Optical toy:Magical Mirrors Optical Toy

Optical toys--playing with what the eye sees--have fascinated adults and children for centuries. The success of such devices relies on the phenomenon of "the persistence of vision," in which the brain retains the impression of an object for a fraction of a second after its disappearance, creating the possibility of apparent motion. Inventors of devices of optical illusion made by fracturing an image, by imparting a depth or three dimensions to an image, or by presenting a rapid series of slightly varied images to suggest movement offered entertainment for Americans in public spaces such as peep shows and lantern slide programs and in their homes using stereoscopes, zoetropes, and kaleidoscopes. And of course these early optical devices led to the development of moving pictures, a staple of a huge 20th-century entertainment industry.