Resisting Medium. 247 



their condensation ; unless, indeed, it be assumed that it has ever 

 penetrated alike the interstices between the particles of solid, fluid 

 and aeriform bodies ; an assumption which might involve us in 

 unauthorized conclusions. ^ 



If this medium be possessed of gravity, as we might consist- 

 ently presume, especially since it must otherwise tend to recede 

 from the sun and planets into infinite space, leaving them and 

 their satellites to revolve in vacuo ; it may be considered as a 

 circumsolar atmosphere, subject to the usual laws of atmospheric 

 density and limitation, modified by its vast extent, its extreme 

 tenuity, by any relevant peculiarities it may possess, and by the 

 present and past condition and changes of the system. 



In objecting then to the prevalent opinion state '■. at the com- 

 mencement of these remarks, it seems that we are authorized, by 

 the state of such known facts, analogies and principles as relate 

 to the subject, and by the condition and position of the argument, 

 to presume that the resisting medium is finite in extent ; and that, 

 being so constituted as to obey the laws of physical mechanics, 

 its particles, if once in a state of revolution about the sun, would 

 have a tendency to continue their motions, upon the same princi- 

 ples according to which the planets describe their respective orbits. 

 And therefore, whatever may have been its primary condition, it 

 must have, in the existing state of things, motions consentaneous 

 with those of the sun and planets, which have been so long re- 

 volving in it, in the same angular direction, and in nearly the 

 same plane ; since it could require a small fraction only of their 

 momenta, lo communicate rotation to a medium so rare as to im- 

 pede very little bodies of immense magnitude, yet incapable of 

 disturbing sensibly the satellites of Jupiter, when in close prox- 

 imity. 



Again, as the planets nearest the sun revolve most rapidly, the 

 angular velocity of the ether must also vary with the distance. 

 Supposing it to have ever been continuous, the exterior portions 

 would be accelerated by the friction of those near the centre, until 

 the centrifugal force should exceed the centripetal, when the for- 

 mer would begin to recede, thereby producing a successive sepa- 

 ration into zones, upon principles somewhat analogous to those 

 according to which, a similar arrangement of the primeval belts 

 of planetary vapors is alleged to have taken place. Whatever 

 may have been its original condition, it would be difficult to con- 



