1of the Valve, and forcing up of the Suck
er to the top of the Cylinder again, be
driven out into the open Air. And thus
by the repetition of the motion of the
Sucker upward and downward, and by op
portunely turning the Key, and ſtopping
the Valve, as occaſion requires, more or
leſs Air may be ſuck'd out of the Recei
ver, according to the exigency of the Ex
periment, and the intention of him that
makes it.
er to the top of the Cylinder again, be
driven out into the open Air. And thus
by the repetition of the motion of the
Sucker upward and downward, and by op
portunely turning the Key, and ſtopping
the Valve, as occaſion requires, more or
leſs Air may be ſuck'd out of the Recei
ver, according to the exigency of the Ex
periment, and the intention of him that
makes it.
Your Lordſhip will, perhaps, think that
I have been unneceſſarily prolix in this
firſt part of my Diſcourſe: But if you
had ſeen how many unexpected difficul
ties we found to keep out the externall
Air, even for a little while, when ſome
conſiderable part of the internal had been
ſuckt out; You would peradventure al
low, that I might have ſet down more
circumſtances then I have, without ſet
ting down any, whoſe knowledge, he that
ſhall try the Experiment may not have
need of. Which is ſo true, that, before we
proceed any further, I cannot think it un
ſeaſonable to advertiſe Your Lordſhip,
that there are two chief ſorts of Experi
ments, which we deſign'd in our Engine
to make tryal of: The one, ſuch as may
I have been unneceſſarily prolix in this
firſt part of my Diſcourſe: But if you
had ſeen how many unexpected difficul
ties we found to keep out the externall
Air, even for a little while, when ſome
conſiderable part of the internal had been
ſuckt out; You would peradventure al
low, that I might have ſet down more
circumſtances then I have, without ſet
ting down any, whoſe knowledge, he that
ſhall try the Experiment may not have
need of. Which is ſo true, that, before we
proceed any further, I cannot think it un
ſeaſonable to advertiſe Your Lordſhip,
that there are two chief ſorts of Experi
ments, which we deſign'd in our Engine
to make tryal of: The one, ſuch as may
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