These Pumping Engines, which have been constructed at the writer's works, are situated at Crossness Point, where the Southern Outfall Sewer for the drainage of the southern portion of London discharges into the Thames, about four miles below Woolwich. This outfall sewer being at a low level, with its bottom about 8 feet below the mean low-wat,er level, the sewage has to be lifted by pumping, to a level sufKciently high for discharging it into the river soon after high water; the time for

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... ge is restricted to that period, for the purpose of getting the sewage a t once carried out to sea by the ebb tide, and preventing any of it from floating upwards on the river. The sewage is therefore pumped into a large covered reservoir at a higher level, where it is accumulated by continuous pumping during the period of low water and 3ood tide j and from this reservoir it is allowed to flow out direct into the river, its soon as the time of high water has passed and the ebb tide is running. The reservoir is shown at A A in the general plan and section, Figs. 1 and 3, Plate 76, and to a larger scale in the section, Fig. 5 , Plate 77. It consists of four compartments, each roofed over by eight parallel brick arches of about 15 feet span, carried upon piers about 20 feet apart. The whole reservoir is 560 feet long and 520 feet wide ; the average height to the crown of the arches is 1 7 feet, and the reservoir contains 24 million gallons when filled to a depth of 15 feet, the level of the overflow weirs. The sewage is brought from the main outlet sewer B, which is 11i feet diameter, by the low-level culvert C, Figs. 1, 4, and 7 , discharging by two branches into the two pump wells D D, situated at opposite ends of the engine house. The sewage on entering