1none of the Air been drawn away from a
bout the Needle, which when the Load
ſtone was removed, after ſome tremu
lous Vibrations to and fro, reſted in a po
ſition wherein it look'd North and
South.
bout the Needle, which when the Load
ſtone was removed, after ſome tremu
lous Vibrations to and fro, reſted in a po
ſition wherein it look'd North and
South.
Experi
ment 16
ment 16
PRoceed we now to the mention of
that Experiment, whereof the ſatiſ
factory tryal was the principal Fruit I
promiſ'd my ſelf from our Engine. It
being then ſufficiently known, that, in
the Experiment De Vacuo, the Quick
ſilver in the Tube is wont to remain ele
vated, above the ſurface of that whereon
it leans, about 27 digits: I conſidered,
that, if the true and onely reaſon why the
Quick-ſilver falls no lower, be, that at
that Altitude, the Mercurial Cylinder in
the Tube, is an Æquilibrium with the
Cylinder of Air, ſuppoſ'd to reach from
the adjacent Mercury to the top of the
Atmoſphere: If this Experiment could
be try'd out of the Atmoſphere, the
Quick-ſilver in the Tube would fall
down to a levell with that in the Veſſel,
ſince then there would be no preſſure up
on the Subjacent, to reſiſt the weight of
that Experiment, whereof the ſatiſ
factory tryal was the principal Fruit I
promiſ'd my ſelf from our Engine. It
being then ſufficiently known, that, in
the Experiment De Vacuo, the Quick
ſilver in the Tube is wont to remain ele
vated, above the ſurface of that whereon
it leans, about 27 digits: I conſidered,
that, if the true and onely reaſon why the
Quick-ſilver falls no lower, be, that at
that Altitude, the Mercurial Cylinder in
the Tube, is an Æquilibrium with the
Cylinder of Air, ſuppoſ'd to reach from
the adjacent Mercury to the top of the
Atmoſphere: If this Experiment could
be try'd out of the Atmoſphere, the
Quick-ſilver in the Tube would fall
down to a levell with that in the Veſſel,
ſince then there would be no preſſure up
on the Subjacent, to reſiſt the weight of