SIR WM. AND CAROLINE HERSCHEL. 99 



the telescope February 19, 1787. George III. gave 

 twenty thousand dollars for the building of this in- 

 strument, and one thousand dollars yearly for its 

 maintenance. 



A half-century afterwards, the woodwork having 

 become decayed, it was taken down, the great tube 

 laid horizontally, and, after Sir John Herschel and 

 his family had passed through it, a poem written 

 by Sir John having been read, it was sealed Jan- 

 uary 1, 1840, and placed on piers. 



With this great telescope, Herschel discovered 

 two satellites of Saturn, Mimas and Enceladus ; one 

 on August 27, 1789, and the other on September 17 

 of the same year. Two years before this, January 

 11, 1787, he discovered two satellites of Uranus, 

 Oberon and Titania. Sixty years afterwards, Mr. 

 Lassell, of England, discovered the remaining two 

 satellites of Uranus, called Ariel and Umbriel. 



From this time his work went forward grandly. 

 He had already completed more than two hundred 

 seven-foot, one hundred and fifty ten-foot, and 

 eighty twenty -foot mirrors. For many of the 

 telescopes sent abroad he made no stands, but 

 provided the drawings. He wrote much about 

 Saturn and its rings, and showed that.its most 

 distant satellite, Japetus, turns once on its axis 

 in each revolution about its primary, as our moon 

 does about the earth. 



He studied carefully the nature of the sun, its 

 probable gaseous surface, and its spots, and was 

 the first to suspect their periodic character. What 



