192 HERSCHEL AND HIS WORK 



will be thousands perhaps thirty thousand more yet 

 discovered." The discovery of the fourth, called Vesta, 

 he pronounced " an event of such consequence " as to 

 " engage his immediate attention." He called it " a valu- 

 able addition to our increasing catalogue of asteroids " ; 

 and he spoke of the " celebrated discoverers " as in- 

 ducing " us to hope that some farther light may soon 

 be thrown upon this new and most interesting branch 

 of astronomy." 1 Dr. Olbers himself wrote to Herschel 

 that Vesta " was not to be distinguished from a fixed 

 star " ; 2 while Schroeter, the countryman and neighbour 

 of Olbers, had already communicated a paper to the 

 Royal Society in which he said : 3 " Its image was, with- 

 out the least difference, that of a fixed star of the 6th 

 magnitude with an intense radiating light; so that 

 this new planet may with the greatest propriety be 

 called an asteroid." That one scientific man should 

 attack, or rather slander, another for giving to these 

 small bodies a scientifically appropriate name, on the 

 ground that he thereby intended to derogate from the 

 credit of his own friends, whom he publicly extolled as 

 " celebrated discoverers," seems incredible. Yet it was 

 done. 



By a most ingenious contrivance he managed to 

 obtain approximate values for the diameters of Ceres 

 and Pallas. The former he found to be 161'6 miles ; 

 the latter smaller, 147 or 110J miles. So small is 

 Pallas that it would require many thousands equally 

 small to make up a planet no larger than Mercury. 

 The colour of Ceres he found to be " ruddy, but not 

 very deep " ; that of Pallas, " milky whitish." 



1 Letter from Dr. Olbers, April 20, 1807. 



2 Phil. Trans., 1807, p. 260. 3 Phil. Trans., May 28, 1807, p. 245. 



