F. ¼ G. ⅙ H. ⅛ 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, through the narrow passage of F, and denote exactly the height of the _Cylinder_ of water, then cementing in a second Pipe as G, and filling it with water; he may proceed as with the former, denoting likewise the height of the _Cylinder_ of water, able to protrude the _bubble_ C through the passage of G, the like may he do with the next _Pipe_, and the next, &c. as far as he is able: then comparing the several heights of the _Cylinders_, with the several _holes_ through which each _Cylinder_ did force the _air_ (having due regard to the _Cylinders_ of water in the small _Tubes_) it will be very easie to determine, what force is requisite to press the _Air_ into such and such _a hole_, or (to apply it to our present experiment) how much of the pressure of the _Air_ is taken off by its ingress into smaller and smaller _holes_. From the application of which to the entring of the _Air_ into the bigger _hole_ of the _Vessel_, and into the smaller _hole_ of the _Pipe_, we shall clearly find, that there is a greater pressure of the air upon the water in the _Vessel_ or greater _pipe_, then there is upon that in the lesser _pipe_: For since the pressure of the _air_ every way is found to be equal, that is, as much as is able to press up and sustain a _Cylinder_ of _Quicksilver_ of two foot and a half high, or thereabouts; And since of this pressure so many more degrees are required to force the _Air_ into a smaller then into a greater _hole_ that is full of a more congruous fluid.