77

Of Hydraulk Engines .

and then begins to condense the air in the vessel KK. For, as thepipe G H is fixed air-tight into the vessel below F, and the air has noway to get out of the vessel but through the mouth of the pipe at I, andcannot get out when the mouth I is covered with water, and is moreand more Condensed as the water rifes upon the pipe, the air then be-gins to act forcibly by its spring against the furface of the water at H:and this action drives the water up through the pipe IHGF, fromwhence it fpouts in a jet 5 to a great height; and is fupplied by alter-nately raising and depressing of the plunger g, which constantly forcesthe water that it raifes through the valve H t along the pipe MM rinto the air-vessel KK.

The higher that the furface of the water H is raifed in the air-vessel,the lefs fpace will the air be Condensed into, which before filled thatvessel; and therefore the force of its spring will be so much the strongerupon the water, and will drive it with the greater force through thepipe at F: and as the spring of the air continues whilst the plunger^is rising, the stream or jet S will be uniform, as long as the action ofthe plunger continues: and when the valve b opens, to let the waterfollow the plunger upward, the valve a ffiuts, to hinder the water,which is forced into the air-vessel, from running back by the pipeMM into the barrel of the pump.

If there was no air-vestel to this engine, the pipe G/ffwould bejoined to the pipe MMN at Pj and then, the jet S vvould stop everytime the plunger is raifed, and run only when the plunger is depressed,

Mr. Newfham ’s water-engine, for extinguiffiing sire, confists of twoforcing-pumps, which alternately drive water into a clofe vtssel of air $and by forcing the water into that vessel, the air in it is thereby Con-densed, and compresses the water so strongly, that it rufhes out withgreat impetuosity and force through a pipe that comes down into it;and makes a continued uniform stream by the condenfation of the airupon its furface in the vestel.

By means of forcing-pumps, water may be raifed to any heightabove the level of a river or spring ; and machines may be contrivedto work these pumps, either by a running stream, a fall of water, orby horses. An instance in each fort will be sufficient to Ihew the me-thod.

First, by a running stream, or a fall of water. Let be a wheel, pi ate xii,iurned by the fall of water BB-, and have any number of cranks p ig- «•(suppofe six) as G,D } E,F,G,H, on its axis, according to the strengthof the fall of water, and the height to which the water is intended tobe raifed by the engine. As the wheel turns round, these cranks move

the