1of it: Then the Receiver muſt be taken
off from the Pump, that the upper Ori
fice of the Cylinder remaining open, the
Air may freely ſucceed the Sucker, and
therefore readily yield to its motion
downward. This done, there muſt be
faſten'd to one of the Iron Teeth of the
Sucker, ſuch a weight as may juſt ſuffice
to draw it to the bottom of the Cylinder.
And having thus examin'd what weight is
neceſſary to draw down the Sucker, when
the Atmoſphere makes no other then the
ordinary reſiſtance of the Air againſt its
deſcent; the Sucker muſt be again forc'd
to the top of the Cylinder, whoſe upper
Orifice muſt now be exactly cloſed; and
then (the firſt weight remaining) we eaſi
ly may, by hanging a Scale to the above
mention'd Iron (that makes part of the
Sucker) caſt in known weights ſo long,
till in ſpight of the reluctancy of the At
moſphere the Sucker be drawn down. For
to theſe weights in the Scale, that of the
Scale it ſelf being added, the ſum will give
us the weight of a Column of Air, equal
in Diameter to the Sucker, or to the ca
vity of the Cylinder; and in length to
the heighth of the Atmoſphere.
off from the Pump, that the upper Ori
fice of the Cylinder remaining open, the
Air may freely ſucceed the Sucker, and
therefore readily yield to its motion
downward. This done, there muſt be
faſten'd to one of the Iron Teeth of the
Sucker, ſuch a weight as may juſt ſuffice
to draw it to the bottom of the Cylinder.
And having thus examin'd what weight is
neceſſary to draw down the Sucker, when
the Atmoſphere makes no other then the
ordinary reſiſtance of the Air againſt its
deſcent; the Sucker muſt be again forc'd
to the top of the Cylinder, whoſe upper
Orifice muſt now be exactly cloſed; and
then (the firſt weight remaining) we eaſi
ly may, by hanging a Scale to the above
mention'd Iron (that makes part of the
Sucker) caſt in known weights ſo long,
till in ſpight of the reluctancy of the At
moſphere the Sucker be drawn down. For
to theſe weights in the Scale, that of the
Scale it ſelf being added, the ſum will give
us the weight of a Column of Air, equal
in Diameter to the Sucker, or to the ca
vity of the Cylinder; and in length to
the heighth of the Atmoſphere.
Experi
ment 33.
ment 33.
According to this method we did, ſince