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ADAMS senior wrangler and first Smith’s prizeman of his year. question, prevailed even to the utmost bounds of the solar While still an undergraduate he happened to read of system. certain unexplained irregularities in the motion of the The honour of. knighthood was offered to Adams when planet Uranus, and determined to investigate them as soon Queen Victoria visited Cambridge next year; but then, as as. possible, with a view to ascertaining whether they on a subsequent occasion, his modesty led him to decline it. might not be due to the action of an undiscovered planet The Royal Society awarded him its Copley medal in 1848 beyond it. Elected fellow of his college in 1843, he at In the same year the members of St John’s College comonce proceeded to attack the novel problem. It was this : memorated his success by founding in the University an from the observed perturbations of a known planet to Adams prize, to be given biennially for the best treatise deduce by calculation, assuming only Newton’s law of on a mathematical subject. In 1851 he became president gravitation, the mass and orbit of an unknown disturbing of the Royal Astronomical Society. His lay fellowship at body. By September 1845 he obtained his first solution, St Johns College came to an end in 1852, and the existand handed to Professor Challis, the director of the ing statutes, did not permit of his re-election. Pembroke Cambridge Observatory, a paper giving the elements of College, which possessed greater freedom, elected him in what he described as “the new planet.” On 21st October the following year, to a lay fellowship, and this he held for 1845 he left at Greenwich Observatory, for the information the rest of his life. In 1858 he became professor of of Airy, the astronomer royal, a similar document, still mathematics at St Andrews, but lectured only for a preserved among the archives. A fortnight afterwards Airy wrote asking a question about a point in the solution. session, when he vacated the chair for the Lowndean professorship of astronomy and geometry at Cambridge. Adams, who thought the point trivial, did not reply, and Two years later he succeeded Challis as director of the Airy for some months took no steps to verify by telescopic Observatory, where he resided until his death. In 1863 search the results of the young mathematician’s investiga- he married Miss Eliza Bruce, of Dublin, who survived tion. Meanwhile, Le Yerrier, on 10th November 1845, him. presented to the French Academy a memoir on Uranus' Although Adams’s researches on Neptune were those showing that the existing theory failed to account for its which attracted widest notice, the work he subsequently motion. Unaware of Adams’s work, he attempted a like performed in relation to gravitational astronomy and inquiry, and on 1st June 1846, in a second memoir, gave terrestrial was not less remarkable. Several the position, but not the mass or orbit, of the disturbing of his mostmagnetism striking contributions to knowledge originated body whose existence was presumed. The longitude he m the discovery of errors or fallacies in the work of his assigned differed by only 1° from that predicted by Adams great predecessors in astronomy. Thus in 1852 he pubm the document which Airy possessed. The latter was lished new and accurate tables of the moon’s parallax struck by the coincidence, and mentioned it to the Board which superseded Burckhardt’s, and supplied corrections of Visitors of the Observatory, Challis and Herschel being to the theories of Damoiseau, Plana, and Pontecoulant present.. Herschel, at the ensuing meeting of the British In the following year his memoir on the secular acceleraAssociation early in September, accordingly ventured to tion of the moon’s mean motion disproved the validity of predict that a new planet would shortly be discovered Laplace’s famous explanation, which had held its place Meanwhile Airy had in July suggested to Challis that the unchallenged for sixty years. At first, Le Yerrier, Plana, planet should be sought for with the Cambridge equatorial. and others abroad disputed the soundness of Adams’s The search was begun by a laborious method at the end of the month. On 4th and 12th August, as afterwards startling result; but further inquiry established beyond question that he was right, and his memoir produced appeared, the planet was actually observed ; but owing to nothing less than a revolution in this branch of theoretical the want of a proper star-map it was not then recognized as astronomy.. The Royal Astronomical Society in 1866 planetary. Le Yerrier, still ignorant of these occurrences awarded him its gold medal for these researches. The presented on 31st August 1846 a third memoir, giving for the first time the mass and orbit of the new body. He great, meteor shower of 1866 turned his attention to the Leonids, whose probable path and period had already been communicated his results by letter to Dr Galle, of the discussed by Professor H. A- Newton. Using a powerful Berlin Observatory, who at once examined the suggested and elaborate analysis, Adams ascertained that this cluster region of the heavens. On 23rd September he detected of meteors, which belongs to the solar system, traverses near the predicted place a small star unrecorded in the a nearly circular orbit in 331 years, and is subject to map, and next evening found that it had a proper motion. No doubt remained that “ Le Verrier’s planet” had been definite perturbations from the larger planets, Jupiter, Saturn, and Uranus. These results were published in discovered. On the announcement of the fact Herschel 1867. Ten years later, when Mr G. W. Hill of Washington and Challis made known that Adams had already calculated the planet’s elements and position. Airy at length pub- brought out a new and beautiful method for dealing with lished an account of the circumstances, and Adams’s the problem of the lunar motions, Adams announced in a memoir was printed as an appendix to the Nautical brief notice his own work in the same field, which had Almanac. A keen controversy arose in France and followed a parallel course. His results confirmed and supplemented Hill’s. In 1874-76 he was president of the England as to the merits of the two astronomers. In the Royal Society for the second time, when it latter country much surprise was expressed at the apathy fell to Astronomical him to present the gold medal of the year to Le Verrier. The determination of the constants in Gauss’s t? i • *7 ’ 111 were ^rance the claims made for an the unknown Englishman resented as detracting from credit theory of terrestrial magnetism occupied him at intervals due to Le Yerner’s achievement. As the indisput- for over forty years. The calculations involved great able facts became known, the world recognized that labour, and were not published during his lifetime. They the two astronomers had independently solved the were edited by his brother, Professor W. Grylls Adams, problem of Uranus, and to each ascribed an equal glory. The new planet, at first called Le Verrier by and appear in the second volume of the collected Scientific Papers. Numerical computation of this kind might almost Arago, received by general consent the neutral name of be described as his pastime. The value of the constant Neptune. Its mathematical prediction was not only an known as Euler’s, and the Bernoullian numbers up to the unsurpassed intellectual feat; it showed also that Newton’s law of gravitation, which Airy had almost called in 62nd, he worked out to an unimagined degree of accuracy. For Newton and his writings he had a boundless admira-