THE ANIMATED CRYSTAL.
Alum put into a tumbler of water, as it dissolves will assume the shape of a pyramid. When the solution has nearly terminated, you will find the mass covered with geometrical figures, cut out, as it were, in relief upon the mass. This experiment having succeeded, take up a crystal quartz which has six sides, and cut accurately from each face to a perfectly convex surface, and place it on a piece of plate or common window glass, a china or glazed plate, or any smooth surface, perfectly clean, as grease or a particle of dust would impede its motion. Wet the surface, and give the plane a slight inclination, when, if properly managed, a rotatory motion will commence, which may be kept up for any length of time by giving alternate inclinations to the plane surface, according to the movements of the crystal; to heighten the pleasing effect of which, a variety of paper figures, harlequins, waltzers, &c., may be attached. The first trial of the experiment had better be made by giving a slight rotatory motion to the crystal.