FIGURES PRODUCED BY SOUND.
Stretch a sheet of wet paper over the mouth of a glass tumbler, which has a footstalk, and glue or paste the paper at the edges. When the paper is dry, strew dry sand thinly upon its surface. Place the tumbler on a table, and hold immediately above it, and parallel to the paper, a plate of glass, which you also strew with sand, having previously rubbed the edges smooth with emery powder. Draw a violin bow along any part of the edges, and as the sand upon the glass is made to vibrate, it will form various figures, which will be accurately imitated by the sand upon the paper; or, if a violin or flute be played within a few inches of the paper, they will cause the sand upon its surface to form regular lines and figures.