Sewer

In military architecture, a drain, conduit, or conveyance, for carrying off water, foliage, . It is nece ary that every building have conveniencies for discharging its refuse water, and other usele and offensive matters. These are obtained by digging and laying sewers and drains at proper depths, and with the nece ary outlets: the great care is, that they be large enough; that they be placed sufficiently deep, and have a proper descent; that they be well arched over, and have so free a pa age, that there be no danger of their choaking up; the cleaning them being a work of trouble and expence. Instead of making the bottom of the sewer a flat floor, it should be in the form of an inverted arch, answering in part to the sweep of the arch above. Every one knows that the freest pa age is through circular channels; and these might easily be constructed so as to wear that form; they would resemble so many water-pipes of a circular base, and there would be no danger of their filling up. The perpendicular walls would not retain any thing, because there are no angles in their joining; and the bottom being round and free, all would run off. These circular sewers are with us called culverts .