180 



Mr. 

 White. 



That bodies 

 rmy be rarifi- 

 ed, both by 

 omward and 

 inwardTiear; 

 and how tlii* 

 ijKi formed. 



A Treatife of B O D I E S. Chap. 1 7. 



this Ocean, and to begin a new voyage of navigation upon it : 

 unleflc he were a(Tured, he bad ballaft enough in his fhipto 

 make her fink deep into the Water and to carry her fteddily 

 through thofe unruly waves ; and that he were furniflied with 

 skill & provlfion fufficicnt to go through , without either lofing 

 his courfeby fleering after a wrong compafle> or being forced 

 back again with fhort and obfcure relations ofdiicoveries : fince 

 others that went out before him, are returned with a large ac- 

 count to fuch as are able to understand and fummc it up. Which 

 iurely our learned countreyman,and my beft and moft honoured 

 friend, and to whom of all men living I am mort obliged ffor to 

 him I owe that little which I know; and what I have,and fliall 

 Jet down in all this di/courfe, is but a few (parks kindled by me 

 at his great fire)hath both profbundly,and acutely, and in every 

 regard judicioufly performed in his Dialogues of the world* 



Our task then (in a lower ftrain; and more proportionate to 

 fo weak flioulders) is to look no further then among thofe bo- 

 dies we converfe withall. Ofwbichi having declared by what 

 courfeand engines nature governeth their common motions, 

 that are found even in the Elements, and from thence are deri- 

 ved to all bodies competed of them ; we intend now to confidcr 

 fuch motions as accompany divers particular bodies, and are 

 much admired by wholbevcr underftandtth not the caufes of 

 them. 



To begin from the eafieft and moft connexed with the acti- 

 ons of the Elements, the handfell of our labour will light upon 

 the motions of Rarcftftion And. Condtfati9 y as they arc the 

 paflions of mixed bodies. And firft for Rarefaction ; we may re- 

 mercbcr how it proceedeth originally from fire, and dependeth 

 ofheat;as is declared in the former chaptcrrand wherefoevcr we 

 find Rarefailion,we may be confident the body which fuffereth 

 it,is not without fire working upon it. From hence we may ga- 

 thcr,that when the aireimprifbned in a baloonor bladder,fwel- 

 Jcth againft whatcontaineth it;andftretcheth its cale, and feek- 

 eth to break out ; this effcifc muft proceed from fire or heat 

 f though we fee not the firc)working either within the very bow- 

 els of the airc, or without, by prelTing upon what containeth 

 ir, and ib making it fclf a way unto it. 



, And that this latter way is able to yvork this effect , may 



be 



