This section is from "Scientific American Supplement". Also available from Amazon: Scientific American Reference Book.
"There is nothing new but what has been forgotten," said Marie Antoinette to her milliner, Mdlle. Bertin, and what is true of fashion is also somewhat so of science. Shoeing restive horses by the aid of electricity is not new, experiments thereon having been performed as long ago as 1879 by Mr. Defoy, who operated with a small magneto machine.
But the two photographs reproduced in Figs. 1 and 2 have appeared to us curious enough to be submitted to our readers, as illustrating Mr. Defoy's method of operating with an unruly animal.

The battery used was a small Grenet bichromate of potash pile, which was easy to graduate on account of the depth to which the zinc could be immersed. This pile was connected with the inductor of a small Ruhmkorff coil, whose armature was connected with a snaffle-bit placed in the horse's mouth.

This bit was arranged as follows (Fig. 3): The two conductors, which were uncovered for a length of about three centimeters at their extremity, were placed opposite each other on the two joints of the snaffle, and about five or six centimeters apart. The mouth-pieces of the bit had previously been inclosed in a piece of rubber tubing, in order to insulate the extremities of the conductors and permit the recomposition of the current to take place through the animal's tongue or palate.
Each of the bare ends of the conductors was provided, under a circular brass ligature, with a small damp sponge, which, surrounding the mouth-piece, secured a perfect contact of each end of the circuit with the horse's mouth.

The horse having been led in, defended himself vigorously as long as an endeavor was made to remove his shoes by the ordinary method, but the current had acted scarcely fifteen seconds when it became possible to lift his feet and strike his shoes with the hammer.
The experimenter having taken care during this experiment to place the bobbin quite near the horse's ear, so that he could hear the humming of the interrupter, undertook a second experiment in the following way: Having detached the conductors from the armature, he placed himself in front of the horse (as shown in Fig. 2), and began to imitate the humming sound of the interrupter with his mouth. The animal at once assumed the stupefied position that the action of the current gave him in the first experiment, and allowed his feet to be lifted and shod without his even being held by the snaffle.
The horse was for ever after subdued, and yet his viciousness and his repugnance to shoeing were such that he could only be shod previously by confining his legs with a kicking-strap.
It should be noted that the action of the induction coil, mounted as this was, was very feeble and not very painful; and yet it was very disagreeable in the mouth, and gave in this case a shock with a sensation of light before the eyes, as we have found by experimenting upon ourselves.
From our own most recent experiments, we have ascertained the following facts, which may guide every horse-owner in the application of electricity to an animal that is opposed to being shod: (1) To a horse that defends himself because he is irritable by temperament, and nervous and impressionable (as happens with animals of pure or nearly pure blood), the shock must be administered feebly and gradually before an endeavor is made to take hold of his leg. The horse will then make a jump, and try to roll over. The jump must be followed, while an assistant holds the bridle, and the action of the current must be at once arrested. After this the horse will not endeavor to defend himself, and his leg may be easily handled.
(2) Certain large, heavy, naturally ugly horses kick through sheer viciousness. In this case, while the current is being given it should be gradually increased in intensity, and the horse's foot must be seized during its action. In most cases the passage of a current through such horses (whose mucous membrane is less sensitive) produces only a slightly stupefied and contracted position of the head, accompanied with a slight tremor. The current must be shut off as soon as the horse's foot is well in one's hand, and be at once renewed if he endeavors to defend himself again, as is rarely the case. It is a mare of this nature that is represented in the annexed figures.
We know that this same system has been applied for bringing to an abrupt standstill runaway horses, harnessed to vehicles; but knowing the effect of a sudden stoppage under such circumstances, we believe that the remedy would prove worse than the disease, since the coachman and vehicle, in obedience to the laws of inertia, would continue their motion and pass over the animals, much to their detriment. - Science et Nature.
 
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