1911 Encyclopædia Britannica/Adams, John Couch

ADAMS, JOHN COUCH (1819–1892), British astronomer, was born at Lidcot farmhouse, Laneast, Cornwall, on the 5th of June 1819. His father, Thomas Adams, was a tenant farmer; his mother, Tabitha Knill Grylls, inherited a small estate at Badharlick. From the village school at Laneast he went, at the age of twelve, to Devonport, where his mother’s cousin, the Rev. John Couch Grylls, kept a private school. His promise as a mathematician induced his parents to send him to the university of Cambridge, and in October 1839 he entered as a sizar at St John’s College. He graduated B.A. in 1843 as the senior wrangler and first Smith’s prizeman of his year. While still an undergraduate he happened to read of certain unexplained irregularities in the motion of the planet Uranus, and determined to investigate them as soon as possible, with a view to ascertaining whether they might not be due to the action of a remote undiscovered planet. Elected fellow of his college in 1843, he at once proceeded to attack the novel problem. It was this: from the observed perturbations of a known planet to deduce by calculation, assuming only Newton’s law of gravitation, the mass and orbit of an unknown disturbing body. By September 1845 he obtained his first solution, and handed to Professor Challis, the director of the Cambridge Observatory, a paper giving the elements of what he described as “the new planet”.

On the 21st of October 1845 he left at Greenwich Observatory, for the information of Sir George Airy, the astronomer-royal, a similar document, still preserved among the archives. A fortnight afterwards Airy wrote asking for information about a point in the solution. Adams, who thought the query unessential, did not reply, and Airy for some months took no steps to verify by telescopic search the results of the young mathematician’s investigation. Meanwhile, Leverrier, on the 10th of November 1845, presented to the French Academy a memoir on Uranus, showing that the existing theory failed to account for its motion. Unaware of Adams’s work, he attempted a like inquiry, and on the 1st of June 1846, in a second memoir, gave the position, but not the mass or orbit, of the disturbing body whose existence was presumed. The longitude he assigned differed by only 1° from that predicted by Adams in the document which Airy possessed. The latter was struck by the coincidence, and mentioned it to the Board of Visitors of the Observatory, James Challis and Sir John Herschel being present. Herschel, at the ensuing meeting of the British Association early in September, ventured accordingly to predict that a new planet would shortly be discovered. Meanwhile Airy had in July suggested to Challis that the planet should be sought for with the Cambridge equatorial. The search was begun by a laborious method at the end of the month. On the 4th and 12th of August, as afterwards appeared, the planet was actually observed; but owing to the want of a proper star-map it was not then recognized as planetary. Leverrier, still ignorant of these occurrences, presented on the 31st of August 1846 a third memoir, giving for the first time the mass and orbit of the new body. He communicated his results by letter to Dr Galle, of the Berlin Observatory, who at once examined the suggested region of the heavens. On the 23rd of September he detected near the predicted place a small star unrecorded in the map, and next evening found that it had a proper motion. No doubt remained that “Leverrier’s planet” had been discovered. On the announcement of the fact, Herschel and Challis made known that Adams had already calculated the planet’s elements and position. Airy then at length published an account of the circumstances, and Adams’s memoir was printed as an appendix to the Nautical Almanac. A keen controversy arose in France and England as to the merits of the two astronomers. In the latter country much surprise was expressed at the apathy of Airy; in France the claims made for an unknown Englishman were resented as detracting from the credit due to Leverrier’s achievement. As the indisputable facts became known, the world recognized that the two astronomers had independently solved the problem of Uranus, and ascribed to each equal glory. The new planet, at first called Leverrier by F. Arago, received by general consent the neutral name of Neptune. Its mathematical prediction was not only an unsurpassed intellectual feat; it showed also that Newton’s law of gravitation, which Airy had almost called in question, prevailed even to the utmost bounds of the solar system.

The honour of knighthood was offered to Adams when Queen Victoria visited Cambridge in 1847; but then, as on a subsequent occasion, his modesty led him to decline it. The Royal Society awarded him its Copley medal in 1848. In the same year the members of St John’s College commemorated his success by founding in the university an Adams prize, to be given biennially for the best treatise on a mathematical subject. In 1851 he became president of the Royal Astronomical Society. His lay fellowship at St John’s College came to an end in 1852, and the existing statutes did not permit of his re-election. But Pembroke College, which possessed greater freedom, elected him in the following year to a lay fellowship, and this he held for the rest of his life. In 1858 he became professor of mathematics at St Andrews, but lectured only for a session, when he vacated the chair for the Lowndean professorship of astronomy and geometry at Cambridge. Two years later he succeeded Challis as director of the Observatory, where he resided until his death.

