A thaumatrope is a toy that was popular in Victorian times.
A disk with a picture on each side is attached to two pieces of string. When the disk is spun quickly the two pictures appear to combine into a single image due to the optical property known as persistence of vision.
Examples of common thaumatrope pictures include a bare tree on one side of the disk, and its leaves on the other, or a bird on one side and a cage on the other. They often also included riddles or short poems, with one line on each side.
Thaumatropes were one of a number of simple, mechanical optical toys that took advantage of persistence of vision, but whose popularity faded with the development of motion pictures.
See also: Zoetrope, Optical illusion
