It has a very strange name, but most of us have played or built one on occasion. The thaumatrope is an optical toy that is used to produce a sensation of movement in images. It consists of a disk with an image on each of its faces . Two strings or rubber bands are placed at the ends of the disc that twist a lot, so that, when stretched, the disc begins to rotate at full speed. The rapid turn creates in the viewer the optical illusion that both images are together.
The thaumatrope is believed to have been invented by John Ayrton Paris in the 19th century, with the intention of demonstrating to his colleagues at the Royal College of Physicists the principle of persistence of vision. This principle postulates that an image remains on the human retina for a tenth of a second before disappearing completely. The Thaumatrope in Paris showed pictures of a parrot and an empty cage, and turning it around created the illusion that the bird was in the cage.
This contraption, considered one of the forerunners of cinema , could have begun to be used much earlier than previously thought, as suggested by recent investigations with Palaeolithic remains found in the Lascaux cave (France).
