Water-ram

or HYDRAULIC RAM. (Phys.) A machine used for raising a small quantity of water a great height by means of a water-flow below. In Fig. 679, which represents a section of Montgolfier's Hydraulic Ram, R is the reservoir from which the water falls, RS the height of the fall, and ST the horizontal tube which conducts the water to the engine ABHTC. E and D are two valves, the former of which closes its cavity by ascending, the latter by descending; and FG is a pipe reaching within a very little of the bottom CB. The valves are such that the water at its normal pre ure cannot support their weight; the valve E is prevented from falling below a certain point by a knob above mn. When the water is allowed to descend from the reservoir, after filling the tube BHS, it rushes out at the aperture mn, till its velocity in descending RST becomes so great as to force up the valve E, and close the means of escape. The water being thus suddenly checked, and unable to find a pa age at mn, will produce a great action on every part of the containing ve els, and by its impact raise the valve D. A portion of water being admitted into the ve el ABC, the impulse of the column of fluid is expended, the valves D and E fall; the opening at Dbeing thus closed, and that at mn opened. The water now rushes out at mn as before, till its motion is again stopped by its carrying up the valve E, when the operation is repeated, the fluid impulse opening the valve at D, through which a portion of the water pa es into ABC. The valves at E and D thus alternately closing and opening, and water at every opening ofD making its way into ABC, the air therein is condensed, for it has no communication with the atmosphere after the water is higher than the bottom of the pipe FG. This condensed air, then, exercises great force on the surface, P 0 ப ا ل ع H Fig. 679.-WATER-RAM. op, of the water, and raises it in the tube, FG, to a height proportioned to the elasticity of the imprisoned air. The principles of the hydraulic ram are susceptible of a very extensive application. In well-constructed rams, the mechanical effect obtained should be from 65 to 75 per cent. of the force supplied. [s. 952]