IX. The main sewer-pipe must have a fall of at least one-half inch to the foot. When practicable it must be run on the cellar-wall, securely fastened thereto, and must in such case be of iron. When it is impracticable to run the sewer-pipe on the cellar-wall, it may be laid in a trench beneath the basement or cellar floor, and may in such case be either of iron or earthenware, as hereafter specified. This trench must remain open until this Department gives permission to close it.

X. That where sewer-pipes are to be placed in the ground, cast-iron pipes one-half inch in thickness, or glazed earthenware pipes one and a quarter inches in thickness, and with hubs three inches deep, will be required; that joints on earthen pipes must be made with Portland cement, sand, and iron filings, thoroughly mixed before wetting with a weak sal-ammoniac solution; that all pipes laid beneath the ground, whether iron or earthen, must be filled with water, and shown so filled to the inspector.

XI. The main sewer must be trapped with a running trap of the same material and size as the sewer-pipe, and must be located inside the front wall of the building. No connection with the house-sewer for the discharge of sewage or rain-water shall be made on the street side of said trap. The trap must be provided with a hand-hole, for convenience in cleaning. There must be a fresh-air inlet-pipe entering the sewer-pipe inside and close to the said trap, of a diameter not less than three inches, leading to the outer air, and opening at any convenient place away from windows.

XII. Hand-hole openings, four inches in diameter, must be provided on all pipes laid beneath the ground; said openings to be closed with brass ferrule and screw-cap, and one such opening be required at each branch, and one at each end of the cellar in the main line; said screw-caps to project above the level of the cellar-floor; or, if they do not project above the cellar-floor, manholes must be provided in order to give access to them.

XIII. An opening must be provided in the cellar-walls of all buildings for the entrance of the sewer-pipe; said opening to be two inches clear of the pipe on the top and both sides, to avoid injury by settlement.