SEWER. In architecture, a subter raneous conduit, or channel, to receive and carry off the superfluous water and filth of a city. The sewers of Rome have been the models of those of the modern cities of Europe. They are as old as the elder Tarquin. These cloacaliad, between the Quinnal, Capitoline, and Palatine hills, many branches, which joining in the Forum, now the Campo Vaceino, were received for conveyance into the Tiber by a larger one called the cloaca maxima. It mustbe admitted, however, that it is erroneous to designate the Ro man cloacte by the term sewers. They were rather drains, made to carry off the stagnant water of the pestilential marshes which occupied much of the low ground near the Tiber, and the spaces between the Aventine, Palatine, and Capitoline hills. The height and width of the cloaca maxima are equal, each measuring 13i feet.
Sewers. The whole length of sewers in the City of New York, at the close of the year 1S50, was 125 miles, and during the present year there have been added, including what is now under contract, about 11 miles, making 136 miles in all, to be completed within the present year. The number now in progress is 54, at an average length of 800 feet; the average contract price of which is $5 12i per cubic foot. In addition to this, the con tractors are uniformly allowed $2 per cu bic yard for excavating rocks. Before this uniform price was established, it fre quently happened that bidders at a high nominal price obtained a contract in pre ference to a lower bidder, on account of a different estimate of the cost of blasting, or otherwise excavating the rocks, in which there is a great difference, not al ways ascertainable before the work is done. On the present plan the contrac tors, with a knowledge of the rates to be allowed, are supposed capable of judging of the proper rate for building the sewer, and their bids are always made with re ference to the fact.
In consequence of sewers not formerly being properly built, many of the old ones have required repairs which, under the present system of management, will rare ly be necessary. No person is now ap pointed to the office of inspector who 19 note practical mason, and in the absence of personal knowledge a certificate is re quired that the applicant has served a regular apprenticeship to that business. The care of the department, in the rigid enforcement of its rules, the exaction of sufficient bonds, and evidence of the act ual fulfilment of contracts, has produced better work, and is more fully performing its appropriate agency for the city than at any time heretofore.
Among other improvements, the form of the sewer has been changed from a round to an oblong, or rather an egg form, having the smallest diameter at the bot tom. This does not alter the capacity of the sewer, hut causes greater velocity of current, and helps the sewer to cleanse it self. This it would effectually do if the department shonld carry out the plan to which they have given seine considera tion, of flushing the sewers by means of the waste pipes of the Croton, in which case they would accumulate but little filth. The sluices are now so construct ed that while they readily receive the wa ter as well as the mud from the surfaces and gutters at every rain, the contamina ted air is effectually prevented from ris ing. The accumulation of dirt in these sluices is, in some localities, very great, two hundred loads having been, in one instance, taken from a single block in Canal-street.
The depth of the sewers is various, ac cording to the grade of the street or dis trict requiring to be drained. At their termination in the rivers, they are, as a general rule, between two and three feet below high water mark. From this point they rise with the average grade they are intended to drain, till they reach a nearly unifbnn rate of 131 feet below the curb stones. In some instances, how ever, the depth is 17 feet or more, where the grade of the street is more than of or dinary height--the object being to obtain in each instance the requisite average of elevation. For the necessary fall of wa ter three inches in 10 feet is regarded sufficient—but a greater rate is usually allowed.
In connection with the use of Croton water, the sewers are invaluable, and the full benefit of the Croton could not be ob tained without them. To perceive this, it is scarcely necessary to refer to the fa cilities afforded in bathing-houses, water closets, manuthetories, hotels, and other places, where large quantities of water, more or less impure, must flow off through the sewers, or render the atmosphere un wholesome by being discharged upon the surface of the ground.
So important a matter is it now regard: ed by builders and owners of lots, that scarce a building is now commenced with out an inquiry first at the CrotonWater De partment whether the street•ias a sewer, and at what depth a cellar may be expect ed to be drained. This is the more im portant, since by the disuse of wells, the level of water in the city has generally risen to a higher line than formerly.
The cost of the 54 sewers now tinder contract, to he completed within the pre sent year, is about 135,000 dollars.