2 2 VESTIGES OF THE 



and moving nearly at the same distance from the sun, 

 though in orbits so elliptical, and of such different 

 planes, that they keep apart. 



It has been seen that there are mathematical propor- 

 tions in the relative distances and revolutions of the 

 planets of our system. It has also been suggested that 

 the periods in the condensation of the nebulous mass, at 

 which rings were disengaged, must have depended on 

 some particular crises in the condition of that mass, in 

 connection with the laws of centrifugal force and attrac- 

 tion. M. Comte, of Paris, has made some approach to 

 the verification of the hypothesis, by calculating what 

 ought to have been the rotation of the solar mass at the 

 successive times when its surface extended to the various 

 planetary orbits. He ascertained that that rotation cor- 

 resjjonded in every case with the actual sidereal revolution 

 of the jj»/rt/i?^5, and that the rotation of the jorimarij j^lcmets 

 ill nice manner corresponded with the orhitual 2^€riods of 

 the secondaries. The process by which he arrived at this 

 conclusion is not to bo readily comprehended by the 

 unlearned ; but men of science allow that it is a powerful 

 support to the present hypothesis of the formation of 

 the globes of space. ""' 



* M. Conite comLincil Hiij-gens's tlicorenis for llic incasnvc of 

 centrifugal force with the law of gravitation, and thus formed a 

 f^imple fundamental equation between tlie duration of tlie rotation of 

 what he calls the producing sta-, and the distance of the star pro- 

 d'lccd. The constants of this equation were tlie radius of tlie central 

 star, and the intensity of gravity at its surface, which is a direct con- 

 sequence of its mass. It leads directly to the third law of Kepler, 

 A^hich thus becomes susceptible of being conceived d priori in a 

 cosmogonical point of view. M. Comte first applied it to the moon, 

 and found, to his great delight, that the periodic time of that satellite 

 agrees within nn linnr or two with the dm-allon which the revolution 

 of the earth ought to Inve had at the lime when the hmar distance 

 formed the limit of ihe earth's atmosphere, lie fouu 1 the coincidence 



