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29.

to ye top of ye surface of ye water wch is below ye neck of ye bottle; if we incline ye bottle so that ye point L and ye middle of ye overturn C may be in ye same horizontal line, we shall see part of a drop of air wch will pass below from ye point L but wch will not be seperated from ye rest if we do not raise ye end L a little upright.

  When ye air is permitted to enter into ye bottle so that ye surface of ye water may be in n o and that air is heated with ones hand to make it be dilated there goeth out some drops of water thrô although ye end of ye pipe should be below that overture, and ye water will descend to P Q but if ye air is permitted to cool, we shall see during some time drops of air enter through C because that ye air wch was descended unto P Q returns into its former extent from n o unto A H, and having not enough water to fill ye space n o P Q, it is necessary that ye air should come thither from without thrô ye overture C.

  The water hath not any sensable spring and makes an equilibrium with other matter only by its weight or by its shock, ye of other equilibrium that may be observed in respect of ye air, is that being reduced to very small drops, it becomes higher than ye air, and is elevated in vapours as hath been said before.  It cannot be said how small a parcel of water ought to be to make an equilibrium with ye air near ye earth, because those wch are a little heavier or a little  higher than that air are separately invisable.  It is also hard to find ye cause if their elevation, for it is not mixture of ye air since they should weigh yet more than ye pure air; it is not ye heat, because very cold water is found to cast out vapors.  It may be supposed that there is small pores in ye air, where there is not any heavy matter, into wch ye small parcels of water may insinuate and mount that way, and those wch are a little grosser cannot pass.  These small parcell make at last an equilibrium with ye air, at ye distance of a league or 2 from ye earth, and they remain there a long time suspended until many being joined together become heavier, and it ye should be very much raryfied they might fall.

  There is seen an experiment in ye pneumachic engines; for when on part of ye air is pumped, ye recipient is seen troubled by ye fall of vapours wch cannot be any longer sustained in ye air, because of ye two great rarefacation, falling in small drops upon ye glass that encompasses them.  in ye places where this is great falls of water, there is seen vapours to be perpetually elevated wch are nothing else but parcells of water broken by ye shock; and when a bubble of soap come to be broken, on part if ye water of wch it is compossed, falls, and ye rest wch is reduced into very small drops, is elevated as vapours.

  Rule I

  For ye equilibrium of water by its weight water being in a vessell or in many wch communicate one with hath always its [[strikethough]]?[[?strikethrough]] upper parts in ye same level; that is to say, in equal distance from ye centre of ye Earth.

  Explication.

Let ye crooked pipe A B C of an equal thickness, in wch water is poured through ye neck A,

[[image: drawing of a continuous "U" shaped tube open at the top, upper left opening labeled A, and upper right opening labeled C.  The bottom of the "U" is labeled G (left corner]], B (middle bottom), and H (right corner).  There are three levels of liquid indicated in the two arms of the tube by dotted lines: D E; I F; and N O.  A little way down from O is a marker labeled M.]]

it will mount as high in ye other pipe; that is to say that if D E is Horizontal line, and that ye water in ye branch A G mounts unto D it shall be in ye pipe in E, when we have ceased to pour, and that ye water shall remain in repose. for first if ye branches are equally large and equally inclined to ye Horizon, all being equal on both sides ye water cannot remain in ye equal hights A F, because that ye weight of ye water A shall be greater than that of ye water H F; and by consequence in descending it can take a greater quantity of motion that it can give to ye other in mounting, since their swiftness will equal and their directions like. whence by ye universal principal, ye water cannot be stopped if it is not ate ye same hight in these two branches.  but if one stop with ones finger ye end C before ye water is poured in by ye end H, and we fill with water ye branch A G unto H, ye other will remain void and there will none or very little water rise because of ye air wch possesseth it, if ye branch A G is not but two or three feet high; then if one take away ye finger ye water of ye branch A G

Transcription Notes:
mandc: "overture" is French for aperture. A clearer drawing of the image can be found here (Fig. 15): http://echo.mpiwg-berlin.mpg.de/ECHOdocuView?url=/permanent/library/QERNH1MN/pageimg&start=11&pn=99&mode=imagepath Capital "D" looks like a lower case "b" in this script. I believe there are some lapses in the translator's translation. "Swiftness" for example, here and elsewhere in this work, is used where "force" "pressure" or "velocity" are probably the words intended by the French original.