Discussion. On the Drainage of Towns.

Abstract

Mr. RAWIJNSON admitted, that his paper might be considered loose and discursive, but he had written it chiefly for the purpose of eliciting opinions on a question of great social importance, and he was ready, in answering the questions put to him, to afford any additional information in his power. I t might be said, that there were some positions unduly assumed ; if so, they would be overthrown, and the erroneous conclusions would be pointed out.Perhaps the best method of opening the discussion was to state a few facts, in connexion with the drainage of a town, where, from local circumstances, only earthenware pipes had been used. He alluded to the town of Hitchen, where upwards of 60,000 feet of pipe sewers, from 20 inches down to 4 inches diameter, and 2 feet 6 inches long each, had been in action for four months, with perfect success ; the average depth below the surface was 8 feet, and the outlet of the main sewer, which was 5000 feet in length, and only 20 inches in diameter, was laid, in part, beneath the bed of the river, at an inclination of one in eight hundred.This was designed for the sewerage of one thousand houses, of which only two hundred were at present connected, and for eleven hundred acrea of urban and suburban drainage. H e admitted, that some of the pipes, laid to a pumping engine, had been broken, from being laid in bad ground, but after being relaid in wooden troughs, no further fractures ensued. He was aware, that the system of' pipe sewerage had been, and must be, modified in practice, to adapt it to certain localities ; that in a rocky uneven bed, improperly loaded pipes would break, and if of large dimensions, they were very liable to be split longitudinally, or be fractured transversely, as it was very di5cult to get them accurately made and burned, and the false bearing at the sockets caused breakage. If in the case of Hitchen, the rule laid down in Mr. Roe's tables had been followed, the outlet must hau-e been 5 feet diameter, instead of 20 inches diameter.No attempt had been made to divert the natural flow of the surface-water ; the street gullies being connected directly with the pipe sewers. In this, as in the arrangements for all towns, an engineer must modify his practice to meet local circum, Qtances. H e was satisfied with the general results a t Hitchen, and as the