6 SX tije ©ethnical ©n'gine 



of the neighbouring bodies, or other 

 Mechanical Circumftances, the agi- 

 tated Corpufcles can continue their 

 motion with lefs refiftance upwards 

 than any other way, (as either down- 

 wards or horizontally.) And if, as 

 'tis highly probable, that which in 

 light bodies, or at leaft in moft of 

 them* is wont to pafs for pojitive Le- 

 vity, be but a lefs degree of gravity 

 than thatofthofe contiguous bodies 

 that raife them 5 it will happen, that 

 in very many cafes, (for I fay not in 

 all) the great proportion of the fur- 

 face of a Corpufcle to its bulk,(which 

 is ufually greater in the leffer parti- 

 cles) by making it more apt to be 

 wrought on, either by the air agita- 

 ted by the fire^ or by the effluvia of 

 kindled fuell, or by the impulfe of 

 the (haken Corpufcles of the body it 

 felf, will much facilitate the elevati- 

 on of fuch a minute particle, by ex- 

 pofing a greater portion of it to the 

 aftion of the agent, as it will often- 

 times alfo facilitate the renewed fu- 

 ftentation of fuch a fmall body in the 



air, 



