1825, and a disputed inventor. The thaumatrope — Greek for 'wonder-turner' — was published in London in April 1825 by the physician John Ayrton Paris with the publisher W. Phillips, and Paris is usually credited with it. The attribution is not secure. Charles Babbage recalled in 1864 that the real inventor was the geologist William Henry Fitton, and gave a chain of events: the astronomer John Herschel asked Babbage how to see both faces of a shilling at once, then demonstrated the answer by spinning the coin on a table; Babbage repeated the story to Fitton, who days later produced a card disc suspended between two threads. The blueprint you have just built is Fitton's object, whoever's name ended up on the toy.

What it was sold as. Paris presented it as a demonstration of persistence of vision — the idea that an impression lingers in the eye for roughly an eighth of a second after the light stops. That is the explanation printed on nineteenth-century thaumatrope packaging and repeated in most histories of cinema.

Where that explanation stands now. Persistence of vision is a real retinal effect, but it is not a sufficient account of how alternating or moving images fuse. Modern vision science treats flicker fusion and apparent motion as separate mechanisms involving processing beyond the retina, and the old 'lingering image' story is specifically disputed as the cause of motion in film. The thaumatrope still works exactly as it always did; the textbook explanation attached to it for a century is the part that has been revised.

What came after. The phenakistiscope and zoetrope of the early 1830s added a sequence of images and a shutter, turning two alternating pictures into apparent movement. The thaumatrope is the first step of that line and the only one simple enough to make in half an hour.

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Kaleidoscope

Thaumatrope