( 8r ) 
orfor preventing of vacuity^there are taken away fucceffive- 
ly fromthefuperficiesof theQuickfilver certain Ica'es as it 
were of an indivifible profundity, ratified into a fubtleiovi- 
fible confifl:encc,which fupply that deferted fpace, and make 
up a kind oi funiculus^ that fufpends the Mercury to the Tube, 
and is coextended to the whole vacant fpace gradually, as the 
Mercury defcended. This way,/ fay, our Author rejefts, al- 
ledging his reafons for doing fo; and fubftitures certain Ef 
fuvU and fubtle fteams/ent out from the Mercury ; affirming^ 
that thefe fteams or vapors arefeparaced from that hody.^rfi^ 
by way oiExpreJ/iof^^ or ftraining them out by the ftrong def- 
cending motion of the Mercury,and the compreflion of the in- 
ferior parts by the fuperior, as alf^, the great agitation of its 
parts ; the grofler Mercurial parts coming clofer together^and 
expelling the mo:e fubtle and vaporous "p^xt^.Secondly ^hy way 
of Extra0m^oT drawing out thofe parts that are more fubtle 
and fluid,and capable of expanfion 5 whence he thlnks'arifeth 
that /»^^ and ^(W^obferved in the defcent of the Mercury, 
And thefe parts thus extraded are, w his ofmm.dihted to as 
great an amplitude and tenfion,as the ftrength of the defcent of 
the Mercury, and the widenefs of the fpace,ic leaves, requireth; 
which tenfion alfo, he faith, contributes much to the retarding 
of the fwifcnefs of the Mercurial defcent.And becaufe at about 
29x inches the weight of the Quickfilver decreafeth to fuch a 
ftate,as cannot work any further feparation of fubtle matter to 
fupply any more room, it ftays there, and defcends no farther, 
not having ftrength enough at that height to feparate any fubtle 
matter from it felf, to fupply the fpace it fliould leave by fuch 
defcent. Where he confiders,that,although the immediat caufe 
of the feparation of the fubtle matter of Mercury, and the ex- 
panfion thereof, be the force of the defcent, weight and pref- 
Ture of the Mercury ; yet this is performed to avoid 
the Diflblution of Continuity, or (which is all one j a 
S . J What is mt the Caufe that faff ends the Cylinder of Mer- 
cury in the Tube to the hight of about 29 inches ; namely, not 
the Gravitation or Preflure ofthe impending Air, nor its Ela- 
fticity ; Where our Author largely examins the doftrine of the 
M Spm^ 
