Modern Magic: A Practical Treatise on the Art of Conjuring

SPIRIT-RAPPING.--This deception is frequently performed by the aid of electro-magnetism, although the raps may be, and in most instances are, produced by much simpler methods. We will suppose that a table is to be the instrument of the raps. The top being removed, a hollow is made in the “frame” which supports it, and in the cavity thus made is fixed an electro-magnet, of the fashion shown in Figs. 304, 305. Upon one side of the horseshoe, at the centre of the curve, is screwed a brass spring a, to the opposite end of which is attached the keeper b. The effect of the spring is to hold the keeper about a quarter of an inch away from the poles of the magnet, save when a current of electricity is made to pass through the wire, when the horseshoe becoming magnetic, the keeper, in spite of the resistance of the spring, is brought down sharply into contact with the poles, and so remains until the circuit is again severed, when it flies back again to its former position. The little metal knob or hammer c, which is to produce the raps, is screwed to the under side of the keeper, and points between the two arms or poles of the magnet. If, therefore, the magnet be fastened to a piece of wood, or other hard surface, and an electric current be sent through the wire, the keeper is instantly drawn down to the poles of the magnet, and the hammer, moving with it, strikes the wood between the poles, and produces the rap. As soon as the circuit is broken, the keeper and hammer are raised by the spring, in readiness for another rap; and each time that connection with the battery is made, a rap is produced. The wires from the concealed magnet are made to pass down the leg of the table, and beneath the floor or carpet to the hiding-place of the assistant, who can thus summon spirits “from the vasty deep” or elsewhere, at his pleasure.