JOHN COUCH ADAMS. 445 



himself to his favorite mathematical pursuits, and in 1858 he was made 

 Professor of Mathematics at the University of St.Audrews in Scotland. 

 He held this position only for a year, as in 1859 he was appointed to 

 a Cambridge Professorship, and accordingly returned to his former 

 residence. In 1861 he succeeded Professor Challis as Director of the 

 Cambridge Observatory, and continued in that office until his death, 

 on January 21, 1892, after a protracted illness. In 1881 , he was offered 

 the position of Astronomer Royal, left vacant by Airy's retirement; 

 but advancing years made him unwilling to accept a place requiring 

 so much exertion from its occupant. 



The life of Adams, thus outwardly uneventful, practically consisted 

 of a series of mathematical researches. It may be said to have opened 

 with one which had the quality, rare in such work, of attracting public 

 attention by its dramatic character. Immediately after his graduation, 

 he directed his thoughts to the subject, then ripe for consideration, of 

 the unexplained irregularities in the movements of Uranus, and to the 

 question whether the place of an unknown planet, capable of producing 

 such perturbations, could be defined by calculation. In 1845 his 

 solution of the problem was communicated to Challis and to Airy, 

 the Directors of the Cambridge and Greenwich Observatories ; but 

 partly through accident, partly through the adoption of* too mechanical 

 methods in such search as was undertaken for the theoretical planet 

 in England, the discovery of the actual planet Neptune was reserved 

 for the continent of Europe, where Leverrier furnished the prediction 

 verified by Galle. The similarity of the results independently attained 

 by Adams and by Leverrier was such as to exclude, at least to the 

 uninstructed mind, the possibility that either of the investigators could 

 have erred in his method of inquiry ; and the remarkable nature of 

 their achievement won for them general admiration and applause. 

 The theoretical planet which they had discovered by inference certainly 

 differed in many important respects from the observed planet found 

 by Galle. Whether the approximate coincidence of the apparent 

 place among the stars occupied in 1846 by the theoretical and real 

 objects was casual or not, this certainly formed a question to be 

 considered only by men who felt themselves able to compete mathe- 

 matically with Adams ; and it has never been minutely considered by a 

 sufficient number of such men to establish a decision upon the subject 

 from which no appeal can be taken. But in the absence of a clear 

 decision to the contrary, the scientific world continues to regard the 

 predictions of Adams and Leverrier as a real mathematical discovery .; 

 while in any case there can be no doubt of the evidence of mental 



