188 THE HISTORY OF SCIENCE 



observations." Two years later he undertook re- 

 searches in reference to the new planet of whose ex- 

 istence he felt certain. His labors, however, were 

 interrupted by the death of his assistant Flemming, 

 and by his own illness, which proved fatal in 1846, 

 a few months before the actual discovery of Nep- 

 tune. It is evident that the quest of the new planet 

 had become general. The error of Uranus still 

 amounted to less than two minutes. This deviation 

 from the computed place is not appreciable by the 

 naked eye, yet it was felt, by the scientific world, to 

 challenge the validity of the Newtonian theory, or 

 to foreshadow the addition of still another planet to 

 our solar system. 



In July, 1841, John Couch Adams, a young under- 

 graduate of St. John's College, Cambridge, whose 

 interest had been aroused by reading Airy's paper 

 on the Progress of Astronomy, made note of his 

 resolution to attempt, after completing his college 

 course, the solution of the problem then forming in 

 so many minds. After achieving the B.A. as senior 

 wrangler at the beginning of 1843, Adams under- 

 took to " find the most probable orbit and mass of 

 the disturbing body which has acted on Uranus." 

 The ordinary problem in planetary perturbations 

 calls for the determination of the effect on a known 

 orbit exerted by a body of known mass and motion. 

 This was an inverse problem ; the perturbation being 

 given, it was required to find the position, mass, and 

 orbit of the disturbing planet. The data were fur- 

 ther equivocal in that the elements of the given 

 planet Uranus were themselves in doubt ; the unre- 

 liability of its planetary tables, in fact, being the 



