PHYSICAL AND LITERARY. sS 



f^ the empty celeftial fpaces becweea them. 

 " An4, ia paffing from them to great di- 

 f* ftances, that it grows deafer aad dea> 

 " fer perpetually ; and thereby caufes 

 ," the gravity of thofe great bodies towards 

 ** one another, and of their parts towards 

 ." the bodies; every body endeavouring 

 ?* to go from the denfer pare of the me- 

 ." dium towards the rarer." I am not 

 better fatisfied with this hypothefis than 

 that of Des Cartes. For, vrithout loofing 

 time upon a minute inquiry into the ve- 

 ry peculiar properties with which thi§ 

 fuppofed aether muft be endued, in or- 

 der to produce the efFedls affigned it ; the 

 fame objection lies againft it, that is a- 

 boye urged againft the vortices of Des 

 Cartes, that it is a new fpecies of mat- 

 ter invented without evidence, and indeed 

 without neceffity : For it is as eafy to en^ 

 due the planets with a power which im- 

 pells them towards the fun, as to endue 

 this fuppofed aether with a power which 

 repells it from the fun. Therefore the 

 argument which is juftly urged by this 



author himfelf againft a plenum in the 



sStk 



