The facility with which the voice circulates through tubes was known to the ancients, and no doubt has afforded the priests of all religions means of deception to the ignorant and credulous. But of late days the light of science dispels all such wicked deceptions. A very clever machine was produced at Paris several years ago, and afterwards exhibited in New York and other cities in the United States, under the name of the "Invisible Girl," since the apparatus was so constructed that the voice of a female at a distance was heard as if it originated from a hollow globe, not more than a foot in diameter. It consisted of a wooden frame something like a tent bedstead, formed by four pillars a a a a, connected by upper cross rails b b, and similar rails below, while it terminated above in four bent wires c c, proceeding at right angles of the frame, and meeting in a central point. The hollow copper ball d, with four trumpets, t t, crossing from it at right angles, hung in the center of the frame, being connected with the wires alone by four narrow ribbons r r. The questions were proposed close to the open mouth of one of these trumpets, and the reply was returned from the same orifice. The means used in the deception were as follows: a pipe or tube was attached to one of the hollow pillars, and carried into another apartment, in which a female was placed; and this tube having been carried up the leg or pillar of the instrument to the cross-rails, had apertures exactly opposite two of the trumpet mouths; so that what was spoken was immediately answered through a very simple mode of communication.
THE MAGIC OF ACOUSTICS.
The science of Acoustics furnished the ancient sorcerers with some of their best deceptions. The imitation of thunder in their subterranean temples could not fail to indicate the presence of a supernatural agent. The golden virgins whose ravishing voices resounded through the temple of Delphos,—the stone from the river Pactolus, whose trumpet notes scared the robber from the treasure which it guarded,—the speaking head which uttered its oracular responses at Lesbos,—and the vocal statue of Memnon, which began at the break of day to accost the rising sun,—were all deceptions derived from science, and from a diligent observation of the phenomena of nature.
Take a long piece of wood, such as the handle of a hair broom, and placing a watch at one end, apply your ear to the other, and the tickings will be distinctly heard.
TO SHOW THAT SOUND DEPENDS ON VIBRATION.
Touch a bell when it is sounding, and the noise ceases; the same may be done to a musical string with the same results. Hold a musical pitchfork to the lips, when it is made to sound, and a quivering motion will be felt from its vibrations. These experiments show that sound is produced by the quick motions and vibrations of different bodies.