MOVING PICTURE MACHINES

The Zoetrope and praxinoscope are examples of optical devices that produce an illusion of motion. Both instruments were designed in the first half of the 19th century, along with other instruments that preceded the onset of the cinema. They have been used for vaudeville and enjoyed with a great interest in both Europe and America.

The Zoetrope consists of a large hollow cylinder into which a cartoon strip made up of a few simple images is inserted. The images – mostly twelve – show successive phases of a movement such as an acrobat jumping over a hoop. A corresponding number of thin vertical slits are cut around the perimeter of the drum which allows the viewer to see the images inside the drum. After spinning the drum, the images seen through the slit will fuse together and what is a sequence of separate, stationary images evokes the perception of motion. The movement speed varies with the speed of the drum rotation; slow rotation disrupts the illusion. In a praxinoscope, the peepholes in the middle of the drum are replaced by mirrors that reflect the images around the perimeter.

For a Czech visitor, it may be interesting to note that one such clever visual toy working on a similar principle proposed Jan Evangelista Purkyně. His kinesiscope is an improved version of the so called fantascope, in which one sees a phased image through a slot in a mirror drawn on the far side of the rotating circle. Purkyně replaced the mirror with a second circle with synchronized movement. He was also probably the first person to use a similar device for instructional purposes – using it to demonstrate a throbbing heart and blood circulation.

The illusion of motion when viewing a sequence of still images has long been explained by ‘persistence’ so that the image of the first stimulus remains in the eye for a short time and its perception overlaps with the image that follows. This explanation, however, was later proved wrong, and it seems more likely that the timing of the presentation of each image corresponds to the time needed for the synthesis of partial information of the stimulus in the brain.

/ Haroldson, D. (1975). Creators of Life: A History of Animation. New York: Drake Publishers. /