294 NINETEENTH CENTURY. rx. rn. 



in his path ; and wherever the planet did not follow their 

 pulling he had to calculate where another body must be to 

 draw it away from them. This he accomplished, and it is 

 very remarkable that the great living French astronomer 

 named Leverrier also worked out the same problem, without 

 having heard that Adams had done it. 



In the year 1839 Leverrier had begun a long series of 

 calculations (which were only completed last year, 1874), to 

 find out the varying attractions, and by that means the size 

 and weight, of the different planets, and while he was at 

 work at this he became convinced that there must be some 

 unseen body pulling at Uranus. Now it so happened that 

 just at the time when Adams and Leverrier began to feel 

 after this supposed planet, Uranus had lately been very much 

 disturbed, and so they knew that the disturbing cause must 

 have approached near to him, and this showed them in 

 which part of the heavens the attracting planet ought to be. 



Leverrier published his calculations in the Journal of 

 the Academie des Sciences at Paris for June 1846, and when 

 the Astronomer- Royal read the paper he was astonished to 

 find that the French astronomer had fixed the place of the 

 unknown planet within one degree of the spot which Adams 

 had named. This led him to read Adams's paper again 

 more carefully, and to put the two astronomers into com- 

 munication with each other ; and the consequence was that 

 Leverrier wrote another paper in August 1846, stating still 

 more accurately where the planet ought to be found. This 

 paper he sent to his friend M. Galle, of the Berlin Obser- 

 vatory, on September 23, 1846, asking him to look for 

 the planet in that part of the sky which he pointed out. M. 

 Galle did so, and on that same nighty by following the instritc- 

 tions of the two astronomers^ he found the unknown planet. 



