SKETCH OF JOHN COUCH ADAMS. 547 



that part of the zone in the immediate neighborhood of the place 

 indicated by theory. Unfortunately, the observations were not 

 immediately compared with each other, or Prof. Challis would 

 have discovered, what he afterward found to be the case, that he 

 had actually seen the planet on August 4th and August 12th, the 

 third and fourth nights of observation. ... On September 3, 1846, 

 Adams communicated to the astronomer royal a new solution of 

 the problem, supposing the mean distance of the planet as origi- 

 nally assumed, to be diminished by about the thirtieth part. The 

 result of this change was to produce a better agreement between 

 the theory and the later observations, and to give a smaller and 

 therefore a more probable value of the eccentricity." 



Leverrier's first paper relative to the subject was presented to 

 the French Academy on November 10, 1845, and concerned the 

 perturbations of Uranus produced by Jupiter and Saturn ; but in 

 it he also pointed to irregularities which could not be accounted 

 for by the existing theory. In his second paper, June 1, 1846, he 

 expressed the conclusion that the unexplained irregularities were 

 due to an undiscovered planet exterior to Uranus. He calculated 

 the longitude, but did not give the elements of the orbit of the 

 disturbing planet. The place assigned by him to the supposed 

 body differed by only one degree from that given by Adams in 

 the paper which he had left at the Greenwich Observatory seven 

 months earlier. 



"Adams's researches," says Prof. Glaisher, " therefore preceded 

 Leverrier's by a considerable interval ; and in spite of the delay in 

 carrying out the search, it had been carried on at Cambridge 

 for nearly two months before the planet was found at Berlin. 

 Adams's investigation may be regarded as having been completed 

 on October 21, 1845, when he left his paper at the Royal Observa- 

 tory. This was three weeks before Leverrier's memoir, showing 

 that the irregularities could not be attributed to any of the known 

 planets, was presented to the French Academy, and more than 

 seven months before the presentation of Leverrier's second mem- 

 oir. It is to be noticed that in this second memoir Leverrier did 

 not give the elements of the orbit or the mass of the planet, which 

 were contained in Adams's paper of October 21st." 



A bitter controversy ensued over the question of priority in 

 discovery, in which Mr. Adams took no part. He felt and ex- 

 pressed a warm appreciation for Leverrier ; met him with great 

 pleasure at Oxford in 1847 ; and was visited by him in the same 

 year at Cambridge. A story was told of him for the first time by 

 Dr. Donald MacAlister at the commemorative meeting at St. 

 John's College, February 20, 1892, to the effect that several years 

 ago, when a memorial volume was prepared to be presented to M. 

 Pasteur as a testimonial of the appreciation of English men of 



