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time, very little is done by these chimneys to- | ing warms the air in those cavities which is wards warming the room; for the air round continually coming into the room fresh and the fire-place, which is warmed by the direct warm. The invention was very ingenious, rays from the fire, does not continue in the and had many inconveniences: the room was room, but is continually crowded and gather- warmed in all parts, by the air flowing into it ed into the chimney by the current of cold through the heated cavities: cold air was air coming behind it, and so is presently car- prevented rushing through the crevices, the ried off. funnel being sufficiently supplied by those caIn both these sorts of fire-places, the great-vities: much less fuel would serve, &c. est part of the heat from the fire is lost; for as fire naturally darts heat every way, the back, the two jambs, and the hearth, drink up almost all that is given them, very little being reflected from bodies so dark, porous, and unpolished; and the upright heat, which is by far the greatest, flies directly up the chimney. Thus five sixths at least of the heat (and consequently of the fuel) is wasted, and contributes nothing towards warming the room.

3. To remedy this, the sieur Gauger gives, in his book entitled, La Mechanique de Feu, published in 1709, seven different constructions of the third sort of chimneys mentioned above, in which there are hollow cavities made by iron plates in the back, jambs, and hearths, through which plates the heat pass

first case, the shock the body endures, is general, uniform, and therefore less fierce; in the other, a single part, a neck, or ear perchance, is attacked, and that with the greater violence probably, as it is done by a successive stream of cold air. And the cannon of a battery, pointed against a single part of a bastion, will easier make a breach than were they directed to play

singly upon the whole face, and will admit an enemy much sooner into the town."

That warm rooms, and keeping the body warm in winter, are means of preventing such diseases, take the opinion of that learned Italian physician Antonino Parcio, in the preface to his tract de Militis Sanitate tu enda, where speaking of a particular wet and cold winter, remarkable at Venice for its sickliness, he says,

*Popularis autem pleuritis quæ Venetiis sæviit mensibus Dec. Jan. Feb. ex cæli, aërisque inclementia facta est, quod non habeant hypocausta [stove-rooms] et quod non soliciti sunt Itali omnes de auribus, temporibus, collo, totoque corpore defendendis ab injuriis aëris; et tegmina domorum Veneti disponant parum inclinata, ut nives diutius permaneant super tegmina. E contra, Germani, qui experiuntur cæli inclementiam, perdidi cere sese defendere ob acris injuria. Tecta construunt multum inclinata, ut decidant nives. Germani abundant lignis, domusque hypocaustis; foris autem incedunt pannis pellibus, gossipio, bene mehercule loricati atque muniti. In Bavaria interrogabam (curiositate motus videndi Germaniam) quot nam elapsis mensibus pleuritide vel peripneumonia fuissent absumti: dice. bant vix unus aut alter illis temporibus pleuritide fuit

correptus.

The great Dr. Boerhaave, whose authority alone might be sufficient, in his Aphorisms, mentions, as one antecedent cause of pleurisies, "A cold air, driven violently through some narrow passage upon the body,

overheated by labour or fire."

The eastern physicians agree with the Europeans in this point; witness the Chinese treatise entitled, Tschang seng; i. e. The Art of procuring Health and Long Life, as translated in Pere Du Halde's account of China, which has this passage. "As, of all the passions which ruffle us, anger does the most mischief,so of all malignant affections of the air, a wind that comes through any narrow passage, which is cold and piercing, is most dangerous; and coming upon us unawares insinuates itself into the body, often causing grievous diseases. It should therefore be avoided, according to the advice of the ancient proverb, as carefully as the point of an arrow." These mischiefs are avoided by the use of the new-invented fire-places, as will be shown hereafter.

the first expense, which was very great, the intricacy of the design, and the difficulty of the execution, especially in old chimneys, discouraged the propagation of the invention; so that there are, I suppose, very few such chimneys now in use. The upright heat, too, was almost all lost in these, as in the common chimneys.

The

4. The Holland iron stove, which has a flue proceeding from the top, and a small iron door opening into the room, comes next to be considered. Its conveniences are, that it makes a room all over warm; for the chimney being wholly closed, except the flue of the stove, very little air is required to supply that, and therefore not much rushes in at crevices, or at the door when it is opened. Little fuel serves, the heat being almost all saved; for it rays out almost equally from the four sides, the bottom and the top, into the room, and presently warms the air around it, which, being rarefied, rises to the ceiling, and its place is supplied by the lower air of the room, which flows gradually towards the stove, and is there warmed, and rises in its turn, so that there is a continual circulation till all the air in the room is warmed. air, too, is gradually changed, by the stovedoor's being in the room, through which part of it is continually passing, and that makes these stoves wholesomer, or at least pleasanter than the German stoves, next to be spoken of. But they have these inconveniences. There is no sight of the fire, which is in itself a pleasant thing. One cannot conveniently make any other use of the fire but that of warming the room. When the room is warm, people, not seeing the fire, are apt to forget supplying it with fuel till it is almost out, then growing cold, a great deal of wood is put in, which soon makes it too hot. The change of air is not carried on quite quick enough, so that if any smoke or ill smell happens in the room, it is a long time before it is discharged. For these reasons the Holland stove has not obtained much among the English (who love the sight of the fire) unless in some workshops, where people are obliged to sit near windows for the light, and in such places they have been found of good use.

