SEWER. A subterranean channel or canal, formed in cities, towns, and other places, to carry off water and other matters. The construction of the common sewers in general use in the metropolis, is represented in the subjoined ses,tion. A is the paved roadway of a part of a street ; B the paved footpath; C the grating above ground, covering the entranca to sewer ; D D the solid earth ; E the entrance from the street, called the well, and opening into the branch or collateral sewer I, which leads into sewer J, represented in perspective ; the light in the distant portion designating the opening of another collateral sewer into it.
As the health of the inhabitants of a great city mainly depends upon frequent cleansing, and the getting rid, in particular, of foul waters and all substances capable of the putrefactive fermentation, it will not be out of place if we notice the leading defects of the present plan. In fact, the London sewers are the abodes of pestilence, owing to the large quantities of animal and vegetable matter that are constantly being swept into them, where they undergo decom position, and send forth their noxious exhalations through the gratings. In the neighbourhood of distilleries, brew-houses, dye-houses, &c., large quantities of hot liquid are frequently poured off into the sewers, which accelerates the fer mentative process ; and when the water is in considerable quantity, as in the cue of a smart shower of 'rain, the putrefactive matter is stirred up, and the surrounding inhabitants are doomed to breathe the contaminated atmosphere. Large quantities of rubbish and filth are also frequently forced through the gratings, and much of the matter is too ponderous to be carried off by the cur rent, but falling from the grating upon the inclined plane of the collateral sewer, they are projected forward, and are collected in a mass at 0, where it continues to increase; and the same effect takes place at the end of each col lateral sewer, till, at the end of a few years, the accumulation chokes up the sewer entirely, so that nothing more can pass through it. Then, from neces sity, commences a very annoying and tedious operation; the street is stopped up, the pavement removed, and the sewer laid open to clear out the vast accu mulation of filth. This done, the arching is rebuilt, the ground remade, and the paving repeatedly laid afresh, before an even settlement takes place. The cause of this choking up, however, remaining unaltered, the same occurrence takes place a few years afterwards, and recourse in again had to re-opening, re cleansing, and rebuilding, only to be renewed after a similar interval of time.
To pay the enormous expenses thus incurred, a heavy tax called a sewer-rate is levied upon the inhabitants, and placed in the hands of the Commissioners of Sewers, who, seemingly, find it to their individual advantage to disburse the Rinds in their old way, without regard to various improved plans, which base been repeatedly submitted to their consideration and adoption. A very simple plan for their improvement was proposed by Mr. Joseph Cuff', which that gen tleman strenuously endeavoured to get a fair trial made of, but, we believe, with little success in the metropolis, though it has been adopted, we undersignd, in Liverpool and some other provincial towns. The figure on the followirg page is descriptive of the alteration proposed by Mr. Cuff; it represents a section of a street to the same scale as the preceding figure, in which the same letters of reference indicate corresponding parts ; A being the roadway of the street ; B footpath; C the grating ; D D solid earth; E the well ; F supernatant water ; G a cesspool, with the ponderous matter lying in it; H the curtain, or dipping valve ; I the branch or collateral sewer, leading into the main sewer. It will be readily perceived, that atones and all ponderous matter cannot enter this sewer: that nothing but water or matter in solution can pass into it, which quickly flows off when above the level of the collateral sewer, as shown in the engraving. The silt collected at the bottom of the well lies in a quiescent state, and the water, which covers it to the depth of several feet, effectually prevents all noxious exhalations ; acting precisely as the " stink-trap" commonly used in the sinks and drains of private houses ; and, like them, the supernatant water is constantly being changed by fresh accessions of the fluid running into the sewer. The cesspool is cleared out once a month, or oftener, if required, by means of proper rakes and tool; and is the work of only about twenty minutes, but it is proposed to have, in some instances, cast-iron receptacles to fit the bottom of the well, which are to be drawn up by a crane connected to the care which carries away the silt and ponderous rubbish. If at any time a !mil smell should be emitted, the remedy is easy, quick, and of trifling expense.