The branch of the Art of Drainage which relates to the removal of the focal and other refuse wastes of the population of towns, is quite different from that which has been described in the preceding pages, as applicable to the agricultural and sanitary improvement of lands under cultiva tion, and of suburban districts. Still, the fact that town and house drainage affords a means for the preservation of valuable manures, justifies its discussion in an agricultural work, and "draining for health" would stop far short of completeness were no attention paid to the removal of the cause of diseases, which are far more fatal than those that originate in an undrained condition of the soil.

The extent to which these diseases, (of which typhoid fever is a type,) are prevented by sanitary drainage, is strikingly shown in the extract which commences this chapter. Since the experience to which this report refers, it has been found that the most fatal epidemics of the lower portions of London originated in the choked condi tion of the street sewers, whose general character, as well as the plan of improvement adopted are described in the following "Extracts from the Report of the Metropolitan Board of Works," made in 1866.

"The main sewers discharged their whole contents di'rect into the Thames, the majority of them capable of 66 being emptied only at the time of low water; conse"quently, as the tide rose, the outlets of the sewers were "closed, and the sewage was dammed back, and became 'stagnant; the sewage and impure waters were also 'constantly flowing from the higher grounds, in some in'stances during 18 out of the 24 hours, and thus the thick 'and heavy substances were deposited, which had to be 'afterwards removed by the costly process of hand labor. "During long continued or copious falls of rain, more par "ticularly when these occurred at the time of high water "in the river, the closed outlets not having sufficient stor"age capacity to receive the increased volume of sewage,

"the houses and premises in the low lying districts, espec "ially on the south side of the river, became flooded by "the sewage rising through the house drains, and so con"tinued until the tide had receded sufficiently to afford a 66 vent for the pent-up waters, when the sewage floweu "and deposited itself along the banks of the river, evolv "ing gases of a foul and offensive character.

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"This state of things had a most injurious effect upon "the condition of the Thames; for not only was the sew"age carried up the river by the rising tide, at a time "when the volume of pure water was at its minimum, and quite insufficient to dilute and disinfect it, but it was "brought back again into the heart of the metropolis, there to mix with each day's fresh supply, until the gradual progress towards the sea of many day's accumulation "could be plainly discerned; the result being that the por❝tion of the river within the metropolitan district became 66 scarcely less impure and offensive than the foulest of the sewers themselves.

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"The Board, by the system they have adopted, have "sought to abolish the evils which hitherto existed, by "constructing new lines of sewers, laid in a direction at "right angles to that of the existing sewers, and a little "below their levels, so as to intercept their contents and 66 convey them to an outfall, on the north side of the Thames "about 114 miles, and on the south side about 14 miles, "below London Bridge. By this arrangement as large a "proportion of the sewage as practicable is carried away "by gravitation, and a constant discharge for the remain"der is provided by means of pumping. At the outlets, "the sewage is delivered into reservoirs situate on the "banks of the Thames, and placed at such levels as enable "them to discharge into the river at or about the time of "high water. The sewage thus becomes not only at 66 once diluted by the large volume of water in the river at "the time of high water, but is also carried by the ebb

26 miles below London Bridge, and its return by the fol "lowing flood-tide within the metropolitan area, is effec "tually prevented."

The details of this stupendous enterprise are of sufficient interest to justify the introduction here of the "General Statistics of the Works" as reported by the Board.

"A few statistics relative to the works may not prove "uninteresting. The first portion of the works was com"menced in January 1859, being about five months after "the passing of the Act authorising their execution. "There are 82 miles of main intercepting sewers in London. "In the construction of the works 318,000,000 of bricks, "and 880,000 cubic yards of concrete have been used, "and 3,500,000 cubic yards of earth excavated. The cost, "when completed, will have been about £4,200,000. The "total pumping power employed is 2,300 nominal "horse power: and if the engines were at full work, night "and day, 44,000 tons of coals per annum would be used; "but the average consumption is estimated at, 20,000 tons. "The sewage to be intercepted by the works on the north "side of the river, at present amounts to 10,000,000 cubic "feet, and on the south side 4,000,000 cubic feet per day; "but provision is made for an anticipated increase in these "quantities, in addition to the rainfall, amounting to a to"tal of 63,000,000 cubic feet per day, which is equal to a "lake of 482 acres, three feet deep, or 15 times as large as "the Serpentine in Hyde Park."