Although Adams’s researches on Neptune were those which attracted widest notice, the work he subsequently performed in relation to gravitational astronomy and terrestrial magnetism was not less remarkable. Several of his most striking contributions to knowledge originated in the discovery of errors or fallacies in the work of his great predecessors in astronomy. Thus in 1852 he published new and accurate tables of the moon’s parallax, which superseded J. K. Burckhardt’s, and supplied corrections to the theories of M. C. T. Damoiseau, G. A. A. Plana and P. G. D. de Pontécoulant. In the following year his memoir on the secular acceleration of the moon’s mean motion partially invalidated Laplace’s famous explanation, which had held its place unchallenged for sixty years. At first, Leverrier, Plana and other foreign astronomers controverted Adams’s result; but its soundness was ultimately established, and its fundamental importance to this branch of celestial theory has only developed further with time. For these researches the Royal Astronomical Society awarded him its gold medal in 1866. The great meteor shower of 1866 turned his attention to the Leonids, whose probable path and period had already been discussed by Professor H. A. Newton. Using a powerful and elaborate analysis, Adams ascertained that this cluster of meteors, which belongs to the solar system, traverses an elongated ellipse in 331/4 years, and is subject to definite perturbations from the larger planets, Jupiter, Saturn and Uranus. These results were published in 1867. Ten years later, when Mr. G. W. Hill of Washington expounded a new and beautiful method for dealing with the problem of the lunar motions, Adams briefly announced his own unpublished work in the same field, which, following a parallel course had confirmed and supplemented Hill’s. In 1874–1876 he was president of the Royal Astronomical Society for the second time, when it fell to him to present the gold medal of the year to Leverrier. The determination of the constants in Gauss’s theory of terrestrial magnetism occupied him at intervals for over forty years. The calculations involved great labour, and were not published during his lifetime. They were edited by his brother, Professor W. Grylls Adams, and appear in the second volume of the collected Scientific Papers. Numerical computation of this kind might almost be described as his pastime. The value of the constant known as Euler’s, and the Bernoullian numbers up to the 62nd, he worked out to an unimagined degree of accuracy. For Newton and his writings he had a boundless admiration; many of his papers, indeed, bear the cast of Newton’s thought. He laboured for many years at the task of arranging and cataloguing the great collection of Newton’s unpublished mathematical writings, presented in 1872 to the university by Lord Portsmouth, and wrote the account of them issued in a volume by the University Press in 1888. The post of astronomer-royal was offered him in 1881, but he preferred to pursue his peaceful course of teaching and research in Cambridge. He was British delegate to the International Prime Meridian Conference at Washington in 1884, when he also attended the meetings of the British Association at Montreal and of the American Association at Philadelphia. Five years later his health gave way, and after a long illness he died at the Cambridge Observatory on the 21st of January 1892, and was buried in St Giles’s cemetery, near his home. He married in 1863 Miss Eliza Bruce, of Dublin, who survived him. An international committee was formed for the purpose of erecting a monument to his memory in Westminster Abbey; and there, in May 1895, a portrait medallion, by Albert Bruce Joy, was placed near the grave of Newton, and adjoining the memorials of Darwin and of Joule. His bust, by the same sculptor, stands opposite that of Sir John Herschel in the hall of St John’s College, Cambridge. Herkomer’s portrait is in Pembroke College; and Mogford’s, painted in 1851, is in the combination room of St John’s. Another bust, taken in his youth, belongs to the Royal Astronomical Society. A memorial tablet, with an inscription by Archbishop Benson, is placed in the Cathedral at Truro; and Mr Passmore Edwards erected a public institute in his honour at Launceston, near his birthplace.

The Scientific Papers of John Couch Adams, 4to, vol. i. (1896), and vol. ii. (1900), edited by William Grylls Adams and Ralph Allen Sampson, with a memoir by Dr J. W. L. Glaisher, were published by the Cambridge University Press. The first volume contains his previously published writings; the second those left in manuscript, including the substance of his lectures on the Lunar Theory. A collection, virtually complete, of Adams’s papers regarding the discovery of Neptune was presented by Mrs Adams to the library of St John’s College. A description of them by Professor Sampson was inserted in the Memoirs of the Royal Astronomical Society (vol. liv. p. 143). Consult: Month. Notices Roy. Astr. Soc., liii. 184; Observatory, xv. 174; Nature, xxxiv. 565, xlv. 301; Astr. Journal, No. 254; R. Grant, Hist. of Physical Astronomy, p. 168; Edinburgh Review, No. 381, p. 72.