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Some attribute ye cause of that effect to ye weight of ye air wch acts fully upon ye water of a large pipe, and cannot well act upon that of a narrow, but we must reject that cause: for if one plung a like pipe into mercury, it will not mount any higher than ye level of ye rest of ye mercury, and neveryeless ye weight of ye air ought to act ye same as in respect of ye water: and also if we dip into water one of ye slender pipes wch hath not but half an inch height, ye water mounts to ye top, althô ye air hath then no trouble to insinuate itself there: add to this that if ye pipe is gross or that it hath been let alone along time without weting, it contracts a certain kind of plastering that ye water cannot stick and then ye water is not elevated above ye levell altho that cause of ye default of ye air remains ye same without changing.  It is necessary therefore to explain that effect by ye same causes as elevate ye water wch is in a vessel of wood more than a line and a half towards ye brim with a small concavity, and wch joyns two drops of water one to ye other when they touch, of wch causes there hath sufficiently been spoken in ye first discourse.

[[image: drawing of a closed vessel A (upper left), B (bottom left), C (bottom right), D (top right) the top A D pierced by a pipe F H M entering and sealed at the top of the vessel at E.  Two weights sit on the top of the vessel causing it to distort the top in a concave arc A M D.  The pipe is aligned with a marker I L at a dotted line across the pipe at H.]]

A surprising effect of ye equilibrium is seen in ye following experiment.  Take a vessel of wood of two or three feet long A B C D full of water: make a hole in ye top as in E thro which put a pipe of an inch large, joyned well with pitch and flax or some other matter, that ye air may not enter, and that ye streight pipe, viz E F is 12 or 15 feet high: fill ye vessel with water thro some holes in ye top, and place upon ye top 700 or 800 pound weight that it may bend it concave as A M D if you put a white mark to ye side of of ye pipe as at H, and a little heigher a rule I L fixed in ye neighboring wall and fastened so that it may remain immoveable, by pouring ye water by little and little into ye pipe E F, you shall see that when it is full ye end A M B will be elevated with ye weight of 800