ADAMS, JOHN COUCH (IST9-18921, British astronomer, was horn at Lidcot farmhouse, Laneast, Cornwall, on June 5, 1819. He was educated at St. John's College, Cambridge, and was senior wrangler and first Smith's prizeman of his year, While still an undergraduate he read of certain unexplained irreg ularities in the motion of the planet Uranus and determined to investigate them, with a view to ascertaining whether they might not he due to the action of a remote undiscovered planet. Elected fellow of his college in 1343, he at once attacked the problem. It was this : from the observed perturbations of a known planet to deduce by calculation, assuming only Newton's law of gravi tation, the mass and orbit of an unknown disturbing body. By Sept. 1845 he obtained his first solution, and handed to Prof. Challis, the director of the Cambridge Observatory, a paper giv ing the elements of what he described as "the new planet." It was not until July 1846 that the search for the new planet was begun at Cambridge. Meanwhile the French astronomer Leverrier had been working along similar lines with equally suc cessful results, and a controversy arose as to whether the dis covery of the new planet, Neptune, should be ascribed to the English or the French astronomer. As the facts became known the world recognized that the two astronomers had independently solved the problem of Uranus. The new planet, at first called Leverrier by F. Arago, received by general consent the neutral name of Neptune. Its mathematical prediction was an unsur passed intellectual feat.
In 1851 Adams became president of the Royal Astronomical Society. His lay fellowship of St. John's College came to an end in 1852, but Pembroke College elected him in the following year to a lay fellowship which 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 at tracted widest notice, his subsequent work on gravitational as tronomy and terrestrial magnetism was not less remarkable. In 1852 he published new and accurate tables of the moon's parallax, which superseded J. K. Burckhardt's, and supplied corrections to the theories of M. C. T. Damoiseau, G. A. A. Plana and P. G. D. de Pontecoulant. 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 unchal lenged for 6o years. 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 prob able path and period had already been discussed by Prof. H. A. Newton. Adams ascertained that this cluster of meteors, which belongs to the solar system, traverses an elongated ellipse in 33 years and three months, and is subject to definite perturbations from the larger planets, Jupiter, Saturn and Uranus. These re sults were published in 1867. Ten years later, when G. W. Hill of Washington expounded a new method for dealing with the prob lem of the lunar motions, Adams briefly announced his own un published work in the same field, which, following a parallel course, had confirmed and supplemented Hill's.