The inspiration for the development of motion pictures and projectors can be traced to a variety of sources including theaters, circuses, and magic shows. Another important factor was the understanding of the phenomenon of persistence of vision. While the process was known for hundreds of years, it was only in the early nineteenth century when Roget introduced the under-lying theory in an article that it developed popular interest. In short, persistence of vision is the phenomena in which the brain retains an image that is observed by the eyes for slightly longer than it is actually seen. Movies take advantage of persistence of vision to create the illusion of motion. When successive still frames are viewed, the brain "connects" the image and they appear to move.
During the early 1800s, hundreds of novelty devices based on this principle were introduced. Some of the most influential include the Thaumatrope and the Phenakistiscope. Dr. John Ayrton Paris is generally regarded as having invented the Thaumatrope in 1825. This device was a toy with a simple design that took advantage of persistence of vision. It consisted of a small round board with a picture on both sides. The original toy had a bird on one side and a cage on the other. The board was held at the side by two strings and when spun it appeared as though the bird was in the cage.
The Phenakistiscope was introduced in 1832 by Joseph Antoine Ferdinand Plateau. This toy was a disc with a fixed center that allowed it to be spun freely. Various images were drawn on the outer edges of the disk depicting sequential movement. The pictures were spaced evenly and slits were cut in conjunction with each. The toy was held between the user and a mirror and images were viewed reflected by the mirror. The persistence of vision created the illusion of movement. Plateau was the first to realize that there had to be a resting period between images for a perfect illusion and determined that 16 images per second...