ASTRONOMY AND COSMIC THEORIES. 95 



a certain part of the heavens, and he sent his paper on 

 the subject to the Astronomer-Royal in October, 1845. 

 By an extraordinary coincidence, a French astronomer 

 (Leverrier) had been for some years working out the 

 motions of the various planets, and in doing so had also 

 reached the conclusion that there must be another un- 

 known body to produce the perturbations of Uranus, 

 which were at that time unusually large. His calcula- 

 tions and results were publishec^at Paris in November, 

 1845, and June, 1846, and he gave a position for the 

 unknown planet differing only one degree from that 

 given by Adams. On reading these papers, and seeing 

 the agreement of two independent workers, the Astrono- 

 mer-Royal asked Professor Challis, of the Cambridge 

 Observafory, to search for the planet, and on doing so he 

 actually observed it on August 4th, and again on August 

 12th; but having no accurate chart of that part of the 

 heavens he could not be sure that it was not a small star. 

 A month later it was found and identified at Berlin, from 

 information furnished by Leverrier. It thus appears 

 that Adams first privately announced the position of the 

 new planet, and that it was first observed at Cambridge ; 

 while the somewhat later announcement by Leverrier 

 and discovery at Berlin were made public, and thus 

 gained the honors of priority. The two discoveries 

 were, however, practically simultaneous and independ- 

 ent, and the names of Adams and Leverrier should for 

 ever be jointly associated with the planet Neptune. 



Other important discoveries in the planetary system 

 are due to the increased power of modern telescopes and 

 the greater number of observers. In 1877 two minute 

 satellites of Mars were discovered at Washington, by 



