( $^66 ) 
matter than Air doth without difficulty penetrate Glafs, 
Water, Quickfilver, and all other bodies , which we find 
impenetrable to Air j I know not whether he oi^aDjwithout 
any difficulty (as the words feem to importj) or (as I con- 
jefture by what follows) without ^rk# difficulty^, though 
But his Lord&ip (ifj miftake not) though he allowhis 
(SpriDgy)Subtile matter to penetrate Glafijyet not without 
difficulty jaodjtill it have fome room made (as HD)whcrciQ 
it may recoiled: it {elf^ cannot exert its Spring , and there- 
fore not while top-full of clcanfed Quickfilver5 but^ fo 
foon as fome room is made for it ; Whereas, iftheQuicb 
filv^r be noc purged of Air, that little Air remaining doth 
by ks Spring begin the motion. 
He thinks it alio not improbable (and if it fo prove , it 
will be a good confirmation of this Hjpothefis,) thsit a large 
but low Tube of Glaft (fhorter than 29 inches) may ftand 
top-full of Quickfilver, though with a fmall hole in the 
Top3 as at K 5 at leftj if immerged in Water, in cafe Air be 
too Subtile for our Mechanicks. 
He might alio, fuitably enough to his own Hypothefis, 
have fo explained himfelf, as to allow his more SubtiJe 
parts of common Air to penetrate Quickfilver, but not 
Glafs 5 and therefore, in cafe of room for it at HDjit might 
through the Stagnant Quickfilver, and that at C, pafs up- 
wards to HD, and there exert its Spring. 
I ftiall forbear to difpute againll: this Hypothefisfor (he 
prefent 5 bccaufc I think it more proper to examine by Ex- 
periment ( which I think hath not yet been done,) whether 
well-purged Quickfilver may not be made to fiaod higher 
than ei, the ordinary ftand^rd, fuppofe at CH,witha void 
fpace about it, as HD. For the ifliie of thi5 Experiment (a- 
mongft others to be after men tioned5)(cems very proper for 
determining of this doubt 5 which therefore I am not wil- 
iing to pre- judge. There is yet another way of explicating 
the fame Hypothefis, without allowing this Subtile matter 
to pierce the GJafs i which is this ; 
Qur 
