2<^ ESSAYS A N D OBSERVATIONS 



fo oppofite to each other, fhall hereafter 

 be diHinguifhed by difFerent names. The 

 vis inftta fhrJl be appropriated to that 

 power which is favourable to motion ; 

 leaving the other power which refifts mo- 

 tion to be denominated by the vis iner- 

 ti£y or rather vis refiflentia. 



Though- this vis inertiaehz a power, 

 as obferved, inherent in all matter, there 

 are certain experiments which may appear 

 to clafli with it, and which, upon that ac- 

 count, merit attention. If a round baM 

 be laid upon a horizontal table in vacitOf 

 in which fituation there will be no coun- 

 teradlion of gravity, it is certain, that the 

 fmoother the ball and table are, the re- 

 finance v/ill be the lefs : And they may 

 be made fmoother and fmoother, till the 

 refiftance be quite infenfible. If the re- 

 fiftance do not vanifli altogether, it may 

 be owing to our v/ant of art to make any 

 furfaee abfolutely fmooth. There is no 

 reafon, it may be thought, to afcribe the 

 fmaM remaining rellftance to a fuppofed 

 vif inertiae, v>^hen it can be accounted for 

 by other caufes ; and that it is unphilofo^ 



phical 



