Modern Magic: A Practical Treatise on the Art of Conjuring

ELECTRICAL TRICKS.--Some of the most mysterious of the stage tricks are performed by means of electricity, or, to speak more correctly, of electro-magnetism. In describing these, which are nearly all attributable to the inventive genius of Robert-Houdin, it may be desirable, in the first place, to explain in a few words what electro-magnetism is, and how it operates. Every school-boy is acquainted with the ordinary steel horseshoe magnet, and knows that if the accompanying small iron bar, or “keeper,” is placed within a short distance from its ends or “poles,” it will be sharply attracted to them. In the case of the ordinary magnet this attractive force is permanent, but in that of the electro-magnet it may be produced or destroyed at pleasure. The electro-magnet consists of a short piece of soft iron, (either straight, or bent into a horseshoe form), with copper wire (covered with silk or cotton) wound round and round it nearly to the ends. If a current of electricity from a galvanic battery is made to pass through this wire, the iron core becomes powerfully magnetic, the attractive force, however, ceasing as soon as the current is interrupted.