In one method the lady has a hole, one and a half inches in diameter, cut out of the sole of one of her slippers. (Fig. 23.) She places this foot over a hole in the stage, through which a small piston is worked pneumatically by the assistant. The piston is connected with a rubber tube, which runs to where the assistant is concealed. The assistant looks at the blackboard and manipulates the bulb, thus causing the piston rod to strike the sole of the foot, giving signals which can be readily understood by the subject. Robert Heller used a system somewhat similar, only an electro-magnet was used instead of the pneumatic piston.
Fig. 24.—The Speaking Tube.
Another and bolder method of conveying information is the speaking tube. In this case a Vienna bent-wood chair is used. The chair is specially prepared for the trick. One leg of the chair is hollow, and the air passage is continued to the very top. The lady usually has a long braid of hair hanging down her back, and, if not blessed by nature with this hirsute adornment, she wears a wig. In either case, concealed in the hair is a rubber tube, one end being close to the ear and the other hanging down with the braid, so that when the lady is seated on the chair the operator can easily connect it with the tube in the chair. (Fig. 24.)
Fig. 25.—The Head Telegraph.
Fig. 26.—The Signaling Instrument.
There is still a third method, which is so absurdly simple that it deceives even a very knowing committee. The committee places a chair on any part of the stage they may see fit, and the subject seats herself and is blindfolded as before. A thread runs from the side of the subject through a small ring attached to a chandelier overhead. (Fig. 25.) One end of this thread is held by an assistant and the other end is fastened to a hammer working on a pivot secured to a metal plate concealed in the hair of the lady, her hair being dressed high. When she walks on the stage, the assistant pulls in the slack of the thread, and when she is seated on the chair, the assistant pulls the thread taut, so that he is able to communicate signals to her by a very slight motion of the thread, which causes the hammer to work on the plate, which is resting very close to the skull, so that the signals are easily felt at every stroke of the hammer. (Fig. 26.) Predetermined signals may be used, or the regular Morse alphabet, as in telegraphing. There are a number of other ways of convey conveying information, but the three methods we have described are perhaps the best.