Sir William's son, Sir John Frederick William Herschel, 1792–1871, first distinguished himself as a mathematician at Cambridge but later turned to astronomy. He confirmed his father's observations of double stars, was able to add numbers of previously unrecognized pairs to those in the catalog, and extended his examination to include nebulae. He presented his results to the Royal Society in the form of a catalog of stars in 1833. In order to complete the survey of the heavens, he went to the Cape of Good Hope in 1834 and discovered and measured many previously unseen nebulae and clusters of stars in the southern sky.
Among his books are Outlines of Astronomy (1849) and A General Catalogue of Nebulas (1864). The latter was revised by Johan Dreyer as A New General Catalogue of Nebulas and Clusters of Stars (1888), and, generally known as the NGC (see New General Catalog), it still serves as a standard reference source. Sir John also made contributions to the field of photography. He was the first to use sodium thiosulfate (hypo) as a fixing agent, and he introduced the terms "positive image" and "negative image."
See his diaries and correspondence, Herschel at the Cape, ed. by D. S. Evans et al. (1969); biography by G. Buttman (tr. 1970); J. F. Herschel and S. S. Silvan, Aspects of the Life and Thought of Sir John Frederick Herschel (1981); B. and N. Warner, Maclear and Herschel (1984).
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.