_cylindrical_ cavities: as let _hollow_ of

F. 1/4
G. 1/6
H. 1/8
I. be 1/12 of an inch.
K. 1/16
L. 1/24
M. 1/32
&c----
There may be added as many more, as the Experimenter shall think fit, with
holes continually decreasing by known quantities, so far as his senses are
able to help him; I say, so far, because there may be made _Pipes_ so small
that it will be impossible to perceive the _perforation_ with ones naked
eye, though by the help of a _Microscope_, it may easily enough be
perceived: Nay, I have made a _Pipe_ perforated from end to end, so small,
that with my naked eye I could very hardly see the body of it, insomuch
that I have been able to knit it up into a knot without breaking: And more
accurately examining one with my _Microscope_, I found it not so big as a
sixteenth part of one of the smaller hairs of my head which was of the
smaller and finer sort of hair, so that sixteen of these _Pipes_ bound
faggot-wise together, would but have equalized one single hair; how small
therefore must its _perforation_ be? It appearing to me through the
_Microscope_ to be a proportionably _thick-sided Pipe_.

To proceed then, for the trial of the Experiment, the Experimenter must
place the _Tube_ AB, perpendicular, and fill the _Pipe_ F (cemented into
the hole E) with water, but leave the _bubble_ C full of _Air_, and then
gently pouring in water into the Pipe AB, he must observe diligently how
high the water will rise in it before it protrude the _bubble_ of Air C,