however, be considerably less than the inlet, or it will produce draughts.
18. The inlet, on the contrary, should be as capacious as possible; because it has to provide not only for the outlet in the ceiling, but also for the chimney, and that when the fire is burning and requiring for its supply alone from 600 to 1,000 cubic feet per minute. Indeed, the inlet should be able to admit more air than can possibly find its way out by both these outlets, otherwise it will produce draughts. When the air can get out of an apartment more rapidly than it can come in, there are sure to be currents; but when more air can come in than can get out—when the air has to go out under pressure, so to speak—there will be little or no current. And the inlet should be through the wall of the opposite side of the room to the fireplace; because the fire will then draw the air into and across the room, and thus cause it to circulate throughout the whole of the apartment. If the fireplace be on the same side as the inlet, it will not only not assist to circulate the air throughout the apartment, but it will prevent it from so circulating by drawing it directly up the smoke-flue; and it should, moreover, be split up into as many divisions as possible, so as to distribute the supply along the whole side of the room, and thus assist to prevent any perceptible current; and this will be further helped by having the openings through the cornice instead of through the skirting, because then the fresh air will be the warmest that is in the corridor, and it will also have to descend through the warmer air of the room before it can come in contact with the persons therein. When through the skirting, it is the coldest air of the corridor; it comes through the coldest air of the room, and it comes first to the part of the body where it can least be borne, viz., the feet.
In this country (England) it is necessary to provide specially for ventilation. In consequence of the nature of our climate, the doors or windows can very seldom be left open, even in the day, and never in the night, without risk. Indeed, no direct admission of the external air into the apartments of the house can be endured during at least eight or nine months of the year—in fact, the great prevalence of cold, searching, and shriveling east wind renders such an admission absolutely dangerous; so that no kind of arrangement of openings directly to the out-of-doors air, such as drawing down the window-sash, perforated bricks or gratings in the wall, perforated or louvered square in the window, the wire-gauze at the top of the window-sash, patent ventilators, or any other contrivance that communicates directly with the out-of-doors air, can possibly answer for ventilation in a country like ours. In this country, where eight or nine out of the twelve months in the year are cold, windy, and winterly, houses should be built with reference to winter, and not with reference to summer; and they should be planned and built with the object of keeping out the cold air and not with the object of letting it in; ventilation should be pro-