John Ayrton Paris (1785-1856), British physician. Paris was born in Cambridge and was educated there as well as in London and Edinburgh. In 1813 he finally obtained his MD as started practice as a physician. When working in Cornwall he was the first to observe an occupational cause of cancer - men working in copper smelting due to exposure to arsenic fumes. He was the first to demonstrate persistence of vision by inventing the thaumatrope. This is a disc of card on which different images are printed on each side. When the disc is spun, the images appear to merge. In 1844 he was elected president of the Royal College of Physicians. His books include works on medical jurisprudence and the Pharmacologia of 1820.