STATIONARY ENGINES.

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pumping Station alone consumes about 9700 tons of coal per annum.The expense of pumping, however, cannot be regarded as a whollyadditional item in the cost of drainage under the new System; forthe removal of deposit from the tide-locked and stagnant sewers inLondon formerly cost about .£30,000 per annum, and the constantflow kept up in the sewers by means of pumping must necessarilykeep them freer of deposit, and so reduce the outlay for cleaningthem.

The Deptford Pumping Station is situated by the side of Dept-ford Creek, and close to the Greenwich Railway Station. Thesewage is here lifted from the Low Level Sewer, a height of 18 feet,into the Outfall Sewer. An iron wharf wall and bärge bed, 500 feetlong, has been constructed at the side of the creek, and is providedwith a crane and tramways for landing coal or other materials.There are four expansive, condensing, rotative beam engines, each125 horse-power, and capable together of lifting 10,000 cubic feetof sewage a height of 18 feet per minute. These engines are sup-plied by ten Cornish single-flued boilers, each 30 feet long and6 feet in diameter. The cylinders are 48 inches in diameter, witha length of stroke of 9 feet. The pumps, two of which are workedby an engine direct from the beam, are single-acting plunger pumps,the diameter of the plungers being 7 feet, and the length of stroke4 Yi feet: one pump is worked from the beam midway between thesteam cylinder and the centre pillars, and the other midway betweenthe centre pillars and the fly wheel. The air, feed, and cold-waterpumps are worked by a separate beam attached to the cylinder endof the main beam. The pump valves are of the leather-faced hangingkind, and the sewage is discharged through them into a wrought-iron culvert placed on the level of the Outfall Sewer, with which itis connected by a brick culvert, which receives also the sewage fromthe High Level Sewer, previously brought by gravitation under thecreek through four cast-iron pipes 3 feet 6 inches in diameter.Both streams enter the Outfall Sewer, and are conveyed to Cross-ness, where they are again lifted. The chimney shaft at this Stationis 7/4 feet in diameter at the base and 6 feet at the top; its heightis 150 feet, and the furnaces draw from the sewers and the engine-well to assist in their Ventilation. The accommodation for coal isample, the sheds covering an area of 18,000 feet. Grätings areused for intercepting the larger substances brought down by thesewers, in the same manner as at the other pumping stations.