Optical toys and inventions – a precursor to the moving image and cinema A thaumatrope is a disk with a different but related picture on each side that 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. The retina of your eye sends visual information back to your brain. The nerve pulses from the eye to brain are not instantaneous. An image produced by the retina in response to stimulation lingers for one-tenth to one- twentieth of a second. Physiologists call this the principle of the persistence of vision. The thaumatrope fools your eye by switching images faster than the tenth-of-a-second limit, thus merging what are in fact two separate images into one visual impression. From 1833 the same principle was used in the Phenakistiscope where slightly different images of the same object were drawn around the edge of a disc, when the disc was spun and the images viewed through a slot in the cover, the images gave the impression of movement. But as there were multiple images a sequence of movement was created. Then in 1866 this was developed into the Zoetrope where the pictures were placed on a horizontal cylinder and viewed through slots on the cylinder itself. This allowed for even more images to be used in the moving sequence and more than one person could view it at once. There was a development of this by Eadweard Muybridge (Edward James Muggeridge) in 1878. He set up a series of 24 cameras and ran a horse in front of them and then played those images as photographic flipcards to show how it ran. But this soon developed into a version of the zoetrope which he called the Zoopraxiscope. This was the first time that there was conclusive evidence that, when galloping, a horse always kept one hoof on the ground. This was the first ever cinematic film shot and shown to audiences. Then in 1894 the Mutoscope came in with hundreds of sequential photographs on a rotating core, allowing a minute of moving pictures. These continued on into the 1950’s as amusement arcade machines. But by the 1890s proper cine cameras had been introduced and individual photographs no longer had to be spliced together and movies had been invented. Now of course replaced by magnetic tapes, cd discs and computer chip storage. But they all rely on your nervous system from the eye to brain having a built-in delay! .