

ON THE SATELLITES OF URANUS. 101 



and that but in a single instance. This satellite he con- 

 sidered to be the most remote "of the six enumerated by 

 Herschel. 



With the exception, therefore, of the solitary observa- 

 tion of Dr. Lament, the only evidence we have had (until 

 recently) of the existence of more than two satellites 

 of Uranus was derived from the observations of 

 Sir William Herschel ; and he would not pronounce a 

 decided opinion as to their number or their periods of 

 revolution. 



At last, in the autumn of 1847, Mr. Lassell, of Liver- 

 pool, and M. Struve, at Pulkova, obtained unequivocal 

 evidence of the existence of a third satellite. The orbit 

 of this satellite was evidently smaller than that of either of 

 the two bright ones ; yet the period indicated by LasselTs 

 observations did not agree with that deduced by Struve ; 

 and both differed from the interior satellite of Sir 

 William HerscheL While Lassell's observations in- 

 dicated a period of about two days, Struve deduced 

 from his observations a period of four days; and the 

 time assigned by Herschel to his interior satellite was 

 nearly six days. Thus the question seemed involved in 

 total confusion, and the honest enquirer might well be 

 puzzled to decide whether there existed three satellites, 

 or only one, interior to the two brighter ones. 



In the autumn of 1851, Mr. Lassell succeeded in 

 settling this vexed question. On ten different nights in 

 the months of October, November and December, he saw 

 simultaneously four satellites, and recorded their positions. 



