The subject of the application of sewage refuse to the purposes of manure has recently attracted much attention. Two companies obtained acts of parliament, the one in 1840, and the other in 1847, under the designations of the 'Metropolitan Sewage Manure Com pany,' and the London Sewage Chemical Manure, Company.' The plan of the former company was to collect the contents of some of the sewers of Westminster and Pimlico, and convey them by a deep underground ' channel to Hammersmith, where a steam engine and- other apparatus would distribute the manure in a liquid state to the market gardens of that neighbourhood. The plan of the second company was to collect the contents of three sewers which now fall into the Thames between Vauxhall Bridge and West minster Bridge, and, after allowing the liquid part to flow into the Thames, to deprive the refuse of its offensive smell, and sell it as manure in a solid state, Very little has been done, however, towards carrying out either of these plans.
Since the Metropolitan Commissioners of Sewers commenced their operations in 1847 many steps have been taken towards a com prehensive sewerage for the whole of the metropolis. A survey of the metropolis is now being made for the Commissioners by the officers belonging to the Ordnance Survey. The survey will extend to a distance of 8 miles in every direction from St. Paul's, com prising an area of about 201 square miles. On a scale of five feet to a mile, the results of this survey would fill 900 large sheets, and would form a magnificent map of London eighty feet in diameter. While the survey and map are in progress, the Commissioners have invited tenders of plans for a comprehensive sewerage of the metropolis. A very large number of such plans were sent in. to the commissioners in the early part of the year 1850; many of these embracing an application of sewage refuse to the purposes of manure.
The Metropolitan Commissioners have not yet begun to develope their great system for the drainage of London ; but they executed in 1850 many important works which will be made compatible with their larger scheme. They expended 70,000/. during the year in forming 6 miles of brick sewers, 16 miles of pipe sewers, 46 side entrances, 304 air shafts, 565 gullies, 1137 drain mouths, and various repairs. Besides the 21 miles of new sewers
executed at the expense of the Commissioners, there were 13 miles constructed for, and paid for by, private parties. About 18,000/. had been expended by the end of the year in the survey of London. Of the 000 sheets about 400 are to be engraved, and the rest (the marginal or country district) left simply as drawn plans. Nearly all the 400 are now (April 1851) engraved ; they are printed on sheets of double elephant paper, and are sold singly at two shillings each.
The Commissioners determinld on the adoption of two comprehensive schemes of drainage for the Metropolis ; they directed their engineers to prepare plans, and reports were made in August 1850 and January 1851, respecting the south and north drainages respectively. The general principle of these schemes is understood to be accepted by the Commissioners: the southern to be com menced before the northern, as being more urgently wanted. Without entering into details, it may suffice to say, that the object both of the north and the south drainage is to keep the Thames clear of sewage from Galleon's Reach upwards ; to carry the sewers as much as possible under the public streets and places ; to make them of dimensions and at gradiants ensuring an unintermittent flow ; to secure good house-drainage, and self cleansing street drainage ; to dispense, as far as possible, with periodical flushing ; and to means for the eventual removal of all open sewers, ditches, and cesspools. A portion of the great scheme for the southern side of the Thames has been already commenced between Kennington and the Old Kent Road. To give some idea of the magnitude of the operations which the Commissioners have under their control, it will suffice to say that 700 miles of existing sewer have been examined north of the Thames, and accurate plans and sections taken of every part of every sewer. It will farther illustrate the scale of these operations to bear in mind that the esti mate of expense for the northern drainage alone is nearly a million and a quarter sterling.