3. The drain, soil, and waste pipes, and the traps, must, if practicable, be exposed to view for ready inspection at all times, and for convenience in repairing. When necessarily placed within partitions or in recesses of walls, soil and waste pipes must be covered with wood-work, so fastened with screws as to be readily removed. In no case shall they be absolutely inaccessible.

4. It is recommended to place the soil and other vertical pipes in a special shaft, between or adjacent to the water-closet and the bath-room, and serving as a ventilating shaft for them. This shaft should be at least two and a half feet square. It should extend from the cellar through the roof, and should be covered by a louvered sky-light. It should be accessible at every story, and should have a very open but strong grating at each floor to stand upon.

Shafts not less than three feet square in area are required in tenement-houses, to ventilate interior water-closets.

5. Every house or building must be separately and independently connected with the street-sewer.

6. Where the ground is made or filled in, the house-sewer—that is to say, the portion of the drain extending from the public sewer to the front wall—must be of cast-iron, with the joints properly calked with lead.

7. Where the soil consists of a natural bed of loam, sand, or rock, the house-sewer may be of hard, salt-glazed, and cylindrical earthenware pipe, laid on a smooth bottom, free from all projections of rock, and with the soil well rammed to prevent any settling of the pipe. Each section must be wetted before applying the cement, and the space between each hub and the small end of the next section must be completely and uniformly filled with the best hydraulic cement. Care must be taken to prevent any cement being forced into the drain to become an obstruction. No tempered-up cement shall be used. A straight-edge must be used inside the pipe, and the different sections must be laid in perfect line on the bottom and sides.

8. Where there is no sewer in the street, and it is necessary to construct a private sewer to connect with a sewer on an adjacent street or avenue, it must be laid under the roadway of the street on which the houses front, and not through the yards or under the houses.

9. The house-drain must be of iron, with a fall of at least one quarter inch to the foot, if possible, and not more than one inch to the foot.

10. Where water-closets or a school-sink discharge into it, the drain must be at least four inches in diameter.

11. It must be hung on the cellar wall or ceiling, unless this is impracticable, in which case it must be laid in a trench cut at a uniform grade, walled upon the sides with brick laid in hydraulic cement, and provided with movable covers, and with a hydraulic concrete base of four inches in thickness, on which the pipe is to rest.