Resisting Medium. 249 



1st. The circumferences of circles being as their radii, and 

 gravity inversely as the square of the distance; the centrifugal 

 force of portions remote from the primary, at length exceeding 

 the force of attraction, must cause them to recede ; and this pro- 

 cess must continue as long as the momenta of the planet and its 

 satellite continue to be transmitted to the circumference of its 

 tenuous atmosphere. 



2nd. The rotation of any mass having motions similar to those 

 of the planets, must, as might easily be proved, have a tendency 

 to remove a resisting medium from its path, and therefore if ever 

 the ether were so disposed as to interfere with the motions of the 

 planets and their satellites, it must, unless retained by causes of 

 whose existence we are not apprised, recede from the vicinity of 

 their orbits. 



3rd. So much of the ether as should nevertheless be retained . 

 by the attraction of any of these bodies, would probably be dis- 

 posed in concentric zones, analogous to those in the general sys- 

 tem, and upon similar principles ; after the separation of which 

 zones, the influence of a resisting medium would cease to be felt, 

 at least until their arrangement should be disturbed. 



4th. And finally, as the magnitude of the planetary bodies was 

 probably much greater formerly than at present, it may be pre- 

 sumed that most of these changes occurred before the process of 

 condensation was completed. 



The ether once distributed throughout the system as has been 

 indicated, and with the elements of readjustment, must resist the 

 action of a disturbing force. A cause of disturbance exists in the 

 excentric motions of comets, which in their course must necessa- 

 rily displace portions of the intersected zones. But this cause can 

 hardly exceed the force requisite to render their present orbits 

 consentaneous with the general motions of the system. Besides, 

 while it acts with exceeding slowness in widely distant regions, 

 it operates at the two intersections of each zone made in a revo- 

 lution, in nearly opposite directions ; and therefore comparatively 

 feeble as the resulting forces must be, under any circumstances, 

 it is possible that in consequence of its mode of operation, this 

 cause may effect little else than temporary oscillations of the me- 

 dium until it ceases to act. 



The consideration of influences and consequences foreign to 

 the system, has been thus far, for the most part, purposely avoided. 



Vol. XXXVIII, No. 2.— Jan.-March, 184Q. 32 



