HERSCHEL, Sir John Frederick William b. 7 March 1792; d. 11 May 1871 The only son of the
book on the subject.
distinguished British astronomer William Herschel, Sir John himself also became a wellknown astronomer, and published an influential
He became interested in capturing and retaining images, and in 1839 had managed to fix pictures using hyposulphite of soda. In fact it was he who had discovered twenty years previously that hypo could dissolve silver salts. Herschel, of course, had the fortune to be around just at the time both Daguerre and Fox Talbot were announcing their discoveries. He was evidently very smitten by the Daguerreotype, and conveyed the following news to Fox Talbot: "It is hardly too much to call them miraculous. Certainly they surpass anything I could have conceived as within the bounds of reasonable expectation.... Every gradation of light and shade is given with a softness and fidelity which sets all painting at an immeasurable distance.... If you have a few days at your disposition....come and see!" Fox Talbot, for his part, would not have been very happy about this news, as he was already upset that Daguerre had pipped him to the post in announcing his discovery! It is also to Herschel that we also owe the word "photography", a term which he used in a paper entitled "Note on the art of Photography, or The Application of the Chemical Rays of Light to the Purpose of Pictorial Representation," presented to the Royal Society on 14 March 1839. He also coined the terms "negative" and positive" in this context, and also the "snap-shot". The picture of Heschel, on the left, was taken by J M Cameron, and on the right is the very first photograph to be taken on glass. It was taken by Sir John Herschel in 1839, and shows his father's telescope in Slough, near London. (Science Museum, London).