Modern Magic: A Practical Treatise on the Art of Conjuring

To describe completely the “induction coil,” above referred to, would be beyond the scope of the present treatise. It may, however, be summarily described as consisting of a coil of insulated copper wire, wound round a small bundle of straight iron wires, say five or six inches in length, and an inch in diameter. This is called the “primary” coil. Round this is again wound a quantity of much finer wire, also insulated. This constitutes the “secondary” coil. The ends of each coil are kept free. If a current of electricity be made to circulate through the wire of the primary coil, an independent current of great intensity is found to be thereby produced, by a mysterious process called induction, in the secondary coil. This current is strongest at the moment of first completing the circuit in the primary wire, and if a person is grasping the ends of the secondary wire, or any conducting substance in connection with it, at the moment when the circuit is completed, he will receive a very severe shock. A contrivance is attached to the coil, whereby the circuit is made and broken alternately with great rapidity, thereby producing a continuous shock, of such power that the victim loses for the time being the faculty of relaxing his muscles, and is compelled, after the manner of the unfortunate Arab, to grip, tighter and tighter, the cause of his pain, until released by the final severing of the circuit. Any reader who desires a more complete acquaintance with the induction coil, should purchase a little shilling manual, entitled, “Intensity Coils, How Made and How Used,” by “Dyer” (Suter, Alexander, and Co., Cheapside), where he will find an excellent account of this interesting subject.