Hydrostatics and pneumatics / [Dionysius Lardner].

  • Dionysius Lardner
Date:
1831
Catalogue details

Licence: Public Domain Mark

Credit: Hydrostatics and pneumatics / [Dionysius Lardner]. Source: Wellcome Collection.

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    becomes sufficiently rarefied by this process, the atmo- spheric pressure forces water from the well through the suction pipe and the valve V into the chamber between the piston and the valves. When the piston now de- scends, it presses on the surface of the water, and the valve V opening upwards prevents the return of the water into the suction pipe; while the pressure of the piston, being transmitted by the water to the valve V7, opens it, and, as the piston descends, the water passes into the force pipe G H. The next ascent of the piston allows more water to pass through the valve V, and the next descent forces this water through the valve V7 into the force pipe. By continuing this process, the quantity of water in the force pipe continually increases, receiving equal additions at each descent of the piston. It is evident that the force pipe may be placed in any position, whether perpendicularly, obliquely, or hori- zontally, and that, in every case, the action of the piston will propel the water through it. When the piston is pressed downwards, and the valve V' is opened, it is necessary that the force which works the piston should balance the weight of the column of water in the force pipe, for this weight is transmitted by the water between the piston and force pipe to the bottom of the piston; consequently,'the height of the column of water in the force pipe will measure the in- tensity of the pressure against the base of the piston when the valve V/ is open. A column of water about 34 feet in height, suspended in the force pipe, will press on the base of the piston with a force of about 15 pounds on each square inch, and the pressure at other heights will be proportional to this. The force neces- sary to urge the piston downwards may, therefore, al- ways be calculated. In drawing the piston up the valve V7 is closed, and relieves the piston from the weight of the incumbent column ; if the valve V is opened, the piston is subject to the same pressure as in the suction pump. This pressure has been already proved to be Y