Allied with fireplaces, but still more important in their relations to household life, are the stoves and furnaces with which every house is provided. All these consist essentially of an iron fire-box, under which is a grate, made with openings large enough to allow ashes to fall through, and air, for sustaining combustion, to pass in, but not large enough to allow the un-burnt coal to escape. The smoke and flame from the fire-box, after describing a path more or less circuitous, are drawn off through an iron smoke-pipe into the chimney. In ordinary airtight heating stoves the smoke usually passes directly from the fire-box into the chimney; but, in order to increase its effect in warming the room, the iron pipe, instead of entering the chimney by the shortest path, is often carried up nearly to the ceiling, increasing by so much the heating surface. In stoves of this kind, control over the fire is obtained by means of a damper in the smoke-pipe, and two slides, one in the upper door of the stove, through which coal is put on the fire, and the other in the lower door, through which ashes are removed from the ashpit below the grate. To increase the combustion the upper slide is closed, and the lower one opened; while, to check the fire, the lower slide is closed, and the upper one opened. The reason why opening the lower slide intensifies the fire is that air is thereby admitted through the grate to the burning coal above it. In general, combustion is proportional to the amount of oxygen which reaches the fuel, as may be seen by blowing air among the logs of a wood fire; but the admission of air to the fire from under the grate serves an additional purpose, in that the heat from the quickened combustion of the lower layer of coal rises through the fresh coal above, causing it also to kindle. If, at the same time, the upper slide is kept closed, the air which ascends from underneath through the entire body of burning coal enters the chimney intensely heated; and, as the upward current in a chimney of given dimensions is proportional to the temperature of the smoke and heated gases in it, a strong draught is thereby established, which increases the amount of air drawn through the fire, and still further intensifies combustion. If, on the contrary, the upper slide is opened, cold air is drawn in above the fire, and, mixing with the hot smoke and gases from the fire, reduces their temperature just as they enter the chimney, and proportionally diminishes the draught in the chimney, and, in consequence, the rapidity with which air is drawn up from below through the fire. The powerful effect of opening the upper slide in checking the fire may be understood by supposing the upper and lower slide to be of the same size, and both to be open at the same time. Assuming the current of air from the lower slide to lose half its velocity in finding its way among the coals and cinders in the burning mass, this hot current, before entering the chimney, would be mixed with twice its volume of cold air from the upper slide, and the excess of temperature over that of the external atmosphere, to which the draught is due, would be only one-third as great as that of the air derived from the lower slide alone. This amounts to cutting off two-thirds of the draught in the chimney, with a proportionate reduction in the intensity of the fire; and if, as is usual, the lower slide is closed, at the same time that the upper one is opened, the combustion is further reduced to an indefinite extent, as it is then maintained only by such air as may leak in through the joints of the door and slide to the space under the grate. With stoves of the simplest kind, the damper in the smoke-pipe may be wholly or partly closed, to reduce the volume of heated air passing into the chimney, and thereby again check the draught, and the combustion; but, on account of the danger of driving gas into the room if the smoke-pipe is completely obstructed, the damper is usually made with a notch, or hole, sufficient to carry off the smoke from a small fire.

By means of the upper and lower slides, and the damper in the smoke-pipe, very extensive control is obtained over a fire in a closed stove or furnace, and the same principle is applied to nearly all forms of heating apparatus. In open stoves, "Baltimore heaters," and open grates, for either hard or soft coal, the place of the upper slide is taken by a "blower," which is either entirely removable, or is attached, in the shape of a "curtain," which slides up and down. So long as the stove or grate is open, an immense quantity of cold air is drawn in from the room over the fire, which mixes with the smoke and gases before they enter the chimney, chilling them, and proportionately reducing the draught; but, by putting on the blower, or pulling down the curtain, the current of cold air drawn from the room above the fire is cut off, and all the air drawn into the chimney must come up from below, through the fire, thus quickening the combustion of the whole mass of fuel and greatly increasing the draught in the chimney. With ordinary grates, where there is no way of controlling the admission of air below the fire, the blower can only be kept on for a few minutes without danger of melting the grate; but most open stoves, and fireplace heaters of the Baltimore type, have a movable piece, containing a slide, which fits closely against the grate, and, by applying this, and using the slide for controlling the admission of air below, the blower can be kept on, and the apparatus virtually converted into a close stove.

Two varieties of stoves should be mentioned before passing to more complicated apparatus; these being the base-burner and the jacketed stove. The base-burner differs from an ordinary stove simply in having an iron cylinder set in the upper portion, forming a reservoir of coal, which can be filled from the top. As the coal in the fire-box is consumed, a fresh supply descends by gravitation from the reservoir, so that frequent feeding is avoided; and, as the smoke-pipe is taken from the fire-box, outside the coal-cylinder, and this is provided with an iron cover, there is no danger that the coal in it will take fire.

The jacketed stove, which is not so widely used as it should be, consists, substantially, of an ordinary stove, either open or closed, surrounded by an iron casing, at a little distance from the walls of the stove proper. The feeding and ash doors extend to the outer casing, and an ornamental open iron top usually covers the whole. In the cheaper forms, which are often used for heating country schoolhouses, the outer casing extends only to within three or four inches of the floor, so that air is drawn in below the edge of the casing, and rises through the space between the casing and the stove, becoming heated in its journey by contact with the stove on one side and the casing on the other, and finally escapes through the openwork of the top. This circulation of air adds greatly to the heating power of the stove, and an extemporaneous casing of the sort may often be placed around an ordinary stove with advantage. A much more perfect arrangement, however, consists in supplying the space between the stove and the casing with fresh air from out of doors, which can be brought in through a pipe, warmed, and discharged into the room through the openwork top of the stove, giving admirable ventilation, which is still further improved when, as is the case with certain sorts, the stove itself can be used as an open stove, drawing in the warmed air, after it has made the circuit of the room, and thus maintaining a constant circulation. For a children's nursery, where an abundant supply of pure, warm air, and an open fire, not only for its cheerful and health-giving radiation, but for drying and warming clothing, and heating saucepans, are absolute essentials, no apparatus ever devised approaches these stoves.

Base-burners.

Jacketed stoves.

D bright tin, to reflect the heat, can be roasted by direct radiation from the fire, instead of being shut up in the regular oven. This arrangement has, however, the disadvantage of keeping the front of the stove or range very hot; and, with modern stoves, in which air is allowed access to the oven while roasting or baking are going on, the difference in flavor of meat cooked in the oven or before the fire is mainly imaginary.