CH. xxxii. SIX JOHN HERSCHEL. 305 



the unknown planet, which he identified from a chart in his 

 possession. So true is the law of gravitation, that two men 

 sitting at home in their studies were enabled, from slight 

 irregularities in the motion of Uranus, to predict the ex- 

 istence and place of a disturbing body, rolling on through 

 space ! This new planet is called Neptune. It is a little 

 larger than Uranus, but so far off that it is not visible to 

 the naked eye. It has certainly one moon, discovered by 

 Mr. Lassell. 



Sir John Herschel' s work in Astronomy. While 

 these different discoveries were being made in the obser- 

 vatories of Europe, Sir John Herschel was at the Cape, 

 sweeping the heavens with his telescope for double stars and 

 nebulae, and measuring their brilliancy. Born at Slough, 

 close to his father's observatory, in 1792, the young John 

 Herschel spent his early life with his father and aunt, 

 and saw them always busy night and day studying the 

 heavens. In 1813 he was Senior Wrangler at Cambridge, 

 and after that he turned his attention to double stars, 

 and in 1818 completed a list of no less than 2000 of 

 these wonderful double and sometimes treble suns which 

 revolve round each other. When he had completed the 

 survey of the whole of our northern skies, he went in 1833 

 to the Cape of Good Hope, taking with him a large tele- 

 scope, for which he built an observatory, and there he 

 spent four years gauging the stars of the southern hemi- 

 sphere, and classing them according to their brilliancy, as 

 his father had classed those of the northern hemisphere. 

 He was thus the first astronomer who swept his telescope 

 over the whole of the heavens which are visible from our 

 planet, and who saw with his own eyes every star, planet, 

 and nebula, then visible in the sky. Among the remark- 

 able appearances which he examined were those cloudy 



