Chap. VIIT.

BRITAIN.

5*IS

on the land side from 2 to 1. Culverts, 4 feet in diameter, founded on piles and crosstimbers, with sluices and flood-gates on each side the wall, served to let out the water whenthe wall was completed, the gates being put at the lowest level of spring tides. The wingwalls of these culverts, built of rubble masonry, were founded on a bed of concrete; theseflood gates can be used either to admit the tidal waters for the purposes of irrigation, orfor the passage of the land water; to carry away the silt that may accumulate in the channelcatchwater drains arc puddled, which collect the land waters on all sides, and convey themto the sluices with a proper fall.

The embankment contains within it a bed of puddle, 4 feet G inches in width at bottom,and 3 feet at top, and on the water side is placed a strong facing of fascines G feet thick atbottom, and 4 feet at top, embedded in the soil, and laid in an oblique direction, with a diptowards the land side; they are all held down by irons, which pass at right angles throughtheir entire height. On the land side they are covered with sods of turf; the cost of thiskind of embankment, including the sluices and puddle in the centre, is about 12 pounds peryard run.

Drainage of Ton'ns -Much has lately been written on the value of manures, and attention

has been directed to the great waste which is permitted, by the sewers of the metropolisdischarging their contents into the Thames , to he carried away by the current and thetide, injuring the quality of the water, and rendering the district through which it passesunhealthy ; numerous plans have been suggested, by which much that is valuable to theagriculturist could be saved and made serviceable to the growth and improvement of vege-tation. In Paris , where there are no sewers, every means is taken to prevent waste of thatwhich is important to the wine-grower, and a considerable trade is carried on in the capitalby collecting all that will serve for manure, and arrangements made to convey it to the mostsouthern provinces. A vast portion of London might have its sewage directed into largereservoirs in the marshes, at a distance on each side of tlie Thames, where the contentsmight he separated and dispersed throughout the neighbouring district, or be conveyed bywater to any part of the empire in need of it. The expense of such a scheme would he sosmall, compared with the immense advantages, that it is surprising public attention has notbeen directed to it; it has been computed that 1,000,000 tons of manure might easily beobtained annually, the value of which would he very considerable.

To carry out such a system, the property of individuals would perhaps be interfered with,and objections would be made to changing the character of the sewers; the most economicalmethod is that of having movable casks placed in the vaults under the pavement, intowhich all the pipes of the dwelling might drain; and if these casks were arranged so thatone was devoted to retain the solid matters and the other the liquid, or pipes laid tocarry ofF the latter into the sewer, the valuable portions useful for manure could be easilycarted away as often as it was found convenient. Such is tlie method practised by thecompany in Paris , and no inconvenience or annoyance is found to arise from it; the casksare the property of the company, who keep them in an excellent state of repair.

Before the fire of London , little or no attention was paid to carrying ofT the surpluswaters from the city ; it was suffered either to run upon the surface, or through the channelswhich the small streams had formed. After that calamity, it was enacted “ that thenumber and places for all common sewers, drains, and vaults, should be directed by someone or more appointed under the common seal,” and from this period we may date theauthority of the commissioners of sewers in the metropolis ; for some of the larger towns inthe kingdom, similar enactments were obtained soon after.

Although the sewers in the city exceed in length 15 miles, it is still not thoroughlydrained ; one of the best constructed is that which carries off the waters from Moorfields,which is 7 feet in width, and 8 feet 6 inches in height. The other sewers vary in theirdimensions; some are 4 feet 3 inches high, and 2 feet 3 inches in width, and others 5 feet by3 feet, but none are made less than will enable men to enter and thoroughly cleanse them.The whole drainage of the city is into the Thames .

Westminster and a portion of Middlesex is under another commission, who have tliecontrol over 134 miles of arched or covered sewers, of which 93 are constructed with curved,the rest with flat bottoms.

Ilolborn and Finsbury districts comprise the northern parts of the metropolis.

The Tower Ilamlets commission extends over 45 miles of sewer, and since the year1830, upwards of 11 miles of new sewers have been built under its direction.

Surrey and Kent commission takes in the southern .side of the metropolis; since tlie year1820, nearly 21 miles of sewer have been constructed ; previously the greater portion wasonly a surface drainage.

The Regent Street has a commission which manages its drainage, and there is so generala desire throughout the metropolis to have all the sewers covered or inclosed, that the openones are fast disappearing, although the commissioners have no power whatever to makenew covered sewers, by which tlie effluvia arising from them, so prejudicial to health, shallbe confined.