Text: It has been demonstrated on various occasions that sound waves of different quality produce forms of various shapes, but this important fact is shown in a novel and interesting manner by a new instrument which has been invented called the Phoneidoscope. The phoneidoscope consists of a cylindrical L-shaped brass tube, to the horizontal portion of which is attached an india rubber tub and a wooden mouthpiece. At the termination of the vertical part of the instrument is a blackened brass disk, in which is an aperture. If the disk be now covered with a thin coating of soap and water similar to the preparation used in blowing soap bubbles, and a voice or instrument be sounded close to the mouthpiece, a curious effect can be perceived in the soap film at the other end of the instrument. The vibration of the molecules of air in the tube is transferred to the film, and bands of rainbow tinted color become apparent, varying in form as the voice or instrument changes, and assuming an endless variety of patterns. Change of pitch produces a noticeable alteration in the forms, and the same notes on different instruments are marked by variations in the patterns on the soap solution, the colors in which, as the tenuity of the film increases, become marvelously beautiful."

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Source: 71