The Outer Planets 253 



Adams, each independently of the other, calculated the 

 position of the unseen body which was influencing the 

 motion of Uranus, and advised that it be looked for in 

 this place. Few persons have ever solved so difficult 

 a problem as this calculation involved. If you are 

 pleased when you succeed in understanding something 

 which for a time seemed beyond your power of com- 

 prehension, you can appreciate the feelings of these 

 astronomers who, after working faithfully on a problem 

 that seemed almost impossible of solution, could say: 

 " Point your telescope in a certain direction [which 

 they definitely specified] and you will see a world here- 

 tofore unknown." 



