Thaumatrope

A thaumatrope is an optical toy that was popular in the 19th century. A disk with a picture on each side is attached to two pieces of string. When the strings are twirled quickly between the fingers the two pictures appear to blend into one due to the persistence of vision.

Examples of common thaumatrope pictures include a bare tree on one side of the disk, and its leaves on the other, or a bird on one side and a cage on the other. Many classic thaumatropes also included riddles or short poems, with one line on each side.

Thaumatropes can provide an illusion of motion with the two sides of the disc each depicting a different phase of the motion, but no examples are known to have been produced until long after the introduction of the first widespread animation device: the phénakisticope.

Thaumatropes are often seen as important antecedents of motion pictures and in particular of animation. This is partly due to many film historians' belief that the associated theory of persistence of vision explains the physiological basis for movies, although this was disproved in 1912.

The coined name translates roughly as "wonder turner", from Ancient Greek: θαῦμα "wonder" and τρόπος "turn".

In 2012, it was reported that a prehistoric thaumatrope had been discovered in the Chauvet Caves in France, but it is very uncertain if this little disc was actually perceived as a thaumatrope when it was made.

The invention of the thaumatrope is usually credited to John Ayrton Paris. Paris was said to have used one to demonstrate persistence of vision to the Royal College of Physicians in London in 1824.Charles Babbage recalled in 1864 that the thaumatrope was invented by the geologist William Henry Fitton after he (Babbage) had told Fitton how the astronomer John Herschel had made him see two sides of a shilling at once by spinning it.

The first commercial thaumatrope was registered at Stationers' Hall on April 2, 1825 and published by W. Phillips in London as The Thaumatrope; being Rounds of Amusement or How to Please and Surprise By Turns, sold in boxes of 12 or 18 discs. It included a sheet with mottoes or riddles for each disc, often with a political meaning. Paris was widely regarded as the author, but wasn't mentioned on the product or its packaging and he later claimed in a letter to Michael Faraday "I was first induced to publish it, at the earnest desire of my late friend Wm Phillips. (...) I may add that I never put my name to it".

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Wikipedia