Fig. 1.
The following figures, 1, 2, are representations of the sewers in the Holborn and Finsbury division of the metropolis, on the same scale as the above. The part in which the joints are marked in the cut is, according to the directions, to be worked in blocks with cement.
Fig. 1.
Fig. 2.
The sides of these sewers form the curves of large radii struck from the centres on the lines a a, the radius for the larger size being about 13 feet, and that for the smaller size in proportion.
The spaciousness of the sewerage in the Westminster division of the metropolis has been an object of pride; and it is stated that the commissioners have walked in procession down one main sewer prepared for the purpose. It was the glory of Rome that some of its cloacæ were so large that boats and chariots might pass through them. All this, however, appears to have been mistaken in principle, and in ignorance of the mischiefs of the generation of gases and of the principles of hydraulics, and their application for the attainment of the objects in question. Mr. Smith, of Deanston, who has introduced the greatest improvements in land drainage, advances the general principle, that the size of sewers should be so adjusted as to have them always as full as possible, with a quick flow; and he contends that the drainage of a city might and should be so constructed as to give rise to as little occasion for men to go through the main drains as there is for men to go through the main pipes for conveying supplies of water. He would make the drains narrow. “Their transverse section should exhibit an oval or egg-shape, having the vertical diameter at least double the length of the horizontal. The bricks used should be made on purpose, with radiating sides.” “Care should be taken to make the building water-tight and air-tight, and to prevent the foul water and effluvia passing into the contiguous soil. Where land drainage is to be received, special openings can be made at intervals to receive it. All private drainage should pass into the sewers under ground by well-secured channels or pipes. Strong clay pipes, of an oval section, hard burned, and with a good arrangement for secure jointing, might be cheaply procured for the purpose.” It may be said that there is scarcely any drainage, even in the opulent districts, that at present meets these conditions. E. C.]
2.—Evidence of Mr. John Darke, Contractor for Cleansing, as to the Obstacles to Cleansing, and the Conversion of the Refuse of the Metropolis to Productive Use.
What are the practical difficulties you find in the way of the cheap cleansing of the streets and houses of the metropolis?—The great difficulty of the cleansing of the metropolis arises from the want of proper receptacles for the filth. There is no filth in the metropolis that now, as a general rule, will pay the expense of collection and removal by cart, except the ashes from the houses and the soap lees from the soap-boilers; and some of the night-soil from the east end of the town, where there happen to be in the immediate vicinity some market-gardens, where it can be used at once, without distant or expensive cartage. The charge for removing night-soil from the poorest tenements may be about 1l. per tenement. One house with another, the expense may be said to be in London about 10s. per year, as the cesspools may be emptied once in two years. One house with another they will not produce more than a load of refuse from the cesspools, which, not being composed, there is great absorption of the liquid refuse. I have given away thousands of loads of night-soil; as we have no means of disposing of it, we know not what to do with it.