Tiles are much used in some districts, and are often made of a pleasant tint; but a great objection to all tiles is their porosity, which causes them to absorb much water, rotting the woodwork and adding to their own already considerable weight. Metallic roofing embraces sheet copper, sheet zinc, sheet lead, “galvanised” iron, and thin plates of “rustless” (Bower-Barff) iron. These materials are only used on flat or nearly flat spaces. _Floors._--Tiles or flags are most frequently used for the floors of kitchens, sculleries, and lobbies. They serve this purpose very well, as they are easily washed and not likely to be injured, but the joints should be made impervious to moisture. In some parts of the country, concrete is used; this answers very well for the same purpose, but it is not good for bedrooms, as it is so cold to the feet. Wood makes the most comfortable floor for sitting or bed rooms, and the best is hard wood capable of bearing a polish. From its convenience and cheapness, common deal is used very generally, and too often in a damp and unsound state, so that the boards shrink and wide gaps are left between. This allows all the foul air from any space--as a cellar or a cavity between the floor and the soil--to ascend into the room. The boards ought to be as close together as possible, and any spaces left between them should be packed tightly with oakum. If this is done, the floors may be stained and varnished, when they can be swept and rubbed clean, and do not require such frequent washing as the ordinary unvarnished floors. This is an important gain, for there is no doubt that emanations rising with the damp from newly-washed floors are often most injurious. If a varnished floor is washed, it dries almost at once. Spaces must be left under the floors, on the ground level, if they are of wood, or they will soon decay; and they ought to be well ventilated. Ceilings, leaving a space between them and the boards of the room above, have come into use, most likely to deaden sound. They often fail of this, while affording fine playgrounds to mice, and even rats. Well-laid boards, of sufficient thickness, and plugged with oakum, would, as regards health, be preferable. (Dr. Simpson.)