526 COSMOS. 



THE SATELLITES OF URANUS. 



" Uranus," says Sir John Herschel, " is attended by 

 satellites four at least, probably five or six." They present 

 a great and hitherto unparalleled peculiarity, viz. that while 

 all satellites (those of the Earth, of Jupiter, of Saturn), as well 

 as all the principal planets, move from west to east ; and with 

 the exception of a few asteroids in orbits not much inclined 

 towards the ecliptic, the satellites of Uranus move from east to 

 west in orbits which are nearly circular, and form an angle of 

 78 58'w r ith the ecliptic very nearly perpendicular to it. In 

 the case of the satellites of Uranus, as well as those of Saturn, 

 the arrangement and nomenclature, according to their distances 

 from the primary, are to be distinguished from the arrange- 

 ment according to the epoch of discovery. According to a 

 private communication from Sir John Herschel (November 

 8th, 1851), Mr. Lassell has distinctly observed on the 24th, 

 28th, 30th of October, and 2nd of November of the above 

 year, two satellites of Uranus, which appear to be situated 

 still nearer to the primary than the first satellite observed by 

 Sir William Herschel, to which he ascribed a period of revo- 

 lution of about 5 days and 21 hours, but which was not recog- 

 nized. The periods of revolution of the two satellites now 

 seen by Lassell were near to 4 and 2 days. Of the satellites of 

 Uranus the second and fourth were first discovered by William 

 Herschel in 1787, then the first and fifth in 1790, and, finally, 

 the sixth and third in 17y4. During the fifty-six years which 

 have elapsed since the last discovery of a Uranus satellite (the 

 third), the existence of six satellites has frequently been un- 

 justly doubted ; the observations of the last twenty years have 

 gradually proved how trustworthy the great discoverer of 

 Slough has been in this as in all other branches of planetary 

 astronomy. Those satellites of Uranus which have been seen 



