200THE ' ANCHOLME' DRAINAGE.but it would also confer considerable benefit upon the districts in the Ancholme, and the Witham, by opening a ready and economical communication between Hull, Brigg, Lincoln, Boston, and Barton, far superior to what they at present enjoy, and would not only confer the greatest advantages upon all those places, but would produce a profitable return for the capital expended in carrying it into effect. The paper is illustrated by ten drawings (Nos. 3713 to 3722), comprising a general plan of the level of hncholme, with elevations and sections of the various stone, iron and timber bridges in the district and also of the Ferraby sluice.--Mr. J. OLDHAM bore testimony to the success of the works of the Ancholme drainage, in the beneficial effects they had produced in the district, and mentioned particularly, the construction of the new sluice at Ferraby, a minute description of which, he suggested, would form an interesting communication for the Institution.Sir JOHN RENNIE, President, said, it would be observed, that in the paper, he had brought prominently forward, some leading principles of drainage, which he thought were very important.These were, Ist, The formation of ' catch-water' drains, which separated the highland from the lowland waters, and conveyed each to independent sluices, at the lowest practicable outfalls. This system was, he believed, first practised by the late Mr. Rennie, about the year 1801, in the Witham drainage.2nd, The straightening, deepening, and general improvement of the main river, separating, as much as possible, the navigation from the drainage ; and3rd, The formation of over-fall weirs and reservoirs, for arresting the sand and mud, and preventing the drains from being choked.The advautages of these plans must be evident, particularly for a flat district, surrounded by high lands. He was of opinion, that the defects, complained of in the Bedford level, might be attributed, in a great degree, to the neglect of these principles, and the continuance of the old Dutch plan, of simply cutting a series of straight drains to the nearest point in the river, without sufficient regard to the outfall, where only as much of the water was discharged, as was allowed by the time the sluice gates could be permitted, on account of the tide, to remain open. This plan alone was, he believed, still pursued in Holland. The attempts to drain the Pontine Marshes, under Pius VII., had been conducted on that principle, and even M. Prony, who was sent to Italy by Napolbon, for the purpose of reporting on the drainage of those marshes, made no other suggestion.
