CHAPTER XIII.

VARIOUS APPLICATIONS-WORKSHOP OF THE
ELECTRICIAN.

A WHOLE book would be required to review entirely all the various applications of which electricity is susceptible, and which could not be classified under any of the foregoing headings. We can here only refer to a very few taken haphazard.

Physiological Actions of the Current-Medical Applications.-Electro-therapeutics are becoming every day more important in medicine, and in spite of the opinions so divergent which still divide practitioners, it may be hoped that before long, thanks to the introduction of precise methods and measuring apparatus into medical practice, the doses of electricity will cease to be quack, and become scientific and rational. However, the results already obtained are sufficiently important to justify their introduction into daily practice.

Electricity is employed in medical practice under two forms (1) continuous current; (2) alternating or induced

current.

Continuous currents are always produced by means of small batteries easy to move about and to renew; sulphate of copper or Leclanché batteries are very suitable for this application. They are coupled in tension by means of a commutator in the case holding them; a varying number may at will be taken according to the effects to be obtained, the nature of the disease, the parts to be affected, &c.

Alternating currents are obtained by means of a small

With the first the

Clarke machine, or an induction coil. power is modified by changing the speed, or by masking the magnet more or less. With the induction coil either the number of elements in the primary circuit may be varied, or the number of induced currents produced in a given time may be altered by regulating the speed of the trembler; or, finally, the quantity of electricity developed at each discharge may be varied by altering the distance between the primary and secondary coils.

It will be understood, so great a number of variable factors being given, that the logical and rational application of electricity to therapeutics becomes a complex, delicate, and difficult question, and the intervention of a practitioner is required to apply it judiciously.

Together with the direct use of the current, electricity is used in an indirect manner in a number of cases, such, for instance, as to localise the position of a bullet, the lighting of dark cavities, cauterisation, &c.; but the study of these applications cannot be gone into here.

The Training of Horses by Electricity.-Various means have been proposed to stop and master runaway or restive horses; there is nothing more ingenious and efficacious than that devised by Defoy, and of which M. Bella, manager of the French Omnibus Company, has had occasion to appreciate the advantages. This question cannot fail to be of interest to those fond of horses. The apparatus is simply a Clarke machine inclosed in a case, which may be placed convenient to the hand of the rider or driver. The reins contain conducting wires connected to the bit and to the magneto-electric apparatus. By turning the handle a current is sent through the mouth of the horse, giving it such a surprise that it stops and remains quiet. By coupling the action of the electricity with gentleness and petting the most dangerous horse will be rapidly mastered.

M. Bella reports that M. Defoy tried his apparatus in his presence at the yard of the General Omnibus Company (French), where the worst tempered and most dangerous horses were assembled. A gelding, very difficult to shoe,

was brought to the forge, where it showed excessive temper, but when supplied with the electric persuader, it, at the end of a few minutes, allowed its neck and back to be patted, then its limbs, and finally, the hind feet were lifted, always the most difficult to approach and to lift up. The shoe was hammered without the horse again becoming rebellious, says M. Bella, and its shoes were changed without being shackled, and without recommencing its dangerous defences.

The Director of the Paris Cab Company also certified to the efficiency of this process: "The experiment," says M. Camille in a report before us, was tried on several horses which up till then it was impossible to shoe, all, without exception, being tamed by the apparatus. One horse about to be shod, rolled about on the ground, kicking and struggling against everything, and nothing could subdue it. I had recourse to M. Defoy's apparatus; at the first trial the feet of the restive horse were, to my astonishment, lifted without great difficulty; at the second trial it was as easy to shoe it as if it had never offered any opposition; the animal was conquered."

M. Defoy drove a dangerous horse before us, which he stopped instantaneously after being set galloping, by turning the handle of a Clarke apparatus fixed under the seat of the vehicle, Fig. 148. It is important to state that the result is not due to a violent shock; the electric current is not strong enough to galvanise or stupefy the animal; it rather produces astonishment and the disagreeable but not painful sensation of electric pricking. We ourselves have very easily borne the current of the magneto-electric apparatus used by M. Defoy. There is nothing in the process on a par with the barbarous methods sometimes used to tame horses by force or violence, which tire them out, excite them, and make them wild and vindictive.

We will add that M. Defoy completes the electric bit with an electric stick not less ingenious than the first appaThis is a whip containing two insulated conductors, ending in two points at right angles to the end of the stick, and arc, as in the case of the bit, connected to a magneto

ratus.

FIG. 148.

electric apparatus. A horse in the habit of rearing may, at the moment it attempts to do so, be stopped by giving it the

The same effect

it at once starts forward with head down. may be produced on a shying horse, by applying the current to its jaw on the side towards which it attempts to shy, when it will at once be stopped. By means of an electric stick M. Defoy makes a horse obey him in a few seconds in a truly marvellous manner.

Edison's Electric Pen.-The electric pen is an apparatus by which marks are made on ordinary paper-not a continuous coloured mark as with ordinary pens and pencils, but a broken mark, formed by a great number of small holes pierced through the paper. These holes are made by a very fine steel point, which alternately goes in and out of a tube held in the hand, and which much resembles a metal pencil. This point is worked backwards and forwards very rapidly; it makes 180 strokes a second when doing no work. Each time it passes out of the case barely enough to be visible, but quite enough to pierce the paper. The writing is not so quick as with ordinary pens, but nearly as quick as that of a writer who takes time to shape his letters well.

pen by a small which is placed The point is at

The alternating motion is given to the electro-motor, very ingenious and simple, above the penholder, as shown by Fig. 149. the lower end of a rod which traverses the penholder, and which at its upper part ends in a fork pressing an excentric mounted on the axis of the motor. This excentric has three cams, and therefore sixty revolutions of the axis per second produce the 180 strokes just mentioned. This axis carries a soft iron plate acting as movable armature to a fixed electric magnet, before which it revolves rapidly, by means of a very simple commutator, which breaks the current twice per revolution. A fly-wheel, relatively heavy, surrounds this armature, which is a diameter to it, and it serves to give great regularity and steadiness to the motion of the

axis.

The electric current which gives life to this small apparatus is furnished by a bichromate of potash battery of two elements suitably arranged. The lids of the two cells are of ebonite plates, joined to a metallic central piece which slides