A perfect method of disposal of excreta and other house refuse would be one which would insure their prompt and rapid removal in such a way as to prevent the contamination of the air of any inhabited locality during such removal, or after their final deposition. The most convenient and economical means yet invented of accomplishing this object is =water-carriage=; i. e., the matters referred to are conveyed from the house, with the addition of sufficient water to insure a rapid flow, through a series of pipes and tunnels into a large body of running water, or over the surface of the earth, under conditions which insure their rapid conversion into harmless substances. The water-carriage system includes bowls or sinks for the deposit of refuse matters, connecting-pipes to remove such matters from the house, and public sewers for their further conveyance away from human abodes. The construction and care of public sewers belong to the local government; we have here only to do with house-drainage. The essentials of house-drainage are: 1. The primary receptacles (bowls, sinks, water-closets, etc.) should be of such material and so constructed as to be impervious to fluids, and easy to clean and keep clean. 2. The pipes should be of such material as to be as durable as possible, and so laid and connected as to form gas-tight conduits, and to insure the rapid passage of whatever enters them, so as to prevent the formation of deposits or incrustations. 3. The drainage system should be so planned and constructed that neither the atmosphere of the house nor the drinking-water can be polluted by anything escaping from it, and no noxious matters can enter it from any other house. The following plan of construction is that recommended by the Board of Health of New York city: 1. All materials must be of good quality and free from defects; the work must be executed in a thorough and workmanlike manner. 2. The arrangement of soil and waste pipes must be as direct as possible. 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.