. Such might be caused by a spark from a static machine, but it would be due to gross carelessness, and is very unusual. Burns, however, from the use of the galvanic current are not very uncommon. They usually occur under the electrode after it has been for a few moments stationary in contact with the skin. They occur in certain patients with extraordinary readiness, especially in those with organic spinal lesions, and where the sensation is somewhat diminished, and where also some trophic lesion might be supposed to exist. They are not confined, however, to this class of cases, but may occur in any one if the electrode be retained too long in any one place, and especially if it be allowed to become dry. These burns are peculiar in appearance and can usually be recognized at once. They are circular, as if punched out, about the size of a common pencil or a little smaller, comparatively deep, gray with perhaps a dark ring at the circumference, and frequently surrounded by a reddened area. The edges are sharp. Their peculiarity consists (1) in their painlessness and (2) in their size, regular form, their depth in comparison to their extent, and the sharp limitation of the area of tissue destroyed. One or more may occur under a broad electrode, and they are probably produced at those points where the contact is imperfect or the conduction in some other way impeded. They heal without much difficulty and leave no serious results.
Other unpleasant symptoms produced by currents in medical use may be mentioned for the sake of completeness, and also as an introduction to the more serious symptoms caused by stronger currents. Dizziness, vertigo, tinnitus, nausea, vomiting, and syncope are readily caused by even slight currents. The sensation of light in the eyes and the metallic taste in the mouth are the results of medical currents of ordinary strength when applied to the head or in its neighborhood, and stronger currents applied at greater distances cause these sensations. All the above symptoms may be readily caused by even slight currents, whether galvanic or faradic, passed through the head. The syncope thus produced is to be carefully differentiated from the syncope caused psychically by excitement or fear of the application of electricity. Hysterical women, and even persons who show no special signs of nervous instability, may faint at the suggestion of the application of electricity. I have seen a large, strong, well-built Italian man, perfectly sound physically, so far as could be detected, except some slight local neuralgia, faint from pure fright when the electricity was to be applied. But even the application of moderately severe shocks from the ordinary medical battery are not likely to produce serious results. These shocks are ordinarily caused by the opening or closing of the galvanic current, and are most severe when the current passes through some portion of the head. A still more powerful shock may be given by reversing the current in a galvanic battery by means of the commutator.
Currents of High Tension—Strong Artificial Currents.
Passing on now to the consideration of the stronger currents, we come to those used for mechanical purposes, for electric lighting, electric railways, and other analogous objects. These currents start from dynamos or from storage batteries, and accidents are caused by them whenever they are diverted from their proper course and are caused to come in contact with or to pass through any portion of the human body in any considerable strength. Accidents not infrequently occur from direct contact with the batteries or dynamos, but still more frequently they are produced in their circuit along the wires or transmitters. They may also be caused, as some of the most fatal have been, by contact with metallic or other readily conducting objects which have themselves accidentally come in contact with some portion of an electric circuit (usually wires) and have diverted the whole, or more usually a portion, of the current to themselves. Thus was killed a young man in New York, the clerk in a store, who while lifting the metal-edged cover of a show-case brought it in contact with the charged wires of an electric light and received an immediately fatal shock. As a rule, those meeting with accidents from dynamos or electric machines directly are employees of electric companies, who are presumed to have more or less knowledge of the risk of carelessness, or they may be workers in institutions or factories in which such machines are in use. Many of the accidents due to wires also occur to linemen and other employees of electric, telephone, or telegraph companies or of electric railway companies in charge of wires or electric outfit. So long as the current transmitters and terminals (wires, etc.) are properly insulated and in their proper position in relation to other conductors, it is unusual for accidents to occur, except in cases of gross ignorance or carelessness. Unfortunately, however, proper insulation is not always accomplished, and frequently wires and other transmitters are removed from their proper positions by accidents and otherwise. So long as and wherever the system of overhead wires exists, if there be among these wires any which are the transmitters of strong electric currents, there is always a risk, and often a very serious one, that at some time or other one of these current-bearing wires will come into contact with some other non-current-bearing and ordinarily harmless wire in such a manner that the current of the first should be diverted, in whole or in part, on to the ordinarily innocuous wire, which thereby becomes at once charged and dangerous. Such an accident may be due to the displacement of either wire or to any other cause which brings the two in contact, either direct or indirect, at a point where the current-bearing wire is not sufficiently insulated. The current having once passed out of its proper circuit will, of course, follow the paths of best conduction, and may hence suddenly appear in unexpected quarters and produce the most dangerous and even fatal effects. It is accidents of this character which most frequently occur among the people who are neither employees of electric companies nor engaged in factories or buildings where electrical machines are employed.
