NOTE.—In 1797 Matthew Boulton (manufacturer and practical engineer, and in later life a partner of Jas. Watt, the Father of the steam engine) obtained a patent for a mode of raising water by impulse. The apparatus had excited much attention in France, under the name of _Montgolfier’s hydraulic ram_, and Boulton added to it a number of ingenious modifications, which were the basis of his patent.
Fig. 150 shows in section the construction of the ram in its simplest form in which E is the reservoir, A the pipe in which the water falls, B the channel, _a_ and _b_ the valves, C the air-chamber, and D the discharge. Water first flows out in quantity through the valve _a_, and as soon as it has acquired a certain velocity it raises that valve, closing the aperture. The impact thus produced, acting on the sides of the pipe and the valve _b_, raises this valve, and a quantity of water passes into the air-chamber shutting off air and compressing it in the space above the mouth _d_ of the discharge D. This air by its electric force closes the valve _b_, and the water which has entered is raised in the discharge D.
As soon as the impulsive action is over, and the water in the channel A comes to rest, the valve _a_ again falls by its own weight, the flow begins afresh, and when it has acquired sufficient velocity the valve _b_ again closes, and the whole process is repeated.
_The efficiency of hydraulic rams_ has been much discussed; exhaustive practical tests have been made and the results have been reduced to formulas. Whittaker’s Mechanical Engineer’s Pocket Book gives the following:
where E = the efficiency; G = gallons of drive water used; g = gallons of water raised; H = height of fall, in feet; h = height to which the water is raised, in feet.
_The Table_ given on page 174 is from the _American Engineer_. Its use is apparent, thus: when the height of fall in feet is, say 12 feet, and the elevation of discharge above the delivery valve of ram, in feet, is 30 feet, _the efficiency_ or per cent., is ·3282. (_Example_) of 100 gallons 32-82/100 gallons would be delivered.
_The double hydraulic ram_ is shown in Fig. 151. A sectional view of the same device is shown in Fig. 152, the cuts represent the Rife hydraulic engine, or ram,—a so-called double acting or double supply type of the water ram. It is more clearly described by considering it, first, as a single machine by disregarding its double supply feature.