SECTION IV. 



ON THE SATELLITES OF URANTJS. 



UKANUS was discovered to be a planet by Sir William 

 Herschel in 1781, and in 1787 he discovered two satellites, 

 wliose periods were satisfactorily determined by his sub- 

 sequent observations. In 1797 he announced the dis- 

 covery of four additional satellites, viz., one within the 

 orbits of both the former two ; one intermediate between 

 the two; and two exterior to both of them, but the 

 periods of these satellites he acknowledged to be very 

 uncertain. In his last paper on this subject, commu- 

 nicated to the Eoyal Society in 1815, he says, "that there 

 are additional satellites, besides the two principal larger 

 ones, I can have no doubt ; but to determine their number 

 and situation, will probably require an increase of illum- 

 inating power in our telescopes." 



In 1834, Sir John Herschel published a paper contain- 

 ing a thorough discussion of his father's observations, 

 together with his own, upon the two satellites first dis- 

 covered ; and he adds, " of other satellites than these 

 two, I have no evidence." 



In the year 1838, Dr. Lamont, of Munich, published a 

 few observations of the two brighter satellites of Uranus, 

 and states that he had seen only one additional satellite, 



