246 NOVUM OROANUM 



by the other piece of root or pellet, or by the rarnrod. We 

 have examples of their escape from tension, in the motion 

 of the air that remains in glass eggs after suction, in strings, 

 leather, and cloth, which recoil after tension, unless it be 

 long continued. The schools define this by the term of 

 motion from the form of the element; injudiciously enough, 

 since this motion is to be found not only in air, water, or 

 fire, but in every species of solid, as wood, iron, lead, cloth, 

 parchment, etc., each of which has its own proper size, and 

 is with difficulty stretched to any other. Since, however, 

 this motion of liberty is the most obvious of all, and to be 

 seen in an infinite number of cases, it will be as well to dis 

 tinguish it correctly and clearly; for some most carelessly 

 confound this with the two others of resistance and connec 

 tion; namely, the freedom from pressure with the former, 

 and that from tension with the latter, as if bodies when com 

 pressed yielded or expanded to prevent a penetration of 

 dimensions, and when stretched rebounded and contracted 

 themselves to prevent a vacuum. But if the air, when 

 compressed, could be brought to the density of water, or 

 wood to that of stone, there would be no need of any pene 

 tration of dimensions, and yet the compression would be 

 much greater than they actually admit of. So if water 

 could be expanded till it became as rare as air, or stone as 

 rare as wood, there would be no need of a vacuum, and yet 

 the expansion would be much greater than they actually 

 admit of. 



We do not, therefore, arrive at a penetration of dimen 

 sions or a vacuum before the extremes of condensation 

 and rarefaction, while the motion we speak of stops 

 and exerts itself much within them, and is nothing more 

 than a desire of bodies to preserve their specific density (or, 



