b. 1792 Slough, Great Britain, d. 1871 Collingwood, Great Britain
draftsman; photographer; scientist
Sir John Herschel was a scientist and astronomer like his father, Sir William Herschel. In 1809 he entered the University of Cambridge; in 1812 he submitted his first mathematical paper to the Royal Society, of which he was elected a fellow the following year. An accomplished chemist, Herschel discovered the action of hyposulfite of soda on otherwise insoluble silver salts in 1819, which led to the use of "hypo" as a fixing agent in photography. In 1839, independently of William Henry Fox Talbot, Herschel also invented a photographic process using sensitized paper. It was Herschel who coined the use of the terms photography , positive , and negative to refer to photographic images. In 1820 Herschel became a founding member of the Royal Astronomical Society. From 1833 until 1838, his astronomical investigations brought him and his family to the Cape of Good Hope in South Africa, where he met Julia Margaret Cameron, who became a lifelong friend. In 1850 Herschel was appointed master of the Mint, but he resigned six years later due to poor health. His remaining years were spent working on his catalogs of double stars and of nebulae and star clusters.