# The New International Encyclopædia/Adams, John Couch

**ADAMS**, John Couch (1819-92). An English astronomer. He was born near Launceston, in Cornwall, and early manifested an aptitude for mathematics. After the usual amount of school training he was sent to St. John's College, Cambridge, where he attained the honor of senior wrangler, and became a mathematical tutor. In 1843 he attempted to ascertain by mathematical calculation whether certain observed irregularities in the motion of Uranus could be explained on the hypothesis of perturbation (q.v.) exercised by an exterior planet. The problem at issue was the inverse of the usual perturbation problem. Instead of computing the effect brought about by a planet of known mass pursuing a known orbit, it was required to determine the unknown cause of a known effect. By 1845 Adams had solved this new problem, and was able to assign to the hypothetical planet, the now well known Neptune, a position differing less than two degrees from its actual place in the sky. But a careful telescopic search was at the time postponed or neglected, so that the honor of the great discovery completing Adams's mathematical researches by an observational verification was lost to Great Britain. Leverrier, of Paris, had been making an independent investigation, and by August 31, 1846, he too had determined Neptune's place in the sky. He wrote to Galle at Berlin, and the latter found the planet on September 23 of the same year. This mathematical discovery of Neptune is justly counted among the greatest triumphs of science.