[loioj 
its fpring, being lb many and evident, beyond excep- 
tion. 
And, that this fpring of the Air, is fome times ftrongerr 
andfometimes weaker, I think is undoubted alfo. And, 
that the fpring ot the^^V, is ftrengthened both by com-T 
preffion, and by heat, but in a different manner. 
It the fame quantity of ^/r be Gompreffed into a lefler 
_ room, the fpring is certainly ftronger. As is undoubted- 
ly feen in the Wind-Gun, and other compreflive En- 
gines. And from hence it is, that^/r, of the commoa 
texture with the external or open -^?V, if it be (retaining 
its own texture, j included in a clofe Veffel ( as in the Air- 
Tump,) whereby it is excluded from communication with 
theexterual ^/r, and defended from the preffureot it, 
doth yet fuftain ^icJ^Silver in a Tube Cafter the Torri- 
cellian manner,) at as great an high t, as the opea. Air by 
its counterpois would have done. Which cannot be by 
its weight (which, ia this caufe, is but fmall j and not e- 
qual to that of acylinder thereof contained to the height 
of the ^-!^;72«?/^A^r^;) but by its fpring only; which is now 
jgrefled to as great a degree as it was in the open Air (by 
luch weight as" was then incumbent on it,) or would be 
now, if lo again expofed. TLike as that of a Fleece of 
Wooll would be, if confined to the fame dimenfionsit 
had, when a great pile of Fleeces was incumbent, on it. ) 
But if fome of this Air fo included (in the Air-Fump or 
fuch other clofe VefFels,; be Fumped out, whereby the 
refidue thereof hath a greater room to pofTefs then before 
ithad>^ ^namely, as much before the whole of it did pot 
fefs,) the ^^V^A/zr^r will prefently fubfide, becaufe the 
fpring of the Air which did before fuftain it, is now (by 
expanfion,) become weaker. 
iigain-, the fame quantity of included ^/r in a clofe 
VelTel (fo as not to communicate with the external 
will,by application of heatto it, have its fpring ftrength- 
ened, and drive its coqnterpois f arther off,, or (if need 
be^ 
