A Phoneidoscope
The phoneidoscope has many and varied forms, but the simplest can be made by bending the forefinger and thumb so as to form a circle and then drawing a soap film across the opening. This is done in a manner similar to the blowing of soap bubbles. The angle with the direction of the light may be readily adjusted by turning the wrist, a motion of the elbow alters the distance from the mouth and the tension of the film can be regulated by moving the thumb and forefinger. Singing or speaking at the film when under proper tension will cause beautiful figures to appear, which may be reflected from the film directly on the screen.
Contributed by Robt. E. Bradley, Winchester, Mass.