[208] The New York Board of Health require that earthenware drain pipes connecting dwellings with street sewers shall be hard and salt glazed, sound and cylindrical; at least ⁵⁄₈ths of an inch thick if 5 inches in diameter, and ³⁄₄ of an inch thick if 6 inches in diameter. Pipe must be connected with hydraulic cement of the best quality. No “tempered up” cement can be used. The pipes must be laid with such good alignment that the inspector can see through the entire line from the house to the sewer, and every section must be bedded in cement so as to have a firm bearing, not only at the hub, but along its entire length. The inside of the drain must be freed from all cement which may have oozed through at the joints, and from all other obstructions. Before the drain is covered notice must be sent to the Health Department, by the owner or plumber, that the inspector may visit and examine the work, and the Board of Health will not approve or permit a drain which has not been examined by one of its inspectors and found to be properly constructed. [209] See chapter on “Breaking up Streets.” [210] The definition of house is as follows:--“House” includes schools, also factories and other buildings in which more than twenty persons are employed at one time. (38 & 39 Vic. c. 55, s. 4) [211] Notices, orders, and other such documents under this Act may be in writing or print, or partly in writing and partly in print; and if the same require authentication by the local authority, the signature thereof by the clerk to the local authority or their surveyor or inspector of nuisances shall be sufficient authentication (38 & 39 Vic. c. 55, s. 266). [212] Having obtained admission to the premises, the inspection of the alleged nuisance should be so conducted as to enable the local authority to determine whether it exists, or whether it existed at the time the notice was given, and whether, although it has since been removed or discontinued, it is likely to recur or to be repeated; and in all cases it will be the most expedient course to reduce to writing the result of the inspection. When the inspection is made by an officer of the local authority, it will also be expedient for that authority, on receiving the report of their officer formally and in writing, to record the conclusions to which they have come after considering his report in order to ground further proceedings. (_Vide_ ‘Law of Public Health and Local Government,’ by W. C. and A. G. Glen, 8th edition, p. 81.)