Engineering Wonders of the World
Volume III

HOW LONDON GETS ITS WATER. 203 west. These arches and the piers carry the roof, which consists of a series of parallel brick- work segmental arches running * north and south, covered with a 6-inch layer of cement concrete, above which is the clay and top soil originally taken from the site. Two walls at right angles to each other divide the reservoir into four sections. At the point where the walls cross is a valve house for the valves controlling the supply, north or Essex side, the smaller portion in Middlesex. Entering at the main gateway, we are confronted by a large engine-house, in which two great Cornish engines, the “ Prince ” and “ Princess,” have been busily at work since ing water to a reservoir at Finsbury Park. Overhead rocks up and down the mighty beam of each engine, its ends pulled down Cornish Pumping Engines. 1867 deliver- RIVER LEE DIVERSION—ON RIGHT—WHICH CARRIES THE RIVER ALONG THE EAST SIDE OF THE CHINGFORD NEW RESERVOIR. On the left is a tributary of the Lee. draw-off, and intercommunication of the sec- tions, each of which can be filled or emptied independently of the others. As the pumping stations, filter beds, etc., resemble one another closely in their general arrangement, and as the principles of filter- ing are the same in all gravi- Lee Bridge Nation filter beds, it will suffice Pumping , , • i • x il Station ‘"° describe a single installa- tion. For our example we may select the Lee Bridge pumping station, which is one of the chief feeders of the East- ern district. The station is divided into two parts by the river Lee, the main portion being on the alternately by the pressure of steam on the upper side of the piston in the single cylinder of 7-foot bore and 11-foot stroke, and by the 22-ton weight attached to the top of the 45-inch plunger. The steam serves merely to raise the plunger ; the weight referred to does the forcing of the water—100 cubic feet, or about 600 gallons, per stroke—against a head of 140 feet. A Cornish engine has the disadvantage of occupying a great deal of room proportion- ately to its power, but is remarkably simple in its mechanism, and seldom needs any re- pair. Each engine is capable of delivering 10,000,000 gallons a day. Passing out of the engine-house, we are soon