Herschel, John (Frederick William) (1792-1871)

English scientist, astronomer, and photographer who discovered thousands of close double stars, clusters, and nebulae. He coined the terms 'photography', 'negative', and 'positive', discovered sodium thiosulphite as a fixer of silver halides, and invented the cyanotype process; his inventions also include astronomical instruments. Herschel was born in Slough, the son of William Herschel, and studied at Cambridge. He held no academic post but devoted himself to private research. He mapped the southern skies from the Cape of Good Hope Observatory in South Africa 1834-38. During the early days of photography he gave lectures on the subject and exhibited his own images. Together with James South, he won the Gold Medal of the Astronomical Society 1826 for their catalogue of double stars published 1824. His works include Outlines of Astronomy 1849, which became a standard textbook; General Catalogue of Nebulae and Clusters, still the standard reference catalogue; and General Catalogue of 10,300 Multiple and Double Stars, published posthumously.