42 ESSAYS AND OBSERVATIONS 



ciple by which to accaunt far this phaz- 

 nomcnon. At the fame time, I cannot 

 difcover any equality of action and re- 

 at5lion in this cafe ; on the contrary, it is 

 eftablifhed by infaUible experiments, thac 

 the imprelTed force or a<5lion is always 

 greater in a determined proportion, than 

 the refiftance or readtion. And it is this 

 very proportion which p«"odiices the effect 

 of an equality of motion before and af- 

 ter impulfe ; or, in other words, the ac- 

 quifition of as much force by the one^ as 

 is loft by the other. 



Another inftance is of a horfe draw~ 

 ing a ftone by a rope ; and it is faid, that 

 the ftone draws the horfe, as much as the 

 horfe the ftone. Were this fo, there could 

 be no motion. All I can difcover here, 

 is mere refiftance in the ftone, occafioned 

 partly by its 'vis 7'efifientUy and partly by 

 fridlion. And after this refiftance is over- 

 come, which fpends or exhaufts fo much 

 of the horfe's ftrength, the ftone is drawa 

 along with the horfe's remaining ftrength, 

 without any further refiftance» 



Wit IT 



