^/BODIES. Chap. ir. 



way they go ; and that motion, whereby the fpace is enlarged , 

 between the (lone and the flickering rock, muft draw in a grea- 

 ter quantity of airc and atomes to ftrikeupon it. Andthus by 

 Hctle and little, the (tone paffeth through all the degrees oftar- 

 dity by which a defending body parteth from reft : which is by 

 fo much the more fpcedily done, by how much the body is more 

 eminent in denfity. But this difference of time, in regard of the 

 atomes ftrokes onely ; and abftraiting from the bodies denfity; 

 will be infenfible to us; feeing (as we have faid) no more is re- 

 quired of them, but to give a determination downwards. 

 & And out of this, we, clearly fee the rcafon why the fame a- 



Ihy <Wbe- tonics, ftriking upon one body lying upon the water, do make ic 

 iici fink-.oihcrs fink;and upon another they do not. As for example, if you lay 

 upon the ftiperficies of fome water, a piece of iron, and a piece 

 of cork, of equall bigneffe and of the fame figure; the iron will 

 be beaten down to the bottome, and the cork will float at the 

 top. The reafon whereof is, the different proportions of the 

 comparifon of their denfities with the denfitie of water : for fas 

 we have faid) the efficacy and force of defending, is to be mca- 

 fured by that. So then the ftrokes of the atomes, being more ef- 

 ficacious upon water then upon corkj becaufethe denfity of wa- 

 ter is greater then the denfity of cork confidering the abun- 

 dance of aire that is harboured in the large pores ofit ; it fol- 

 lo'.vech, that the atomes will make the water go down more for- 

 cibly then they will cork. But the denfity of iron exceeding the 

 denfity of water ; the fame ftrokes will make the iron defccnd 

 fafter then the water ; and confequently, the iron muft fink in 

 die watej, and the cork will fvvimme upon it. 



And this fame is the caufc, why if a piece of cork be held by 

 force at the bottome of the watcr;i* will rife up to the top of the 

 water, as foon as the violence is taken away that kept it down: 

 for the atomes ftrokes having more force upon the water then 

 upon the cork ; they make the water fink and flide under it ; 

 firft, a little thinne plate of water ; and then another, a little 

 thicker; and fo by degrees more and more, till it hath lifted the 

 cork quite up to the top. 

 7. Fifthly, it may be objected, that thefe atomes do not defcend 



The fifth obj;- alvvayes perpendicularly, but fornctiniesflopinc-ly and in that 

 ftion wifwered r T i a 1 LI r rj r u j i 



concerning the cafe, if their ItroKcs be the caufe of denlc bodies movjng) they 



fhotiid 