A very large portion of the sewage has to be lifted thirty-six feet to the outfall sewer. The works on the north side of the Thames were formally opened, by the Prince of Wales, in April 1865.

In the hope that the immense amount of sewage, for which an escape has been thus provided, might be profitably employed in agriculture, advertisements were inserted in the public journals asking for proposals for carrying out such a scheme; and arrangements were subsequently made

for an extension of the works, by private enterprise, by the construction of a culvert nine and a half feet in diameter, and forty miles in length, capable of carrying 12,000,000 cubic feet of sewage per day to the barren sands on the coast of Essex; the intention being to dispose of the liquid to farmers along the line, and to use the surplus for the fertilization of 7000 acres, (to be subsequently increased,) which are to be reclaimed from the sea by embankments and valve sluice-gates.

This project has not been carried into effect.-(3d ed.) The work which has been done, and which is now in contemplation, in England, is suggestive of what might, with advantage, be adopted in the larger cities in America. Especially in New York an improved means of outlet is desirable, and it is doubtful whether the high rate of mortality of that city will be materially reduced before effective measures are devised for removing the vast accumulations of filth, which ebb and flow in many of the larger sewers, with each change of the tide; and which are deposited between the piers along the river-sides.

It would be practicable to construct a main receiving sewer under the river streets, skirting the city, from the vicinity of Bellevue Hospital on the east side, passing near the outer edge of the Battery, and continuing to the high land near 60th street on the west side; having its water level at least twenty feet below the level of the street, and receiving all of the sewage which now flows into the river. At the Battery, this receiving sewer might be connected, by a tunnel, with the Brooklyn shore, its contents being carried to a convenient point south of Fort Hamilton,where their discharge, (by lifting steam pumps), into the waters of the Lower Bay, would be comparatively unobjectionable. The improvement being carried out to this point, it would be interesting to consider the advantages to result from the application of the sewage to the sandy soil on the south side of Long Island.

The effect of such an improvement on the health of the city, which is now in constant danger from the putrefying filth of the sewers, (these being little better than covered cess-pools under the streets,)—would, no doubt, equal the improvement that has resulted from similar work in London.

The foregoing relates only to the main outlets for town sewage. The arterial drainage, (the lateral drains of the system,) which receives the waste of the houses and the wash of the streets, is entirely dependent on the outlet sewers, and can be effective only when these are so constructed as to afford a free outfall for the matters that it delivers to them. In many towns, owing to high situation, or to a rapid inclination of surface, the outfall is naturally so good as to require but little attention. In all cases, the manner of constructing the collecting drains is a matter of great importance, and in this work a radical change has been introduced within a few years past.

Formerly, immense conduits of porous brick work, in all cases large enough to be entered to be cleansed, by hand labor, of their accumulated deposits, were considered necessary for the accommodation of the smallest discharge. The consequence of this was, that, especially in sewers carrying but little water, the solid matters contained in the sewage were deposited by the sluggish flow, frequently causing the entire obstruction of the passages. Such drains always required frequent and expensive cleansing by hand, and the decomposition of the filth which they contained produced a most injurious effect on the health of persons living near their connections with the street. The foul liquids with which they were filled, passing through their porous walls, impregnated the earth near them, and sometimes reached to the cellars of adjacent houses, which were in consequence rendered extremely unhealthy. Many such sewers are now in existence, and some such are still being constructed. Not only are they unsatisfactory, they are