226 THE OCEAN. [Book X. 



PEOPOSITION I.' 



Theorem. — If one of any two bodies in space be 

 moved in such a manner as to increase the dis- 

 tance between the two, the other tends to follow 

 with the same motion. 



Because the force of gravitation tends to hold 

 them together, and, therefore, if one be moved by 

 an extraneous force, the other is drawn in the same 

 direction by the action of their gravitation towards 

 each other. 



Corollary. — For the same reason the gravitation 

 towards other bodies will tend to keep the second 

 body in its position ; and, therefore, between the two 

 forces it can neither remain at rest nor move with 

 the full velocity of the first. 



' It must be borne in mind that the theory under demon- 

 stration in this Book is one arrived at by induction from the 

 investigation of the movements of the ocean, not invented for the 

 pui-pose of explaining the cause of the movements of the planets. 

 From the movements of the latter corroborative evidence of the 

 truth of what I consider already established as the cause of the 

 movements of the ocean is given in such a manner that the i-esult 

 arrived at shows that the conflicting action of terresti'ial and astral 

 gravitation is of necessity tending to cause the system of oceanic 

 circulation described in Book II, 



