228

MODERN STEAM PRACTICE.

distinct beam, as at the other stations. Each engine works twopumps, having a diameter of 3 feet 10inches, and a length ofstroke of 4^ feet. The boilers are each 8 feet in diameter and30 feet long, with double furnaces.

The engine building is divided in height into three compartments,the lower one being the pump well into which the sewage is con-veyed from the Low Level Sewer, the second forming a reservoirfor condensing water, and the upper one containing the eight enginesand platform overhead. The lower part of this building lies about3 feet above the bottom of a thick stratum of clay, overlying a consid-erable thickness of sand with water, through which the foundationsare carried by piling to a bed of firm gravel below. The boiler housesand other portions of the work are founded upon the clay stratumoverlying the sand. As the deep foundations are situated in closeproximity to the Northern Outfall Sewer, which is contained in anembankment above the general level of the ground, great caution wasrequisite to prevent any settlement in that sewer. The boiler houseand coal Stores are built between the outfall sewer and the enginehouse, so as to keep the deep excavations as far distant from thesewer as practicable. The coal Stores are built with their floors levelwith the stoke holes in the boiler house, and tramways are laid fromone to the other; this floor is only a trifle below the surface of theground, which is 6 feet below high water. One side of the coalStores forms the front side of the boiler house. Tramways are laidfrom the top of the coal Stores to the Abbey Mill River, adjacentto the works, where a wharf wall is built for landing coal and othermaterials.

The sewage from the Low Level Sewer, before entering the pumpwells, passes through open iron cages, the bars of which interceptany substances likely to interfere with the proper action of thepump valves; and these cages when requisite are lifted above groundby proper gearing, and the intercepted matter is discharged intotrucks. The sewage then passes into the wells, and is lifted by thepumps through the hanging valves into a circular culvert of castiron, and then forced into any of the three culverts forming theNorthern Outfall Sewers.

It is fortunate that these works were not projected in the year1306, when coal was first introduced into London , and was regardedas so great a nuisance that the resident nobility obtained a royalproclamation prohibiting its use under severe penalties; for this