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GROOMBRIDGE, STEPHEN (1755–1832), astronomer, was born at Goudhurst in Kent on 7 Jan. 1755. He succeeded when about twenty-one to the business in West Smithfield of a linendraper named Greenland, to whom he had been apprenticed. Afterwards, and until 1816, he was a successful West India merchant. He resided chiefly at Goudhurst, where he built a small observatory; but his early love of astronomy was more fully gratified after his removal to Blackheath in 1802. On acquiring in 1806 a fine transit circle by Troughton (described in Pearson's 'Practical Astronomy,' ii. 402, and in Rees's 'Cyclopædia.' art. 'Circle'), he undertook the construction of a catalogue of stars down to 8·9 magnitude within fifty degrees of the pole. The results of upward of one thousand preliminary observations on atmospheric refraction were laid before the Royal Society on 28 March 1810, and a further series on 31 March 1814 (Phil. Trans. c. 190, civ. 337). After 1806 he devoted himself with such energy to his principal task that in ten years he accumulated some fifty thousand observations, all made by himself. His observatory opened off his dining-room, and he often rose from table to observe. He had corrected the whole for instrumental errors, and derived the mean places of about half the recorded stars, when a severe attack of paralysis disabled him in 1827 from further exertions. Sir George Airy says that, considering the circumstances, 'the work is one of the greatest which the long-deferred leisure of a private individual has ever produced.' The disturbed state of Europe caused it to be almost isolated.

On his partial recovery Groombridge applied, with success, to the board of longitude for assistance in completing his catalogue, which was prepared for press by Mr. Henry Taylor, and printed in 1832. This was suppressed, on the advice of Baily and Airy, on account of errors. Revised and corrected under Airy's supervision, the work eventually appeared in 1838, at the public expense, as 'A Catalogue of Circumpolar Stars, deduced from the Observations of Stephen Groombridge, F.R.S., reduced to Jan. 1, 1810.' It includes 4,243 star-places of standard accuracy, among them that of the swiftest-moving of known stars (No. 1830), first observed by Groombridge. The 'Catalogue,' Professor R. Grant remarks (Hist. Phys. Astronomy, p. 511), is 'universally admitted to be one of the most valuable contributions to practical astronomy made during the nineteenth century.' Groombridge retired from business in 1815, and devoted the leisure spared from astronomy to music, of which he was passionately fond. He was one of the founders of the Astronomical Society, sat on its first council, and took an active part in its proceedings. He was elected a fellow of the Royal Society in 1812, and was a member of the academy of Naples. The partial and annular eclipses of the sun of 19 Nov. 1816 and 7 Sept. 1820 respectively were observed by him (Phil. Mag. xlviii. 371 ; Mem. R. Astr. Soc. i. 135).

He died at Blackheath on 30 March 1832, and was buried at Goudhurst, leaving a reputation for integrity and kindness. He had high qualities as an observer, but was ignorant of the higher mathematics. His widow survived him only five months. Their only child, a daughter, married the Rev. Newton Smart of Farley Hospital, near Salisbury, and died before her parents, leaving one son. Groombridge's manuscripts were deposited, by his own request, with the Royal Astronomical Society. To the first two volumes of their 'Memoirs' he contributed, in November 1820, Universal Tables for the Reduction of the Fixed Stars,' in 1822 'Observations of the Planets,' in 1826 papers ' On the Colatitude of the Observatory at Blackheath,' and on the 'Horizontal Error of a Transit-Instrument.' He communicated on 16 Nov. 1812 to the Royal Society of Edinburgh a 'Comparison of the North Polar Distances of 38 Principal Fixed Stars as determined at Greenwich, Armagh, Palermo, Westbury, Dublin, and Blackheath' (Edinb. Phil. Trans. vii. 279); and his planetary observations, 1807-23, especially valuable for the theory of the minor planets, were inserted in supplements to the 'Berlin Ephemeris' for the corresponding years. He also wrote on astronomical subjects in the 'Philosophical Magazine' and the 'Quarterly Journal of Science.'

[Monthly Notices R. Astr. Society, ii. 145; Airy's Pref. to Groombridge's Catalogue ; Gent. Mag. 1832, pt. i. p. 379; Mädler's Geschichte der Himmelskunde, ii. 366.]

A. M. C.