30 FUNDAMENTAL LAWS OF 



But are we not further authorized to conclude, 

 that the equator may have gradually shifted to 

 the middle and even the polar latitudes? This 

 hypothesis would enable us to explain the high 

 and uniform temperature which prevailed through- 

 out the northern hemisphere when the higher lati- 

 tudes abounded with tropical plants and animals, 

 a great physical fact which cannot be satisfac- 

 torily accounted for in accordance with the 

 theory of Laplace. The truth is, that his ma- 

 thematical reasonings were founded on the sup- 

 position that all the planets move in nearly the 

 same plane ; whereas it is now admitted by 

 astronomers, that the orbit of Pallas is inclined 

 to the ecliptic at an angle of 34^, and that of 

 two satellites of Uranus at an angle of 78 58'. 

 But these cosmical bodies had not been dis- 

 covered when the Mecanique Celeste was written ; 

 nor had Geology then taken its legitimate rank 

 among the Sciences. 



This brings us to the general theory of plane- 

 tary motion. The leading facts of the solar sys- 

 tem which connect the movements of the heavenly 

 bodies with the agency and laws of caloric, may 

 be reduced to the following propositions. 



1 . That the sun is 882, 000 miles in diameter, 

 and revolves on his axis from west to east, in 

 about twenty-five days. 



2. That planets revolve around the sun, satel- 

 lites around planets, and all of them upon their 



