no ESSAYS AND OBSERVATIONS 



own diredlion. All the world indeed may 

 know that, when a body ftrikes upon clay 

 or other fuch loft matter, a double force 

 may produce a quadruple impreflion. But 

 then, this can only happen in fuch cafes 

 where no other reinlance is worth the 

 minding, but that arifing from the cohe» 

 fion of the matter, in the manner above 

 explained. When a ball moves through 

 a fluid, the refinance proceeds, aim oft en' 

 tirely, from the deniity or inertia; and, 

 the denfity being given, this refiftance 

 muft increafe as the fquares of the velo- 

 city. In this cafe, it would be a vain at- 

 tempt, to afCgn any meafure of the im- 

 preffions ; becaufe, it follows clearly fronn 

 the demonftrations of Sir Ifaac Newton *, 

 that the body would go on for ever. And 

 furely, it requires not much abftradl rea- 

 foning to prove, that mere inertia^ with- 

 out the help of fome adlive power, like 

 gravity, or the attra(5lion of cohefion, 

 could never totally confume any motion, 

 or reduce a body from a ftate of motion 



to 



• Princip, Lib. II, Prop, y, et cor» 



