LABOURS RELATIVE TO THE SOLAR SYSTEM. 295 



On the 28th of August, 1789, the great forty-foot 

 telescope revealed to Herschel a satellite still nearer to 

 the ring than the other five already observed. Accord- 

 ing to the principles of the nomenclature previously 

 adopted, the small body of the 28th August ought to 

 have been called the first satellite of Saturn, the num- 

 bers indicating the places of the other five would then 

 have been each increased by a unity. But the fear of 

 introducing confusion into science by these continual 

 changes of denomination, induced a preference for calling 

 the new satellite the sixth. 



Thanks to the prodigious powers of the forty-foot 

 telescope, a last satellite, the seventh, showed itself on 

 the 17th of September, 1789, between the sixth and the^ 

 ring. 



This seventh satellite is extremely faint. Herschel, 

 however, succeeding in seeing it whenever circumstances 

 were very favourable, even by the aid of the twenty- 

 foot telescope. 



The discovery of the planet Uranus, the detection of 

 its satellites, will always occupy one of the highest places 

 among those by which modern astronomy is honoured. 



On the 13th of March, 1781, between ten and eleven 

 o'clock at night, Herschel was examining the small stars 

 near H Geminorum with a seven-foot telescope, bearing 

 a magnifying power of 227 times. One of these stars 

 seemed to him to have an unusual diameter. The cele- 

 brated astronomer, therefore, thought it was a comet. It 

 was under this denomination that it was then discussed 

 at the Royal Society of London. But the researches of 

 Herschel and of Laplace showed later that the orbit of 

 the new body was nearly circular, and Uranus was ele- 

 vated to the rank of a planet. 



