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79.
A Table of the Expence
of water in one minute through different
round ajutages [[space]] the water of ye
reservatory being
13 foot heigh.
Diameters | Expence
Thrô a passage of 1 line | 1 pint 10/18
Thrô 2 lines | 6 pints 2/9
Thrô 3 lines | 14 pints
{ 4 lines | almost 25 pints
{ 5 lines | 39 pints
{ 6 lines | 56 pints
Thrô 7 lines | 76 1/4
{ 8 lines | 110 2/3
{ 9 lines | 126
{ 12 lines | 224 pints
If we would observe ye calculation of inches we shall find that a hole of 3 lines will give an inch that of 6 lines 4 inches, and that of 12 lines 16 inches.
There is some causes wch hinder ye exactness of these rules, so that very often great holes give a little more in proportion than ye small ones and sometimes a little more than according to a subduple proportion and sometimes a little less. I have made ye following experiments.
Experiment III
I took a pipe of half a foot diameter and about 6 feet heigh having a reservatory at ye top wch did contain about 12 pints; I put at ye bottom ye same plate pearced with an hole of 12 lines wch served ye first experiments, and another of 4 lines in ye same bottom; ye hole of 12 lines was distant about an inch from ye edge of ye base, and that of 4 lines also an inch, we put a great vessel below wch had a seperation wch divided it unequally, it was filled so that ye water wch run thrô ye 4 lines might enter into ye small separation and that wch run thrô ye inch in ye other ye pipe being full ye 2 holes were permitted to run at ye same time, and ye vessel was drawn away on a sudden, so that ye two holes might cease to run sensibly at ye same moment, we always found that ye great hole wch according to ye second rule ought to give 9 times as much as the small gave but 8 times as much, and 8 times and a little more in other experiments. Ye cause of this effect is ye same as we have spoken above, viz ye water runs not so easily thrô ye great hole as thrô ye small; for ye great one being to give 9 times as much water it is necessary that wch should succeed what comes should come from near a foot circumference, and ye distance on one side of ye pipe was but an inch and ye further distance 4 inches; wch would retard ye running, ye superior water not being able to come so swift as was necessary; whereas in ye small hole ye distance of an inch on all sides was sufficient to furnish swiftness enough for ye running; and that difference made 1/2 difference in ye quantity of ye water un out, as in ye experiment of an inch where ye center was lower than ye surface of ye water 7 lines wch gave but 13 3/8 pints whereas ye hole of 6 lines gave 1/4, or 15 pints its center being ye same distance of 7 lines from ye upper surface of ye water.
Experiment IV
To take away this difficulty of ye running many experiments were made in a tub whose bottom was large enough to place ye hole of 12 lines a foot from ye nearest side, and ye small hole was placed more than a foot distance from ye great one. Ye experiment being made with ye same vessel where there was a separation we always found that ye great hole gave less than 9 times ye small one, for it wanted sometimes 1/18, and sometimes 20,
Transcription Notes:
mandc: Reviewed. Ajutages is spout in French.
