THE THAUMATROPE.
This word is derived from two Greek words, one of which signifies wonder, and the other to turn. It is a very pretty philosophical toy, and is founded upon the principle in optics that an impression made upon the retina of the eye lasts for a short interval after the object which produced it has been withdrawn. The impression which the mind receives lasts for about the eighth part of a second, as may be easily shown by whirling round a lighted stick, which if made to complete the circle within that period, will exhibit not a fiery point, but a fiery circle in the air.