Sir John Herschel (1792-1871), British astronomer and chemist. John was the son of the great astronomer Sir William Herschel and was born at Slough. He was educated at Eton College and St.John's College, Oxford. He took up astronomy in 1816 and built his own telescope with which to re-examine the double stars his father had catalogued. In 1833 he set up an observatory at Cape Town, South Africa, where he mapped the southern skies and discovered that the Magellanic Clouds are composed of stars. On his return to England, he worked on the chemistry of photography, inventing the cyanotype process, coining the phrase 'photography' and being the first to use a solution of sodium thiosulphate (hypo) as a fixing agent. He was also the first person to produce a photograph on a glass plate and to apply photography to astronomy. Herschel was created a baronet in 1838.