The Mysterious Voice.
“Some time ago,” says a correspondent of La Nature, “I was walking around in a side show in which were exhibited mechanical portraits, when I was surprised to hear myself called: ‘Monsieur! Monsieur!’ * * * I discovered that the voice came from a tin trumpet, which was held in the mouth of a negro’s head made of wood, and suspended by a small brass chain from semicircles of iron supported by a wooden frame” (Fig. 1). The effect produced on the spectators by this speaking head was one of universal astonishment, and no one was capable of solving the mystery. The arrangement for producing the illusion is very simple, however, and is thus explained by the writer above referred to:
FIG. 1.—THE SPEAKING HEAD.
A person hidden behind the scenes speaks into a tube two or three centimeters in diameter which runs from that point to the wooden frame, and in the interior of the horizontal and upright pieces of which it passes till it reaches the suspended head at A, as shown by the dotted lines, E, D, C, B, A. The voice thus transmitted is reflected from the sides of the trumpet, H, to the person holding a conversation with the head.
FIG. 2.—THE SPEAKING GLASS CASE.
This experiment, which is analogous to the one that precedes, was explained by Nicholson, in 1832, in his Journal de Physique. Although at first offered as a physical experiment, under the title of an “experiment in acoustics,” it has since changed name and master, and is now dignified by the imposing name of “invisible girl.”
FIG. 3.—THE INVISIBLE GIRL EXPERIMENT.
Fig. 2 shows the arrangement of the original apparatus, which consisted of a glass case, X, about four feet long by about one in height, suspended from the ceiling by four chains at a distance of a foot from the window frame. From the extremity of the case projected a speaking trumpet, and the entire apparatus was surrounded by a latticework of iron wire to prevent its being touched by the hands of the curious. The phenomenon, although a puzzling novelty at the time, did not attract much of a crowd, as it was not managed with sufficient address, and the surroundings were not of a nature to please fashionable people. This apparatus was improved upon and rendered more elegant in appearance by Prof. Robertson. Fig. 3, copied from an old engraving, shows this latter arrangement. A globe, A, made of glass or enameled sheet iron, and to which are attached four trumpets, is suspended from the middle of the room. This globe is not necessary for the experiment, but is only an accessory to impose upon the imagination. Around it is placed a framework, B, which is very necessary, for it is hollow, and it is through it that the voice of the invisible person is heard. A tin tube passes through the upright C and then runs to D, where there is a small slit or aperture opposite the trumpet. This tin tube passes under the floor of the room, and runs into the neighboring room, whence the pretended invisible person speaks, and sees everything through the keyhole or through an aperture in the wall. This is all there is of the mystery.