HERSCHEL THE DISCOVERER. 23 



of man : besides, the discovery enlarged the 

 diameter of the Solar System from 886 to 

 1772 millions of miles. Throughout his life- 

 time Herschel referred to the planet as the 

 "Georgium Sidus," out of gratitude to George 

 III. for appointing him King's Astronomer; but 

 the astronomers of France and Germany, who, 

 as Sir Robert Ball remarks, " saw no reason 

 why the King of England should be associated 

 with Jupiter and Saturn," opposed this term. 

 Lalande called the planet " Herschel," but 

 Herschel's countrymen, the Germans, named it 

 Uranus, in keeping with the custom of desig- 

 nating the planets from the Greek mythology. 

 The name of Uranus ultimately prevailed. 



In January 1787 Herschel discovered two 

 satellites to Uranus, with the aid of his 20- 

 foot telescope. These satellites he believed to 

 revolve round Uranus in 8 days and 13 days 

 respectively, and accordingly he made a draw- 

 ing of what their positions should be on 

 February 10. On that day he found them in 

 their predicted places. In 1797 he announced 

 that the satellites revolved round Uranus in 

 orbits at right angles to the ecliptic, and in 

 a retrograde direction. In subsequent years 

 Herschel believed that he had discovered other 

 four satellites to Uranus, but he was unable 



