# Dictionary of National Biography, 1885-1900/Main, Robert

​MAIN, ROBERT (1808–1878), astronomer, brother of Thomas John Main [q. v.], was born at Upnor in Kent on 12 July 1808. He was educated at Portsea, became assistant-master in the grammar school at Bishop's Waltham, Hampshire, and saved out of his stipend funds for a university career. Having obtained a foundation scholarship in Queens' College, Cambridge, he graduated as sixth wrangler in 1834, was elected to a fellowship, took orders, and proceeded M.A. in 1837. In 1835 he was appointed chief assistant at the Royal Observatory under Sir George Airy, with whom he admirably co-operated during twenty-five years. He found time, moreover, to apply the results obtained to the elucidation of points of interest, and the correction of the fundamental constants of astronomy. On 9 June 1837 he presented to the Royal Astronomical Society the first of a series of papers on the ‘Elements of the Planet Venus’ (Memoirs, x. 295, xi. 139, 159), and on 8 May 1840 a critical and historical essay ‘On the Present State of our Knowledge of the Parallax of the Fixed Stars’ (ib. xii. 1). He established in 1849, from his own micrometrical measures, the elliptical symmetry of Saturn's figure (ib. xviii. 27), and in 1855 the unvarying dimensions of his rings (ib. xxv. 1). In 1850 and 1858 he deduced the proper motions of 1,440 stars common to Bessel's ‘Fundamenta’ and the Greenwich catalogues (ib. xix. 121, xxviii. 127); investigated in 1855 and 1860 the constants of aberration and notation, and the annual parallax of γ Draconis (ib. xxiv. 147, xxix. 169); tested the accuracy of Bessel's table of refractions (ib. xxvi. 45), and communicated in 1856 the results of twelve years' determinations of the planetary diameters with Airy's double-image micrometer (ib. xxv. 21). These important works were distinguished in February 1858 with the gold medal of the Astronomical Society. The address was delivered by Manuel John Johnson [q. v.] (Monthly Notices, xviii. 123). Main's membership of that body dated from 1836; he served for thirty-nine years on the council, and acted successively as its secretary and president. He was elected a fellow of the Royal Society in 1860.
Main succeeded Johnson as Radcliffe observer on 19 June 1860, and resided at Oxford from 1 Oct. 1860. The efficiency of the establishment was fully maintained by him. He edited in December 1860 the first Radcliffe catalogue, compiled the second Radcliffe catalogue of 2,386 stars (Oxford, 1870), from observations made 1854–61, and began, with the Redhill transit-circle, purchased from Richard Christopher Carrington [q. v.] in 1861, a new series designed to furnish materials for a third catalogue, which, however, he did not live to complete. Sixteen volumes of ‘Radcliffe Observations,’ successively issued by him, included a valuable series of double-star measures with the heliometer; and he presented to the Royal Astronomical Society observations of Jupiter's satellites, of the great comet of 1861 (ib. xxi. 210, xxii. 50), and of the dimensions of the disc of Mars during the opposition of 1862 (Memoirs Astronomical Society, xxxii. 97), made with the same instrument. His record of the meteoric shower of 13 Nov. 1866 was inserted in the ‘Monthly Notices,’ xxvii. 39.
He wrote for Weale's series in 1852 ‘Rudimentary Astronomy,’ prefixing to the second edition in 1869 a chapter on spectrum analysis. A third edition, revised by Mr. W. T. Lynn, appeared in 1882. Main published in 1860 a translation of the first part of Brünnow's ‘Sphärische Astronomie,’ and at Cambridge in 1863, with the assistance of his son, Mr. P. T. Main, ‘Practical and Spherical Astronomy,’ adapted for the use of university students. ‘Twelve Sermons’ preached by him in St. Mary's Church, Greenwich, were published in 1860, and he preached before the British Association at Bristol in 1875. An address on ‘Modern Philosophic Scepticism,’ read by him at the ninth annual meeting of the Victoria Institute, was frequently reprinted. He contributed to Weale's ‘London in 1851’ a chapter on observatories, and re-edited in 1859 Herschel's ‘Manual of Scientific Enquiry.’ Main married in 1838 a sister of Professor Kelland of Edinburgh, and left three sons. He died at the Rad​cliffe Observatory, after a short illness, on 9 May 1878. Besides being a fair classical scholar, he read fluently nine modern languages.
[Monthly Notices, xxxix. 227; Dunkin's Obit. Notices, p. 165; Observatory, ii. 55 (Pritchard); Nature, xviii. 72; Grant's Hist. of Astronomy, pp. 266, 557; André et Rayet's l'Astronomie Pratique, i. 60; Times, 13 May 1878; Athenæum, 18 May 1878; The National Church, vii. 123; Royal Society's Cat. Scientific Papers, vols. iv. viii.]
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