tical for theorists, and in its results too philosophical for "practical men."
A grid with a clear opening of two to two and a half feet square, through which air is sent at the rate of three feet per second, will change the entire atmosphere of an ordinary London house every hour; and a good-sized coke or well-constructed German stove will heat this volume of air from 65° to 70°, and maintain a temperature throughout such house of 50° to 55°.
The bulk of the heat so generated will be utilized and diffused. The excessive loss of heat from fireplaces will be changed to use, and economy will be the rule instead of a waste—excessive, continuous, and expensive. And the whole of it will be in substitution—not in excess—of an undisturbed open fire-grate consumption of fuel, and this by a process of natural selection and persuasion. With a fairly equable temperature of 50° to 55° throughout the house, and highest where now it is usually lowest—the hall and passages—the demand for large open fires subsides. Small fires become the rule, and their going out the difficulty. There will be no dread of draughts from open doors; no peevish injunctions to "shut that door;" no huddling over a hot fire, scorched on one side and chilled on the other; no breathing at one moment of air at 100°, and the next, and without preparation or much gradation, one of 40°. In short, "the bull will be taken by the horns" and tamed. We have made friends of our foes, and we may cry Eureka!—for the problem will be solved!
Now for the possible objections. We shall probably be told that stoves are unwholesome—that they spoil the air and make the warmed space "close." Our reply is, that stoves in unventilated rooms do all this, and more. They are usually unsightly, and they—even the most economical—rob the room of the bright, cheerful, moral influence of warmth with light. But none of the objections to which stoves are liable attach to their use under the arrangement we advocate. The stove is not placed in an unventilated room, but in a strong draught. No particle of air ever gets warmed twice over. None is forced into contiguity with the heating surface. It takes up as it passes that surface its modicum of caloric, and wings it way to impart it to all and everything of a lower temperature than itself; and finally it escapes, when fairly deprived of it, by nicks and crannies and illegitimate outlets, as well as by those prearranged for the best effect. Hence there are no whistling shreds of frosty air, harbingers of colds, catarrhs, toothache, earache, and neuralgic inflictions; no "sulphuring" from down-draughts in unused bedroom-fires; no shiversome "draughts" from open doors. By admitting air round about our heat-generator, full, free, and unconfined, we adopt the principle of the steam-engine governor. If the stove be overheated from negligence, the draught becomes quicker, the particles of air are heated sooner, but not necessarily much more. If the stove-fire is allowed to get low, each par-
