1the writing of the laſt Experiment, at
tempt to meaſure the preſſure of the At
moſphere, but found it more difficult then
we expected, to perform it with any ac
curateneſs; for though by the help of the
Manubrium the Sucker moved up and
down with ſo much eaſe, that one would
have thought that both its convex ſurface,
and the concave one of the Cylinder were
exquiſitely ſmooth, & as it were ſlippery;
yet when the Sucker came to be moved
onely with a dead weight or preſſure (that
was not (like the force of him that
pump'd) intended as occaſion required)
we found that the little rufneſſes, or other
inequalities, and perhaps too, the unequal
preſſure of the Leather againſt the cavity
of the Cylinder, were able now and then
to put a ſtop to the deſcent or aſcent of
the Sucker, though a very little external
help would eaſily ſurmount that impedi
ment; and then the Sucker would, for a
while, continue its formerly interrupted
motion, though that aſſiſtance were with
drawn. But this diſcouragement did not
deterre us from proſecuting our Experi
ment, and endeavoring, by a careful trial,
to make it as inſtructive as we could.
We found then that a Leaden Weight,
tempt to meaſure the preſſure of the At
moſphere, but found it more difficult then
we expected, to perform it with any ac
curateneſs; for though by the help of the
Manubrium the Sucker moved up and
down with ſo much eaſe, that one would
have thought that both its convex ſurface,
and the concave one of the Cylinder were
exquiſitely ſmooth, & as it were ſlippery;
yet when the Sucker came to be moved
onely with a dead weight or preſſure (that
was not (like the force of him that
pump'd) intended as occaſion required)
we found that the little rufneſſes, or other
inequalities, and perhaps too, the unequal
preſſure of the Leather againſt the cavity
of the Cylinder, were able now and then
to put a ſtop to the deſcent or aſcent of
the Sucker, though a very little external
help would eaſily ſurmount that impedi
ment; and then the Sucker would, for a
while, continue its formerly interrupted
motion, though that aſſiſtance were with
drawn. But this diſcouragement did not
deterre us from proſecuting our Experi
ment, and endeavoring, by a careful trial,
to make it as inſtructive as we could.
We found then that a Leaden Weight,