and the Mode of its Communication. 107 



living forces residing in them to the never-ceasing 

 motions of their constituent particles than to sup- 

 pose them to be derived from their want of power, and 

 their total indifference to motion and to rest. 



No reasonable objection against this hypothesis (of 

 the incessant motions of the constituent particles of all 

 bodies), founded on a supposition that there is not 

 room sufficient for these motions, can be advanced ; 

 for we have abundant reason to conclude that if there 

 be in fact any indivisible solid particles of matter 

 (which, however, is very problematical), these particles 

 must be so extremely small, compared to the spaces 

 they occupy, that there must be ample room for all 

 kinds of motions among them. 



And whatever the nature or directions of these inter- 

 nal motions may be among the constituent particles of 

 a solid body, as long as these constituent particles, in 

 their motions, do not break loose from the systems to 

 which they belong (and to which they are attached by 

 gravitation), and run wild in the vast void by which 

 each system is bounded (which, as long as the known 

 laws of nature exist, is no doubt impossible), the form 

 or external appearance of the solid cannot be sensibly 

 changed by them. 



But if the motions of the constituent particles of any 

 solid body be either increased or diminished, in conse- 

 quence of the actions or radiations of other distant 

 bodies, this event could not happen without producing 

 some visible change in the solid body. 



If the motions of its constituent particles were dimin- 

 ished by these radiations, it seems reasonable to con- 

 clude that their elongations would become less, and 

 consequently that the volume of the body would be 



