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90.

  When there is a great reservatory as of a foot on ye top of a pipe of 50 or 60 foot heigh and of three inches large;  it happens that making a spout of 9 or 10 lines it doth not mount so heigh as it ought in proportion to the height of ye reservatory;  for ye water of ye reservatory cannot come so swift from ye sides wch are far off from ye hole to enter into ye pipe, and it ordinarily makes a kind of whirlpool because of ye too great expence of ye water wch is made thrô ye passage joyned to ye rubbing in ye pipe as hath been explained formerly.  Whence there follows an effect sufficiently surprizing wch is that when ye spout a first goeth to a height as of 45 feet it deminisheth and goeth but to 44 feet and afterwards it remounts to 46 or 47, wch arrives as soon as ye air can enter thrô ye hole of ye vessel:  For then besides ye acceleration of ye water wch goeth swifter ye height of ye spout is made according to ye height of ye water from ye bottom of ye vessel, and is not hindered by ye superior water this reason is confirmed by the following experiment.

[[image:  three dimensional drqwing of an L-shaped vessel with a large vertical diameter A B C and a smaller base C D, a small opening at D. There is a horizontal diameter line A B across the dotted line circumference of the top of the vessel.  About 1/3 of the way down the vessel there is a dotted circumference line E F and an internal tube G M N beginning at this point down to the base of the "L."  Below F there are markers K I N O.]]

 There was made a reservatory of 6 foot heigh as A B C D and at a foot below ye heighest place we soddered a plate within represented by E F pierced with an hole of 8 lines diameter in G.  We poured water till it began to run thrô ye hole D, and stopped that hole filling up ye reservatory  To do it ye sooner we must make a small hole below F as in K, that ye water entering into ye reservatory through the hole G ye air may go out easier, and stop it afterwards when ye pipe shall be full to E F to fill up ye reservatory to A B.  This reservatory being full, we permitted ye hole D to run and ye sout mounted at ye beginning to J and diminished by little and little till it was below ye plate;  for then ye water was elevated unto K.

  The cause of this effect is ye same as that of ye great running out of ye water when we put a small pipe at ye hole of a large reservatory  For then ye water runs thrô ye cylinder of water G L M D, in like manner as if it was a pipe ye rest of ye water having no considerable motion because of ye plate.  But when ye water is below G and that ye air begins to pass there, all ye water E F M is free to act upon D, and it ought to spout very near to F.  Ye effect shall be yet more strange if ye hole D is 6 or 7 lines and ye hole G 3 or 4;  for ye spout will go at first no heighter than O N and will decrease to O, and ye water being below G it will remount almost to F.

Transcription Notes:
mandc: Reviewed. Changed "Fir tgeb besudes te" to "For then besides ye."