SECTION III. 



THE DISCOVERY OF AN EIG-HTH SATELLITE OF SATURN. 



SATURN has long been known to be attended by seven 

 satellites. "If we number these satellites in the order of 

 their distances from the primary, the sixth was discovered 

 by Huygens in 1655, the seventh by Cassini in 1671, the 

 fifth by the same in 1672, the third and fourth also by 

 Cassini in 1684. The first and second were discovered 

 by Dr. Herschel in 1789. The five satellites first dis- 

 covered may be seen by a ten feet achromatic ; but the 

 two interior satellites can only be seen by a very power- 

 ful telescope. Sir John Herschel, at the Cape of Good 

 Hope, in 1836 and 1837, repeatedly observed the second 

 satellite with his reflector of 18 inches aperture ; and in 

 one instance only, he caught a glimpse of a point of light, 

 which he suspected to be the first satellite. Mr. Lassell, 

 with his large reflector, obtained three observations of the 

 first satellite, in 1846. Sir John Herschel has proposed 

 to distinguish these satellites by proper names, as fol- 

 lows : 



1. Mimas, which makes its revolution in Od. 22h. 36m. 



2. Enceladus, 



3. Tethys, 



4. Dione, 

 6. Rhea, 



6. Titan, 



7. lapetus, 



1 8 53 



1 21 18 



2 17 44 

 4 12 25 



15 22 41 



79 7 54 



