Chap". TO. 



of impulfc or ftroke that the airc givcch thole dcnfer bodicsjbui 

 by way of containing them in it, and carrying them with it, fo 

 tiiat it givcth them no more celerity, then to make them go with 

 it fclf, and as parts of it felf. 



Then, Jet him confidcr, that light or fire, by much beating 

 upon the earth, dividcth fbme lude parts of it from others: 

 whereof if any do become fo finall and tractable, as not to ex- 

 ceed the ftrength which the rayes have to manage them; the re- 

 turning rayes, will at their going back, carry away with them 

 or drive before them, fuch little atomes as they have made or 

 nacet with :& fb fill the aire with little bodies cut out of the earth. 

 After this, let him confider that when light carrieth up an 

 atome with it, the light and the atotne do ftick together, and do 

 make one amending body; in fijch fort as when an empty difh 

 lyeth upon the water, the aire in the difli maketh one dependent 

 fcxxiy together with the difh it felf: fo that the denfity of the 

 whole body of airc and dilli ( which in this cafe, are but as one 

 body)is to be efteemed according to the denfity of the two parts; 

 one of them being allayed by the other, as if the whole were 

 throughout of fuch a proportion of denfity, as would arife out of 

 the compofition and kneading together the feveraH denfities of 

 thole two parts. Now then, when thcfe little compounded bodies 

 of light and earth, are carried up to a determinate height ; the 

 parts of fire or light, do by little and little break away from 

 them: and thereby, the bulk of the part which is left, becometh 

 of a different degree of denfity (quantity for quantity ) from 

 the bulk of the entire atome, when light was part of it : and 

 confequently it is denfer then it was. 



Befides, let him confider that when thefe bodies afcend; they 

 do go from a narrow room to a large one > that is , from the 

 centerwards to the circumference: but when they come down 

 again, they go from a larger part to a narrower. Whence it fol- 

 loweth, that as they dcfcend, they draw clofer and clofer toge- 

 ther, and by confequence, are fubjeS to meet and to fall in one 

 with another; and thereby to increafe their bulk, and to become 

 more powerfull indenfity; notonely, by the loflc of their fire; 

 but alfo by the encreafe of their quantity. And fo it is evkkat* 

 that they arc denfer coming down, then going up. 

 Lafily,let him confidcr 3 tjhat thole atomes which went up firft, 



C 2 and 



