provement, a very considerable saving of fuel is effected from the immediate conversion of the whole, or very nearly the whole of the smoke arising from the fuel into flame: first, the said invention in principle consists in supplying the burning fuel more fully with air, having this fuel more in a body together, and a less quantity in combustion, at the same time, than what usually takes place in other furnaces, which are applied to the same uses; in applying the fuel with a portion of fresh air, admitted from an opening made for that purpose, and directed in such a manner as it may come in contact with the smoke from the kindling coal and great heat of the furnace together, and the fuel being more fully supplied with air, and consequently a greater degree of heat taking place, and the smoke and fresh air uniting in the great heat, the smoke is inflamed, and rendered useful in adding to the heat of the furnace; besides, this portion of fresh air is so conducted as to act partly on the kindling or kindled fuel, and raising it to a greater degree of heat, after it has served its purpose by uniting with and inflaming the smoke; and therefore is employed, in some measure, usefully, even after the coal has ceased to smoke: secondly, to the above may be added, the form of the furnace, which is so constructed, that the full kindled fuel is kept backward in the furnace, while the fresh coal lies before, and is more gradually kindled than if introduced further among the full kindled fuel, while the heat of the furnace is little injured or damped by the introduction of fresh coal, as is more fully described in the practical description of the furnace. The coal is admitted into the furnace by a hopper, feeder, or mouth-piece, A (Fig. 7 and 8), made of cast iron (but which may be made of other materials), and inclined to the horizon, as in Fig. 7; so that the coal in it, may in some measure, fall into the fire-place, above the bars, as the fuel is spent; in the in the upper part of this hopper, feeder, or mouth-piece, is a Plate, (Fig. 7 and 8), placed at a small distance, or from about three-eighths to three-fourths of an inch from the upper side of the hopper, betwixt which plate, and upper plate, or side of the hopper, a stream of air rushes downward on the fire, at about half a right-angle to the horizon, which stream of air assists in consuming the smoke, as formerly mentioned, and more fully described hereafter. B, Fig. 7, is a section of the bars, which are, in general, a little inclined to the horizon, as in the figure that the fuel may more easily fall, or be pushed backwards, in the furnace ; at c, is an opening above the bars, and below the lower end of the hopper, which is in general fitted with a grated door or doors, which open for the more convenient clean. sing of the furnace, and the grated form of the doors is also designed for admitting air into the fuel, as well as at the bars, consequently the air is more concentrated in the middle of the burning fuel, and produces a greater heat than if admitted only betwixt the bars; this grated form of the doors is also convenient for the admission of a poker or instrument for pushing backward the kindled fuel, while the fresh coal, or that which is not so well kindled, falls down to supply its place; in some others of these furnaces, the opening below the lower end of the hopper, and above the fore end of the bars, is left without doors at all; at this opening, it is convenient, when the fire is mended, to push the coal from the fore side backward, as mentioned above, or it may be pushed backward with a hooked poker, P, by applying the hooked part of it through the furnace bars below; by either of which means the kindled coals are put backwards, while the fresh coal, or that which is not so well kindled, falls down to supply their place; that is, the coals, in the situation c, are pushed towards d, while those in the situation ƒ fall down to supply the place of those which were driven from c towards d; by such means, the strength or heat of the fire is not much damped by the introduction of fresh coal, and the coals which have fallen from ƒ towards c, are not so rapidly kindled as if introduced above the burning fuel: same time the smoke which arises from these newly-introduced coals, passes partly through the full-kindled coal and partly over, and in contact with the great heat of the burning fuel, and, meeting at the same time with the current of fresh air coming downwards, and tending also to drive the smoke still nearer to the bright kindled fuel, does in general completely inflame the smoke, and render it useful in adding to the heat of the furnace. Another end obtained by the stream of fresh air, is to keep in some measure the great heat of the furnace from acting so violently on that part of the hopper which is nearest it, and mostly exposed to its heat, and liable to be damaged thereby, I which it does by the continual current of fresh cool air that is in contact with those parts; the construction of the furnace may be much varied; but the chief improvements are, that the fuel in combustion is supplied with air by the foreside as well as by the bars, the hopper is placed in such a situation that the kindled or unkindled coal may in part fall to the foreside of the furnace above the bars, as the other fuel is pushed backward in the furnace, and the admission of fresh air to pass over the burning fuel by means of a definite space or spaces, opening or openings, made for that purpose; so that this stream, current, or currents of air, partly come in contact with the burning fuel itself, forcing also the smoke with more immediate union with the burning fuel and great heat of the furnace. The Patentees do not pretend any claim to the admission of fresh air as a new principle, as they are sensible that this has been known long ago, and practised by admitting it at the furnace door, shutter, or mouth-piece, and at the opening where the coals are admitted into the furnace; their claim rests upon what has been formerly stated, together with the form of the furnace, and its variations after-mentioned; the success of the furnace depends also upon a considerable degree on what is called the draught of the furnace; that is, the chimney and flues so constructed, as a sufficient current of air may pass through the fire to bring it to a proper degree of heat; also, that the current of fresh air may have such force as to come pretty much in contact with the burning fuel, and to convey the smoke along with it through the hottest of the flame; if this is not the case, the smoke will not be so completely consumed in these furnaces. The hopper is allowed to be kept as full of coal as possible and either wholly or in part small coal, so as to prevent air as much as possible getting in by that passage; this must be attended to when the furnace is in its ordinary working state; yet, sometimes, it is necessary to keep. this opening of the hopper, either wholly, or in part, open, when there is little heat wanted. Description and reference to the draughts. Fig. 7, is a side view, or section of the furnace, as if applied to a boiler, and cut through the middle. Fig. 8, 15 a front view of the furnace in perspective, the hopper hay ing a division in the middle, and two regulating plates for the admission of fresh air. Figs. 7 and 8, A, the hopper into which the coals are put to supply the furnace, a the regulating plate; above which and below, the higher plate b of the hopper, a stream of fresh air is admitted to this plate; a is made to turn on a pin pivot or centre, so that it may be brought nearer to, or recede further from the uppermost at the point n, Fig. 7, for regulating the quantity of air admitted betwixt the plate as occasion requires; this plate is sometimes made fast, or kept so, after adopting a space which is judged sufficient for the quantity of fresh air but on other occasions, as in steam engines, it is |