94 THE WONDERFUL CENTURY. CHAP. xi. 



suspected a planet ought to be found, because the dis- 

 tance between these older planets was so great as to be 

 quite out of proportion with the regular increase of dis- 

 tance maintained by the other members of the system. 

 It was at first thought that these asteroids or minor 

 planets were the shattered remains of a much larger one ; 

 but more extended knowledge of the constitution of the 

 solar system renders it more probable that they really 

 constitute a ring of matter thrown off by the sun during 

 its progressive contraction; and that some peculiar con- 

 ditions have prevented its various parts from aggregat- 

 ing into a single planet. This is rendered more probable 

 by two other remarkable discoveries relating to meteors 

 and comets, and to Saturn's rings, which will be dis- 

 cussed later on. 



The next large planet added to our system is especially 

 interesting, as affording a striking demonstration of the 

 theory of gravitation, and a no less striking example of 

 the powers of modern mathematics. It had been found 

 that the motions of Uranus were not exactly what they 

 ought to be, if due solely to the attraction of the sun and 

 the disturbing influence of Jupiter and Saturn, and it 

 was thought possible that there might be another planet 

 beyond it to cause these irregularities. In the year 

 1843 a young Cambridge student (John Couch Adams) 

 of the highest mathematical ability, determined to see 

 whether it was not possible to prove the existence of such 

 a planet; and having taken his degree as Senior 

 Wrangler, he at once devoted himself to the work, and 

 after two years of study and calculation he was able to 

 declare that a planet which would account for the per- 

 turbation of Uranus must, if it existed, be at that time in 



