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49.

[[image:  drawing of spherical cylinder closed at the bottom, open at the top (A) with a male figure inside and labeled A (top), D (left side of figure), E (right side of figure)), C (just below figure), F (just below C), B (just below F), G (just below B)]]

we make a little water enter into ye figure by ye small hole D, wch makes that ye specific gravity is then more than that of water, and it descends:  but when than that of of water, and it descends:  but when we take away away ye finger, ye inclosed air presseth back ye water by ye same hole by virtue of its spring wch is get at liberty and regaining [[strikethrough]] regaining its disposition and remounts, but if [[/strikethrough]] its dilation ye figure with ye water and inclosed air, regains its first disposition and remounts.  But if we take away ye finger swiftly, a small part of ye air will go out suddenly with ye water by ye small hole, and both will make by its shoc against ye water of ye pipe [[?(piroiietter)]] [[space]] ye figure.  It happens sometimes that there goeth much air out of ye figure and that being at ye bottom it [[srikethrough]] must [[/strikethrough]] cannot remount althô we have taken away ye finger, then it is necessary to plunge ye finger deep into ye vessel and retire it so that it exactly fill ye channel, so that no exterior air can enter ye place of ye finger;  and it will happen that ye air of ye figure being then much less pressed dilates it thrô ye small figure;  wch renders it lighter and will make it remount on heigh, provided that we always keep ye finger in ye pipe without taking it entirely out:  sometimes ye weight of ye figure and ye inclosed air is so full proportioned to ye specific weight of ye water that by putting ye finger in A ye remount;  but if we make it descend unto B and take away ye finger, it finisheth its descent;  wch proceeds from hence ye ye weight of ye water A C doth not press enough of ye air of ye small figure to make sufficient water enter to render its specific weight equall to that of water, and that ye weight of ye water A B presses sufficiently for that effect, wch makes it descend to ye bottom where ye weight of ye water being yet greater, condenses ye air of ye small figure more than before, and makes a little more water enter:  whence it happens that we have more trouble to make it remount, where may be seen ye error of those wch believe that ye water and ye air do not gravitate upon ye bodys ye bodys wch are below, and they judge so because we do not feel ye weight of ye air;  but we must consider that our bodys is disposed naturally for such a pressure of ye air as it is below;  and therefore do not sustain any incommodity.  But if we were transported into an air twice as much rarefied, ye aerine matter wch should be in our blood and in ye other parts of our bodys wch are very hot, would return into air and would cause bubling out wch would puff up our body and we should be very uneasy.  We see an experiment when we inclose a bird in ye wind pump, for when ye air is reduced to a double or triple dilatation to that wch is near ye earth, ye bird dies in a short times because that its blood being no more pressed by ye ordinary spring of ye air, cast out quantity of bubbles like hot water when inclosed in ye same time:  but if on ye contrary we were in an air doubly condensed, we might suffer much althô we were at some trouble to rescent its pressure;  because if of one side it should press ye breast to hinder respiration on ye other side ye air wch should enter there by respiration [[?having]] a spring would hinder ye action of ye exterior air:  whence it follows that those wch go 7 or 8 feet under water ought not to perceive any sensable weight, because they are equally pressed one all sides and that ye weight of ye atmosphere being equall to ye weight of 32 feet of water, these 8 feet added do not augment ye pressure but about 1/5 wch cannot be very sensable.  Some object against these reasons and these effects of ye spring of ye air, that when a pipe is perfected at both ends to make ye experiments of ye inclosed air, [[strikethrough]] that when a pipe [[/strikethrough]] above ye mercury if we stop ye upper end with ones finger to hinder ye communication of ye air with that wch is inclosed, it happens that when ye experiment is made there seems to him who stops ye upper end, that his finger is as it were drawn and sucked by ye mercury wch descends, and also he feels pain like pinching whence they conclude that ye dilated air in ye pipe doth not make an effort to sustain one part of ye air of ye atmosphere since it would push against ye finger and push it back rather than draw it.  To satisfie this difficulty we must consider that when we inclose some bodys as a [[?wrinckld]] apple in ye wine pump and have pumped out a good part of ye inclosed air, these bodys puff up and dilate themselves and that if we had inclosed ye half of ones finger by ye means