The Phenakistoscope

Phen • a • kist • o • scope:  n.  

An early animation device which employs the principal of vision persistence to create an optical illusion of motion. 

Officially invented in 1841 by Joseph Plateau of Belguim, Phenakistoscopes consisted of a spinning disc attached to a vertical handle, with a series of pictures painted on the backside...

The resulting animation is something of a marvel.

  

According to Wikipedia:

Arrayed around the disc's center were a series of drawings showing phases of the animation, and cut through it were a series of equally spaced radial slits. The user would spin the disc and look through the moving slits at the disc's reflection in a mirror. The scanning of the slits across the reflected images kept them from simply blurring together, so that the user would see a rapid succession of images that appeared to be a single moving picture.

I encourage you to visit DickBalzer's webpage where you can trip out on lots more crazy optical illusions.  The Thaumatropes alone are worth a look.
{ via, and, and }