190 HERSCHEL AND HIS WORK 



habit of excluding light from surrounding objects by 

 wearing a black hood. 



Herschel was not content with wresting from Uranus 

 this novel part of his story. He continued to watch 

 the planet. Unfortunately, the same success did not 

 crown his efforts to read its history. A great number 

 of observations on imaginary rings and supposed 

 moons, that were found to be stars, or not moons but 

 probably moving, planetary bodies of the asteroid 

 nature, demanded his attention, and deceived his 

 hopes. It was such a tantalising pursuit, that even 

 "the direction of a current of air alone may affect 

 vision." At last he came to the conclusion that no 

 ring, similar to Saturn's, girdles Uranus; but that, 

 certainly, four additional satellites accompany him on 

 his long journey of eighty-four years round the sun. 

 Astronomers who came after his time failed to find 

 these four moons, but, later still, two satellites have 

 been added to the original two discovered by Herschel. 

 One of the additions is suspected to belong to the four 

 he believed he had seen circling round the planet. Of 

 the four recognised satellites the most distant, Oberon, 

 performs its round in 13 '46 days, or, as Herschel 

 found, 13 days, 11 hours, 5 minutes, 1 seconds. Other 

 information, which by careful watching he wrung 

 from Uranus, has been verified or corrected by those 

 who came after him ; but to this unwearied observer 

 belongs the credit of showing that the two satellites 

 he discovered, unlike other members of the solar 

 system, revolve in orbits nearly at right angles to 

 the ecliptic, and that their course is retrograde, or 

 from east to west, not direct, that is, from west 

 to east. These were two singular and outstanding 



