John Frederick William Herschel (1792-1871), British astronomer. John Herschel continued the work of his father, William Herschel, through studying nebulae (galaxies) and double stars. He set up an observatory in South Africa that mapped the southern skies, where he found that the Magellanic Clouds are composed of stars. Herschel returned to England in 1838, where he was awarded a Baronetcy. He worked on the chemistry of photography, where he was the first to use sodium thiosulphate solution (hyposulphite of soda, or hypo) as a permanent photographic fixing agent. He was also a pioneer in using glass plates and coined the photographic terms 'negative' and 'positive'. At his death, aged 79, he was given a national funeral and buried in Westminster Abbey. Photographed by Julia Margaret Cameron in 1861.