1a Quart; but that (agreeably to what we
formerly obſerved) we found it as difficult
to bring this to be quite empty as to eva
cuate the greater; the leaſt external Air
that could get in (and we could not poſſi
bly keep it all perfectly out) ſufficing in ſo
ſmall a Veſſel to diſplay a conſiderable
preſſure upon the ſurface of the Mercury,
and thereby hinder that in the Tube from
falling to a level with it. But this is remark
able, that having two or three times try'd
the Experiment in that ſmall Veſſel, upon
the very firſt Cylinder of Air that was
drawn out of the Receiver, the Mercury
fell in the Tube 18 Inches and a half, and
at another 19 Inches and a half.
formerly obſerved) we found it as difficult
to bring this to be quite empty as to eva
cuate the greater; the leaſt external Air
that could get in (and we could not poſſi
bly keep it all perfectly out) ſufficing in ſo
ſmall a Veſſel to diſplay a conſiderable
preſſure upon the ſurface of the Mercury,
and thereby hinder that in the Tube from
falling to a level with it. But this is remark
able, that having two or three times try'd
the Experiment in that ſmall Veſſel, upon
the very firſt Cylinder of Air that was
drawn out of the Receiver, the Mercury
fell in the Tube 18 Inches and a half, and
at another 19 Inches and a half.
But, on this occaſion, I hold it not un
fit to give Your Lordſhip notice that I
hop'd, from the deſcent of the Quick
ſilver in the Tube upon the firſt ſuck, to
derive this advantage: that I ſhould thence
be enabled to give a near gueſs at the pro
portion of force betwixt the preſſure of
the Air (according to its various ſtates, as
to Denſity and Rarefaction) and the gra
vity of Quick-ſilver, then hitherto has
been done. For in our Experiment there
are diverſe things given, that may be
made uſe of towards ſuch a diſcovery.
fit to give Your Lordſhip notice that I
hop'd, from the deſcent of the Quick
ſilver in the Tube upon the firſt ſuck, to
derive this advantage: that I ſhould thence
be enabled to give a near gueſs at the pro
portion of force betwixt the preſſure of
the Air (according to its various ſtates, as
to Denſity and Rarefaction) and the gra
vity of Quick-ſilver, then hitherto has
been done. For in our Experiment there
are diverſe things given, that may be
made uſe of towards ſuch a diſcovery.