HEATING AND VENTILATION. C91 HEATING AND VENTILATION. involves the bringing in of air varncd liy pass- ing it over some central heated suiface, generally a furnace, but sometimes a coil of steam or hot- water pipes. It will be noted that direct radia- tion heats the air already in the room, while indirect radiation brings in healed air. Thus, indirect radiation may be a means of ventilation, also, by seeing that pure air is secured for heat- ing and distribution. The same end may be ellected by locating the heating surface in the room and passing the fresh air over it, which is known as direct-indirect radiation. Strictly speaking, fireplaces only heat solely by direct radiation, i.e. by sending the heat out in straight lines until it is deflected or absorbed by some- thing other than air. With stoves and radiators most of the heat is made available by con- vection, i.e. by heating the air that impinges upon or passes over the heated surface. History. The first application of artificial heat consisted, most likely, in lighting a fire of dried sticks and leaves in a grove, a cave, or other natural shelter. Where tents or wigwams came to be erected, the fire would be lighted ou the middle of the floor, with perhaps a hole in the roof for smoke to escape. The Romans V armed their apartments chiefly by portable stoves, without any regular exit for the smoke and fumes. A brazier of charcoal is still the chief means of heating sitting-rooms in houses in Spain and Italy, which are in general without chimneys, which are comparatively a modern in- vention. The early fireplaces were without chim- neys and the flues extended only a few feet up in the thickness of the wall. They were then turned out through the wall, to the back of the fli'e- place, the openings into the outer air being small oblong holes. There is no evidence of chunneys earliei- than the twelfth century, and brick was not used for their construction till late in the fifteenth century. Of the modern methods of heating dwellings by fireplaces, stoves, furnaces, steam and hot-air apparatus, the fireplace is the oldest, having been employed during the Middle Ages, and becoming, in Xorthern Europe, an important feature of the architectural de- velopment. The fireplace, at first wholly of masonry, was afterwards framed in elaborately carved oak, and the settle, which soon became an essential part of mediieval furniture, was built into the angle of the chimney. Stoves are said to have been used for the first time in Alsace, in 1490, but they did not come into general use as a means of heating until three centuries later. In 1744 Benjamin Franklin invented a cast-iron open heater, which projected out from the chim- ney, and so radiated heat into the room from the back and sides as well as from the front. The east-iron box stove was invented in 1752. Early in the nineteenth century cylindrical sheet-iron stoves were made. About 1830 the first base- burner was put upon the market in America, and since that time the different types of stoves have been developed, by successive patents, to their present state of perfection. The first attempt to construct a liotair fur- nace for supplying pure heated air to rooms was probably made by Franklin. In 1744 he built a box-shaped stove for bui-ning wood. "The smoke escaped over the top of a flat chamber behind its fire, passing downward between it and the real back of the stove, and thence into the chimney. This flat, hollow chamber communi- cated underneath the stove with a tube opening into the external atmosphere, and a quantity of air was thus passed through the Hat chamber into the room through small holes left in the sides." Early in the nineteenth century the method of warming by hot air was developed. The first hot-air furnace in New England is said to have been built in Worcester, Mass., in 1835. Heating by hot water was an invention of great antiquity. According to Seneca, the baths of Rome were warmed by water running through brass pipes, which at one point were heated in a fire. W'ith the fall of Rome this method of warming the air seems to have been forgotten, for we next hear of it as a fresh discovery made in 1777 by M. Bounemain for warming the hot- houses of the Jardin des Plants in Paris. Heat- ing by hot water was introduced into England in 1816 by the ilarquis de Chabonne. It was used in Canada for many years before it became popular in the United States, where it was not generally adopted till the last quarter of the nineteenth century. Heating by steam was pro- posed, in the middle of the eighteenth century, by ^■illianl Cook, of Manchester, England. In the United States it was not introduced till nearly a century later. The first building in America warmed in this way was the Eastern Hotel of Boston, and the first factory the Bur- lington Woolen Mill, Vermont. FiKEPLACES. Tile open fire glowing in a grate, which is still the prevalent mode of warming dwelling-houses in Great Britain, and the more common wood fire in America, have an air of cheerfulness and comfort that make them almost objects of worship. Unfortunately, only 10 to 25 per cent, of the value of the fuel burned in fireplaces is utilized as heat; such fires give a partial kind of warmth, heating the side of the body next to them, but leaving the rest cold, and producing draughts into the rooms which are anything but safe or agreeable. Nevertheless, the fireplace holds its own, for besides its cheer- fulness and sentimental features it is, or may be, ornamental, while as an eflficient aid to ven- tilation it is most useful. The substitution of brick-lined for non-lined fireplaces conserves some of the heat. Much also depends upon the shape of the fire-box, or grate itself, where coal, rather than wood, is burned. The chief object is to present as large a surface as possible of glowing fire to the front in order to secure as much radiant heat as possible. With this view, the grate is made long and deep, in proportion to its width from front to back. This principle, however, is carried too far in many grates. The stratum of fuel is too thin to burn perfectly, especially in the narrow angles at the sides, where the coal seldom gets to a red heat, and is only warm enough to distill away in smoke. Such fires are constantly going out, and are further from being economical than a square box. Placing grates almost on a level with the floor is a mistake. The floor and the lower part of the person receive no share of the radiant heat. The chimney throat, instead of a gulf drawing in a constant wide current of the warm air of the room, and causing draughts from windows and doors toward the fireplace, should just be sufli- cient to admit the burned gases and smoke. Fire- places are sometimes so arranged in connection with an air-inlet as to introduce a current of
