246 HISTORY OF PHYSICAL ASTRONOMY. 



Lexell's, which, in 1770, appeared to be revolving in 

 a period of about five years, and whose motion was 

 predicted accordingly. The prediction was disap- 

 pointed; but the failure was sufficiently explained 

 by the comet's having passed close to Jupiter, by 

 which occurrence its orbit was utterly deranged. 



Thus, no verification of the Newtonian theory, 

 which was possible in the motions of the stars, has 

 yet been wanting. The return of Halley's comet, in 

 1835, and the extreme exactitude with which it 

 conformed to its predicted course, is a testimony of 

 truth, which must appear striking even to the most 

 incurious respecting such matters (P). 



Sect. 6. Application of the Newtonian Theory to 

 the Figure of the Earth. 



THE Heavens had thus been consulted respecting 

 the Newtonian doctrine, and the answer given, over 

 and over again, in a thousand different forms, had 

 been, that it was true; nor had the most perse- 

 vering cross-examination been able to establish any 

 thing of contradiction or prevarication. The same 

 question was also to be put to the Earth and the 

 Ocean, and we must briefly notice the result. 



According to the Newtonian principles, the form 

 of the earth must be a globe somewhat flattened at 

 the poles. This conclusion, or at* least the amount 

 of the flattening, depends not only upon the exist- 

 ence and law of attraction, but upon its belonging 



