Now although scientific plumbers have done good work in making our dwellings more healthy, they have in many cases overdone the matter. The fact of their displaying conspicuously, on signs and billheads, “Sanitary work executed on the most scientific principles,” is not always a guarantee that a healthy house can be received from their hands. In the house above referred to, everything to the eye appeared sound and good, but on the house being occupied, a disagreeable odour was noticed in the kitchen, and in some of the lower rooms. The sink-pipe, which was pointed out by the builder as being “cut off,” ran from the sink trough without a trap or water-seal of any kind, and through this pipe, when the doors were shut, the air was supplied to the building at the rate of 180 feet per minute. The back of the W.C. was ventilated from the outside to give free ventilation to the space under the seat, and through the ventilators (which were working as inlets) the air came into the house, which supplied the bedrooms, passing over the pan, between it and the seat. The above is an illustration of a house where the sanitary arrangements were supposed to be on the most scientific principles! Fresh air being supplied to bedrooms by passing over the closet-pan, and in the kitchen and rooms below by passing through a 2-inch sink-pipe. This is one of the many cases that may be mentioned to show the necessity of testing any system of drainage and sanitary fittings. This is not an unusual occurrence, as thousands of similar cases exist, where the principal air supply passes over sanitary fittings or through apertures which bring it in contact more or less with decomposed matter. In a building where a number of fireplaces exist, a constant current of air is passing in from the outside, which after mixing with the air in the building escapes up the chimney. An ordinary chimney extracts from the room from 60 to 120 cubic feet of air per minute, thus in a ten-roomed house you have going out of the chimneys at least 1000 cubic feet of air per minute. When the house is closed this large volume of air is drawn into it through apertures offering the least resistance, whether it be ventilators in the w.c., kitchen sinks, or drains in the basement (which traps may have been siphoned), over sanitary pipes or through doors and windows. Whichever point offers the least resistance, there the supply to feed the chimneys will come.