72 ESSAYS AND OBSERVATIONS 



are equal ; confequently that their forces 

 are as their quantities of matter multipli- 

 ed upon their velocities ; and therefore 

 that the force of the fame body is always 

 as its velocity. A thoufand different ex- 

 periments of the fame kind, make it evi- 

 dent, that the force of every moving bo- 

 dy is in the precife ratio of its velocity. 

 And thofe experiments muft be abfolute- 

 ]y unexceptionable, in which we compare 

 the force of one body with the force of an- 

 other equal body moving with a different 

 velocity ; for this is in effedl comparing 

 the different forces of the fame body mo- 

 ving with different velocities. 



It being thus afcertained, that the 

 force of a body moving by the vis inftta 

 is always in proportion to its velocity, 

 we have reafon to conclude, from analo- 

 gy, that the fame rule holds where bo- 

 dies move by the force of gravity. And 

 accordingly this is alfo made evident 

 from a courfe of unexceptionable experi- 

 ments. 



The 



