1but for a great while we ſcarce ſaw one
bubble appear, onely when the Receiver
had been very much exhauſted, and the
Water was fallen very low, there appear'd
near the bottom of the Tube, certain
little bubbles, which ſeem'd to conſiſt of
ſuch parcels of Air as had not, by reaſon
of their ſmalneſs, got up to the top of
the Water, with the more bulkie and vi
gorous ones. And that which is not in
conſiderable, is, That having, by letting
in the Air, forc'd up the Water into the
Tube, we could not perceive that it aſ
cended nearer the top, though we per
mitted the Engine to remain unimploy'd
for two or three Nights together, and
watch'd whether the Water would ſwell
up and fill the Tube. And on this occa
ſion I remember, that having try'd ſuch an
Experiment as this with Quick-ſilver in
ſtead of Water, in a Tube of about a Foot
and a half long, wherein it might ſeem
more hopeful to eſcape bubbles; yet up
on the drawing down the Quick-ſilver as
low as we could, and letting in the exter
nal Air upon it, we found that ſome lurk
ing particles of Air were got up to the top
of the Tube, and hinder'd the Quick
ſilver from being forc'd up again ſo high.
bubble appear, onely when the Receiver
had been very much exhauſted, and the
Water was fallen very low, there appear'd
near the bottom of the Tube, certain
little bubbles, which ſeem'd to conſiſt of
ſuch parcels of Air as had not, by reaſon
of their ſmalneſs, got up to the top of
the Water, with the more bulkie and vi
gorous ones. And that which is not in
conſiderable, is, That having, by letting
in the Air, forc'd up the Water into the
Tube, we could not perceive that it aſ
cended nearer the top, though we per
mitted the Engine to remain unimploy'd
for two or three Nights together, and
watch'd whether the Water would ſwell
up and fill the Tube. And on this occa
ſion I remember, that having try'd ſuch an
Experiment as this with Quick-ſilver in
ſtead of Water, in a Tube of about a Foot
and a half long, wherein it might ſeem
more hopeful to eſcape bubbles; yet up
on the drawing down the Quick-ſilver as
low as we could, and letting in the exter
nal Air upon it, we found that ſome lurk
ing particles of Air were got up to the top
of the Tube, and hinder'd the Quick
ſilver from being forc'd up again ſo high.
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