( 202 1 ) 
water : For though, whilft they lay concealed In the watcr^ they 
took up fo little room init^ that it was infenfibJe 3 and when they 
were permitted to efcape out of the Tube 5 the water was noc 
manifeftly diminifhed by their receffe 5 yet when they were affb- 
ciated at the top of the Tube , their aggregate did foinetimes 
maintain a place 5 that was confiderable enough in reference to 
the capacity of the whole Tube, though I muft here adverrife^ 
that this Aggregate did at the top of the Tube poflefi more room 
than its bulk did abfolutely require 3 becaufe it was foniewhat 
defended from the prefliire of the Atmofphere by the weight of 
thefubjacent Cylinder of water, which might be about three or 
four foot long. - 
^ere : Whether any confiderable proportion of Bubbles will 
be atforded by the fame liquor, if it be fuffered to continue in the 
glals for fome competent timej after it has been oncej^or oftenerj 
freed from bubbles already ? 
^ert : How far it may be worthy our confideration, whether 
\ in common water there may not be concealed Air enough to be 
of ufe to fuch cold Animals as Fijhes-^ and v/hether it maybe fe- 
parable from the warer, that ftrains through their gills? 
But though I was at firft content to make ufe of this way of e- 
ftimating the Air concealed in water > yet when I came where I 
could be a little better accommodated with glafles , I bethought 
my felf of a fmdl Inftrument^that would much better difclofe the 
wonderful plenty of the Aerial particles I defigned to difcover* 
The ftrufture and ufe of this Gla(s may be eafily enough under- 
ftood by the recital of the firft Experiment, that was made with 
itj whereof take the following Tranfiript^ 
I We provided a clear round Glafs , farnifhed with a pipe or 
ftemof about 9 inches in length, the globulous part of the glafs 
being on the outfide about 3! inches in diameter 5 the Pipe of 
this glafs was within an inch of the top, melted at the flame of a 
Lamp, and drawn out for two or three inches as ilender as a 
j ,CrowVquill, that the decrement of the water upon thcRecelie 
of the Air, harboured in its pores, might, if any (liould happen, 
; be the more eafily obferved and eftimated» Above this {lender 
j ftjpartof the Pipe, the Glafs, as was before intimated, was of the 
! •^hmek.rgenefs (or near it) with the reft of the Pipe , that the A» 
-erial bubbles^afcending through the Qender part.might there find 
1 room to break , and fo prevent the overflowing ^ or lofs of any 
part of the water. T 2 This 
