and J&O&UtftOtt of ftolatftttp* 7 

 air, which refifts more the defcent of 

 particles whofe furfaces are large, 

 than of others of the fame gravity 

 and bulk : As a leaf of paper difplay- 

 ed will much longer hover in the 

 Air, than if it were reduced into a 

 ball or pellet. That this minutenefs 

 of particles may difpofe them to be 

 carried upwards, by the impulfe of 

 other bodies and that of the agitated 

 Air, is very obvious to be obferved : 

 As we fee, that Horfes in a high-way, 

 though they be not able with the 

 ftrokes of their feet to make (tones, 

 or gravel, -or clods of Earth fly up, 

 yet they will eafily raife clouds of 

 duft oftentimes mingled with the 

 fmaller grains of fand. And where 

 Timber is fawing, the fame wind that 

 will not in the leaft move the beams, 

 and fcarce at all move the chips, will 

 eafily carry up the Saw-duft into the 

 Air. And we fee in our Chimneys, 

 that the fmoak readily afcends, whilft 

 even fmall clods of foot, which k but 

 an aggregate of the particles of fmbak, 

 fall headlong down. 



A 4 CHAP. 



