HYDRAULIC RAM, or WATER RAM. An ingenious hydraulic machine for raising water by means of its own impulse. The principle of its action and the mechanism of its construction may he described as follows The water arriving at A from the re servoir with the due to the height of the fall, passes along the pipe A B, which should have an inclination of at least an inch for every two yards, escapes through an orifice C, which may be shut at pleasure by means of a valve. A reservoir, F, filled with air, is attached by means of a cylinder, a b c d, to the pipe A B D; in the middle of the bottom of the reservoir F is a circular orifice, to which there is adapted a short cylindri cal tube, of which the extremity E is also furnished with a valve. Another valve, S, serves to supply the air to the space comprised between the cylinder abed and the tube E. G I H is an as censional tube rising from the reservoir F. The water which escapes at C is car ried off by the waste pipe K L.
The form of this apparatus (or perhaps its mode of action) suggested the name it has received. The pipe A B C is called the body if the ram; and the extremity, where the valves and the reservoir F are placed, is called its head. Both valves D and E are formed of hollow balls sup ported on muzzles, and of such a thick ness of metal that they weigh about twice as much as the quantity of water they displace.
We may now consider the effects of the engine when in action. The water, flowing through the orifice G, acquires the velocity due to the height of the full, and raises the ball D from its support till it comes to the orifice C ; the extremity of this orifice is covered with leather, or with cloth filled with pitch, so that when the ball is applied to it, the passage of the water is effectually prevented. As soon as this orifice is closed, the water raises the ball E which had shut the ori fice of the reservoir F, and a portion of it introduces itself into this reservoir, and into the pipe G I H. It thus loses the velocity which it had when the ori fice C was shut, and the balls D and E fall down in consequence, the one on its support, and the other on the orifice at E.
support, this takes place, every thing is in the same state in which it was at first. The water begins again to flow through the orifice C; the valve D is again shut ; and the same effects are re peated in an interval of time, which, for the same ram, undergoes little variation.
Every time the impulse is renewed, a quantity of water is forced up into the reservoir F and the tube H; and as it is prevented from returning by the action of the valve, it must necessarily be deli vered at the extremity of H. The use of the air-vessel F is to keep up a continu ous motion of the ascending column of water. The communication with the ex ternal atmosphere being cut off, the air within F is compressed by a force pro portional to the height of the surface of the water in H above its surface in F; and this compressed air, acting by its elasticity on the water, maintains a con tinuous flow through H. The air-vessel, however, though it assists the action of the ram, is not an essential part of it; the continuity of the discharge of water may be effected by means of two or more rams, of which the ascensional pipes G H all terminate in a single branch. On this principle works have been erected at Manly, in France, which raise water in a continuous jet to the height of 57 metres, or 187 English feet.
As the ascending column of water com municates with the air in the reservoir F, this would soon be exhausted if a fresh portion of air were not introduced at each stroke of the ram. The little tube S, which is stopped by a valve opening inwards, serves for this purpose. At the instant when the orifice C is closed a re coil takes place, by which the water is thrown back from the head of the ram to wards the cistern ; and a partial vacuum being thus produced within the cylinder a b c d, the pressure of the external at mosphere forces open the valve in the canal S, and a portion of ,air enters the cylinder, whence it is driven into the re servoir, excepting the small part of it which lodges in the space between the cylinder abed and the tube E.
The invention of the hydraulic ram, at least in the improved form here de scribed, belongs to Montgolfier, of Mont pelier. A machine, however, on the same principle had previously becu sug gested, and even erected at Chester (Eng.), by Mr. Whitehurst, but much less perfect in its mode of action ; for the orifice C, instead of being opened and shut by the action of the water itself, required to be opened and shut by the hand by means of a stop-cock. Owing to this circum stance, Whitehurst's machine was of lit tle utility, and appears to have soon been entirely forgotten.