THE INNER PLANETS. 99 



from his house at Bremen, Olbers was struck 

 by the presence of a strange object near the 

 path of the planet. At first he supposed it to 

 be a variable star at maximum brilliance, but 

 a few hours showed him that it was in motion, 

 and was therefore another planet. He named 

 it Pallas, and propounded the theory that the 

 two "Asteroids" so named by Herschel were 

 fragments of a trans - Martian planet, which, 

 through some accident, had been shattered to 

 pieces in the remote past. Olbers urged the 

 necessity of searching for more small planets. 

 His advice was taken. In 1804 Karl Ludwig 

 Harding (1765-1834), Schroter's assistant, dis- 

 covered Juno, and Olbers himself detected Vesta, 

 March 29, 1807. 



After 1816 the search was relinquished, as 

 no more planets were discovered. In 1830, 

 however, a German amateur, Karl Ludwig 

 Hencke (1793-1866), ex-postmaster of Driessen, 

 commenced a search for new planets, which was 

 rewarded, after fifteen years, by the discovery 

 of Astrsea, December 8, 1845. On July 1, 1847, 

 he made another discovery, that of Hebe. A few 

 weeks later, John Russell Hind (1823-1895), the 

 English astronomer, discovered Iris. Since 1847 

 not a year has passed without one or more planets 