Insulation of Wires and Other Electrical Transmitters.—We cannot mention here the various methods employed to insulate wires, as the general principles of insulation are well known. Electric wires even with very strong currents can be insulated and can be kept insulated if sufficient pains be taken and sufficient money be expended. But this is very expensive and in many cases is not done. Only partial insulation is attempted, and even this is not always carried to the degree intended or stipulated. Hence so long as overhead wires of various kinds exist, accidents from the transmission of strong electric currents along ordinarily harmless wires are liable at any time to occur, as practically little or no attempt at keeping the current-bearing wires covered with a thoroughly insulating material is in most cases made. It is usually deemed sufficient that glass or other insulators should be so placed that under ordinary conditions the wire will not come into contact with any conductor which may cause any essential part of its current to diverge. In most cases a so-called insulating material is placed over the wire itself, but this usually is insufficient at the outset or becomes so before very long and is then not renewed.
It must not be supposed, however, that underground electric wires or transmitters cannot produce accidents. On the contrary, the current may be diverted from them to the gas or water pipes or to any other conductors which come into contact with them or can attract to themselves a portion of their current. Severe shocks have been experienced by persons attempting to draw water at their faucet from causes of this character. At the same time, so far as mere safety is concerned and freedom from electrical accidents, it would seem that underground wires are preferable to overhead wires.
Electrical wires have not infrequently come in contact with telegraph and telephone wires causing unpleasant results. Telephone boxes have been set on fire, and also telegraph boards and tables, and in certain cases what might have been serious conflagrations have been started in this manner. By means of proper arrangements on the telegraph and telephone circuits these dangers can be at least partially avoided, but there is always the risk that the automatic alarms and other contrivances do not act, and the still greater one that persons or things may come into contact with these charged wires and receive dangerous or serious injuries.
Electric Cars.—The danger from the overhead wires in the trolley system of electric cars would not be great were these wires properly supported, properly insulated, and properly protected. Each of these terms must be explained. Wires which fall for any cause whatever short of being intentionally removed cannot be deemed properly supported in the sense in which we use the term. Any one of these electric wires which falls is liable to produce serious injury to persons or animals (many horses have been killed by them), or to set fire to objects with which it comes into immediate or indirect contact, the amount of injury being in part dependent upon the nature and the condition (wet or dry) of the object and its position in relation to other conductors. Wires as dangerous as these car wires should be so supported that no ordinary accident, no condition of the weather, strong winds, or heavy falls of snow should be capable of wrenching them from their supports, and they should be placed in such positions and with such protection as not to receive blows from passing or falling objects.
Secondly, these wires should be properly insulated. This is to be understood to mean that all the wires which carry the electric current, or are liable to carry it, should be attached to their poles or other support in such a manner that no appreciable quantity of electricity is under any circumstances liable to be diverted to the poles or supports, and in this way cause destruction or injury. In addition to this the side wires should be so covered that if any accident occurs, it will be difficult or impossible for the current to pass away from them to other objects. The middle wire on which the trolley runs cannot be thus covered, but must be left bare, and hence, if knocked down or brought into contact with properly conducting objects, must be the most dangerous; but on the other hand from its position it is less liable to accidents.