Modern Magic: A Practical Treatise on the Art of Conjuring

Pistons.--These are appliances for working pieces of mechanical apparatus--as, for example, the Watch Target, the Card Star, the Demon’s Head, etc., etc. A piston (see Figs. 277, 278) consists of a brass tube a, about five inches in length by five-eighths of an inch in diameter, with a collar at one end pierced with screw-holes for affixing it to the under surface of the table. Within this tube works a wire rod, b, three-sixteenths of an inch thick, and terminating in a small round disc of brass c, just large enough to work freely up and down the tube. A spiral spring, also of brass, keeps the rod down, unless when forced upwards by pulling a piece of whipcord, which is attached to the disc c, and thence passes up the tube, and over a small pulley d, which is soldered to the collar already mentioned. When this cord is pulled, b is forced to rise, which it does to the extent of about two inches above the surface of the table (see Fig. 278), again sinking under the pressure of the spring, as soon as the pull is relaxed. Each piston is screwed to the under surface of the top of the table, in which a small hole is bored, in order to allow of the upward passage of the piston rod. Where complicated mechanical pieces have to be worked, three, four, or more of these pistons are placed side by side. The cords are carried behind the scenes, either directly from the back of the table, or down grooves in the legs, and through holes in the stage to the hiding-place of the assistant. Where a single piston only is required, it may be made to work in the central pillar of a light guéridon, or fancy table, such as shown in Fig. 279, the lightness and simplicity of the table, and the thinness of its top, apparently precluding all possibility of the presence of concealed mechanism. The cord may be made to pass down the centre pillar, so as to be quite invisible to the audience.