This Experiment is much of the ſame
nature with that which was ſome years
agoe ſaid to be made by that eminent Ge
ometrician Monſieur Roberval, with a
Carps Bladder empty'd and convey'd into
a Tube, wherein the Experiment De Va
cuo was afterwards try'd, which ingeni
ous Experiment of his juſtly deſerves the
thanks of thoſe that have been, or ſhall be
ſolicitous to diſcover the nature of the
Air.
nature with that which was ſome years
agoe ſaid to be made by that eminent Ge
ometrician Monſieur Roberval, with a
Carps Bladder empty'd and convey'd into
a Tube, wherein the Experiment De Va
cuo was afterwards try'd, which ingeni
ous Experiment of his juſtly deſerves the
thanks of thoſe that have been, or ſhall be
ſolicitous to diſcover the nature of the
Air.
But to return to our Experiment, we
may take notice of this Circumſtance in
it, That after the Receiver has been in
ſome meaſure empty'd, the Bladder do's,
at each exſuction, ſwell much more con
ſpicuouſly then it did at any of the firſt
Exſuctions; inſomuch that towards the
end of the pumping, not onely a great
fold or cavity in the ſurface of the Blad
der may be made, even by the ſtretching
of the inward ſelf-expanding Air: But
we have ſometimes ſeen, upon the turn
ing of the Key to let the ambient Air
paſs out of the Receiver into the Cylin
der, we have ſeen (I ſay) the Air in the
Bladder ſuddenly expand it ſelf ſo much
and ſo briskly, that it manifeſtly lifted up
ſome light Bodies that lean'd upon it,
may take notice of this Circumſtance in
it, That after the Receiver has been in
ſome meaſure empty'd, the Bladder do's,
at each exſuction, ſwell much more con
ſpicuouſly then it did at any of the firſt
Exſuctions; inſomuch that towards the
end of the pumping, not onely a great
fold or cavity in the ſurface of the Blad
der may be made, even by the ſtretching
of the inward ſelf-expanding Air: But
we have ſometimes ſeen, upon the turn
ing of the Key to let the ambient Air
paſs out of the Receiver into the Cylin
der, we have ſeen (I ſay) the Air in the
Bladder ſuddenly expand it ſelf ſo much
and ſo briskly, that it manifeſtly lifted up
ſome light Bodies that lean'd upon it,