IV. _Diphtheria._--Elegant mansion, regarded by owner and "practical plumber" as a model of sanitary construction. Soil-pipe extended above roof, but without ventilation at its foot. Materials and workmanship good. On a lateral branch was a down-stairs water-closet into the trap of which the kitchen waste discharged, and into the dip of the running-trap of this horizontal soil-pipe, in the basement, and within a few feet of the furnace, was inserted a servants' hopper-closet without any flushing fixture; excremental matter being, of course, thus retained in the trap a great part of the time, and its decomposition favored by the admixture of hot water from the kitchen. When the water from the boiler was set running, the steam arose freely from this hopper. V. _Diphtheria._--Handsome country-seat. Plumbing work recently overhauled and declared perfect by the plumber. Three foul pan closets and numerous other "conveniences," all leading to unventilated cesspool. In the bedroom occupied by the patient the "safe-waste" from a stationary basin was carried into the soil-pipe, constituting a direct inlet from the cesspool. VI. _Diphtheria._--Presumably "first class" residence. Kitchen and laundry wastes carried from basement into privy-vault, which was filled to above the level of the pipes. VII. _Typhoid?_ (two irregular cases).--Cottage in good neighborhood. Bath and basin wastes discharging into trap of foul pan-closet with "putty-joints." Two inch tin pipe inserted, with leaky slip-joint, into bend of water closet trap, and carried with several angles to roof; no other ventilation of soil-pipe, which connects with leaching cesspool. Cellar riddled with rat-burrows (indicating probable connection with some old drain), and airbox of furnace made of loosely jointed boards, so as to convey the cellar air to upper part of house. VIII. _Typhoid?_ (continued fever)--Cottage on high ground. Offensive pan-closet on bedroom floor. Soil-pipe relieved by angular galvanized vent. But carried without other ventilation or trapping to cesspool on lower ground. Kitchen and laundry wastes untrapped and led to a row of buried barrels which were filled with a most malodorous mess, the water being allowed to soak into the soil as best it might. IX. _Diphtheria._--House without plumbing fixtures. Cellar loosely paved with bricks, and saturated with soakage from several privy-vaults on much higher ground and close in the rear; the fæcal-smelling semi-liquid filth actually oozing up between the bricks when they were stepped upon.