STOVES for heating Rooms. The most simple contrivance of this kind is that described by Dr Lewis in his Commercium Philosophico-technicum. He there recommends the two crucibles which he makes use of for a chemical furnace*, the one inverted over the other, and the joining secured by a hoop. These
furnaces, says he, may be used likewise as a common stove, for keeping a room warm with a little quantity of fuel.—There are three general intentions which have been pursued in contrivances for this purpose:
1. Making the fuel take fire by degrees, and consume slowly; 2. conducting its heat, or the air warmed by it, through a number of passages or circumvolutions, that the heat, instead of being carried up the chimney and thus lost, may be detained in these passages, and thence communicated to the air of the room to which they lie exposed; and, 3. applying to the fire a quantity of solid matter, which, being once heated, preserves its heat long. Some ingenious furnaces, on these principles, are described in the Transactions of the Swedish academy, and in the second edition of Reaumur's Art of hatching Birds. All these contrivances are united in the following combination of the two pots and the hoop.
The undermost pot has the small grate introduced into its lower part, the fire-place door closed, and the ash-pit door or the bottom hole open for admitting air. Being then charged with small pieces of charcoal, and some lighted coals thrown above them, its top is covered by the largest of the grates; and on this is placed the hoop and dome, filled with balls of baked earth, or with pieces of bricks, so disposed as to leave small vacuities between them. If the stove is placed in the middle of a room, its injurious burnt air may be carried off by a pipe inserted laterally into the larger door of the dome, and communicating at the other end, which should be raised eight or ten inches, with the chimney of the room; all the other apertures of the dome being closed.
The furnace thus charged, will keep up a moderate and nearly equal warmth for many hours, without injury or offence; the charcoal burning down exceedingly slowly, and the heated balls or bricks continuing the warmth for a considerable time after the fuel is consumed. Fresh charcoal may be occasionally supplied.
Stourbridge plied through the door above the grate: the check which the balls give to the motion of the air through the furnace renders the consumption of this also slow; and it may still be made more so at pleasure, by stopping a part of the aperture which admits the air, or of the pipe or chimney which carries it off.