THE PLANET NEPTUNE. 23 



September, at Altona and Hamburg on the 28th, and 

 at London on the 30th. 



We must now return to Professor Challis, whom we 

 left exploring a large zone of the heavens, and re- 

 cording the exact position of every star down to the 

 eleventh magnitude. These observations were continued 

 from the 29th of July to the 29th of September, during 

 which time he had made more than three thousand 

 observations of stars. On the 29th of September, Pro- 

 fessor Challis saw for the first time Le Yerrier's memoir 

 communicated to the Academy August 31st. Struck 

 with the confidence which Le Yerrier manifested in his 

 own conclusions, Professor Challis immediately changed 

 his mode of observation, and endeavored to distinguish 

 the planet from the fixed stars by means of its disc. On 

 the same evening he swept over the zone marked out 

 by Le Yerrier, paying particular attention to the phys- 

 ical appearance of the brighter stars. Out of three hun- 

 dred stars, whose positions were recorded that night, he 

 selected one which appeared to have a disc, and which 

 proved to be the planet. On the first of October he 

 heard of the discovery at Berlin ; and now, on comparing 

 his numerous observations, he finds that he had twice 

 observed the planet before, viz., on August 4th and 

 12th ; but he lost the opportunity of being first to an- 

 nounce the discovery, by deferring too long the discus- 

 sion of his observations. 



The news of this capital discovery was brought to this 

 country by the steamer of October 4th, and every tele- 



