'Sir J F W Herschel', 1867.
© NMeM / Royal Photographic Society / Science & Society Picture Library
Photograph by Julia Margaret Cameron (1815-1879) of scientist and astronomer John Frederick William Herschel (1792-1871). Herschel was awarded numerous honours for his work in astronomy. He was also interested in photography; he was the first to use the word 'photography', and applied the terms 'positive' and 'negative' to the subject. He discovered that hyposulphate quickened the development of photographs, and invented the blueprint (or cyanotype) process. Cameron's portraits are considered among the best in early photography.