Engineering Wonders of the World
Volume III

214 ENGINEERING WONDERS OF THE WORLD. Thames (50 square miles) alone would require a channel 500 feet wide and 10 feet deep, and a flow velocity of 200 feet (about 2| miles an hour) per minute. This showed the impossi- bility of carrying off a maximum fall of con- siderably over one inch an hour through sewers designed to act as efficient channels for ordinary sewage. of decades earlier. It was maintained that the river had been rendered dangerous to navigation and to health by noxious deposits. Inquiries PolIution of held in 1869 and at later dates Lower Thames. snowed that, as regards the formation of mudbanks, the sewage was not responsible ; but that about the seriously pol- PLAN OF BARKING OUTFALL WORKS. The large figures in circles denote the successive operations of liming, adding iron water, precipitation, sludge concentration, and delivery to the sludge vessels. The completion of Sir Joseph Bazalgette’s scheme closes what may be termed the second stage in the development of London drainage. Three huge culverts on the north, and one on the south, led all the crude sewage into the Thames at points about 14 miles below Lon- don Bridge—namely, Barking and Crossness. Unfortunately for the Metropolitan Board of Works, the inhabitants of Barking presently began to complain that the enormous volume of pollution transferred to this locality. repro- duced there the very unpleasant state of things against which Londoners had rebelled a couple luted condition of the river there could be no doubt. In 1884 the Commissioners appointed to investigate the matter reported that Lon- don sewage ought not to be discharged in its crude state into any part of the Thames ; that the solid matter should be separated from the liquid by some process of deposition or pre- cipitation, and be applied to the raising of low-lying lands, or be burnt or dug into the land, or carried away to sea ; that the liquid portion of the sewage might be allowed to pass into the river after being chemically clarified. As a result of this report the Board deter-