PHYSICAL AND LITERARY. 6i 



tion, from its varying cfFedis, to conclude 

 gravity to be a varying power. In fliort, 

 when acceleration is produced by an ex- 

 ternaj caufe, it vv^ill be evident to every 

 one, that the force of .the impulfive caufe 

 piuft be continually increafing, to pro- 

 duce fuch an effect j and it will be a hard 

 talk to affign any juft foundation for a 

 (difference in this particular, betwixt ex- 

 ternal and internal force» 



We muft therefore yield to the difficul- 

 ty, becaufe it is unfurmoun table. It is 

 very true, that a body has, quam proxime^ 

 the fame weight at the diftance of tea 

 foot from the furface of the earth, as at 

 the diftance of ^ hundred: And the force 

 of gravity is, quam proxime, the fanie 

 when a body is 4ropt from the hand at 

 thefe different diftances. But then, tho' 

 gravity is fuppofed invariable, vvhere the 

 difference of the diftances is fo fmall j 

 yet this only holds where other circum- 

 ftances are the fame: That is, where the 

 body is either at reft, or moves with the 

 fame celerity. For it is extremely clear, 

 that, in the perpendici;lar defcent of a 



body, 