5. The German stove is like a box, one side Wanting. It is composed of five iron plates screwed together, and fixed so as that you may put the fuel into it from another room, or from the outside of the house. It is a kind

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(ii.) The back plate is without holes, having only a pair of ledges on each side, to receive the back edges of the two.

of oven reversed, its mouth being without, | edges of the back plate, the two side plates, and body within the room that is to be warm- and the two middle plates. These ledges are ed by it. This invention certainly warms a about an inch asunder, and about half an room very speedily and thoroughly with little inch high; a profile of two of them, joined to a fuel: no quantity of cold air comes in at any fragment of plate, appears in Fig. 3. crevice, because there is no discharge of air which it might supply, there being no passage into the stove from the room. These are its conveniences. Its inconveniences are, that (iii iii.) Side plates: these have each a people have not even so much sight or use of pair of ledges to receive the side edges of the the fire as in the Holland stoves, and are, front plate, and a little shoulder for it to rest moreover, obliged to breathe the same un-on; also two pair of ledges to receive the side changed air continually, mixed with the breath and perspiration from one another's bodies, which is very disagreeable to those who have not been accustomed to it.

6. Charcoal fires in pots are used chiefly in the shops of handicraftsmen. They warm a room (that is kept close, and has no chimney to carry off the warmed air) very speedily and uniformly; but there being no draught to change the air, the sulphurous fumes from the coals, [be they ever so well kindled before they are brought in, there will be some,] mix with it, render it disagreeable, hurtful to some constitutions, and sometimes, when the door is long kept shut, produce fatal consequences. To avoid the several inconveniences, and at the same time retain all the advantages of other fire-places, was contrived the Pennsylvanian fire place, now to be described.

This machine consists of

A bottom plate, (i) (See the plate annexed.)

Á back plate, (ii)

Two side plates, (iii iii)

Two middle plates, (iv iv) which, joined together, form a tight box, with winding passages in it for warming the air.

A front plate, (v)
A top plate, (vi.)

These are all cast of iron, with mouldings or ledges where the plates come together, to hold them fast, and retain the mortar used for pointing to make tight joints. When the plates are all in their places, a pair of slender rods, with screws, are sufficient to bind the whole very firmly together, as it appears in Fig. 2.

There are, moreover, two thin plates of wrought iron, viz. the shutter, (vii) and the register, (viii;) besides the screw-rods O P, all which we shall explain in their order.

(i.) The bottom plate, or hearth-piece, is round before, with a rising moulding, that serves as a fender to keep coals and ashes from coming to the floor, &c. It has two ears, FG, perforated to receive the screw rods O P; a long air-hole, a a, through which the fresh outward air passes up into the air box; and three smoke holes B ̊C, through which the smoke descends and passes away; all represented by dark squares. It has also double ledges to receive between them the bottom

edges of the two middle plates which form the air box; and an oblong air-hole near the top, through which is discharged into the room the air warmed in the air-box. Each has also a wing or bracket, H and I, to keep in falling brands, coals, &c. and a small hole, Q and R, for the axis of the register to turn in.

(iv iv.) The air-box is composed of the two middle plates, D E and F G. The first has five thin ledges or partitions cast on it, two inches deep, the edges of which are received in so many pair of ledges cast in the other.The tops of all the cavities formed by these thin deep ledges, are also covered by a ledge of the same form and depth, cast with them; so that when the plates are put together, and the joints luted, there is no communication between the air-box and the smoke. In the winding passages of this box, fresh air is warmed as it passes into the room.

(v.) The front plate is arched on the under side, and ornamented with foliages, &c. it has no ledges.

(vi.) The top plate has a pair of ears, M N, answerable to those in the bottom plate, and perforated for the same purpose: it has also a pair of ledges running round the under side to receive the top edges of the front, back, and side plates. The air-box does not reach up to the top plate by two inches and a half.

(vii.) The shutter is of thin wrought iron and light, of such a length and breadth as to close well the opening of the fire-place. It is used to blow up the fire, and to shut up and secure it at nights. It has two brass knobs for handles, d d, and commonly slides up and and down in a groove, left, in putting up the fire-place, between the foremost ledge of the side plates, and the face of the front plate; but some choose to set it aside when it is not in use, and apply it on occasion.

(viii.) The register is also of thin wrought iron. It is placed between the back plate and air-box, and can, by means of the key S, be turned on its axis so as to lie in any position between level and upright.

The screw-rods O P are of wrought iron, about a third of an inch thick, with a button at bottom, and a screw and nut at top, and may be ornamented with two small brasses screwed on above the nuts.

To put this machine to work,

1. A false back of four inch (or, in shallowing specifically lighter than the other air in small chimneys, two inch) brick work is to be the room, is obliged to rise; but the closure made in the chimney, four inches or more from over the fire-place hindering it from going up the true back: from the top of this false back the chimney, it is forced out into the room, a closing is to be made over to the breast of rises by the mantle-piece to the ceiling, and the chimney, that no air may pass into the spreads all over the top of the room, whence chimney, but what goes under the false back, being crowded down gradually by the stream and up behind it. of newly-warmed air that follows and rises above it, the whole room becomes in a short time equally warmed.

2. Some bricks of the hearth are to be taken up, to form a hollow under the bottom plate; across which hollow runs a thin tight partition, to keep apart the air entering the hollow and the smoke; and is therefore placed between the air-hole and smoke-holes.

3. A passage is made, communicating with the outward air, to introduce that air into the forepart of the hollow under the bottom plate, whence it may rise through the air-hole into the air-box.

4. A passage is made from the back part of the hollow, communicating with the flue behind the false back: through this passage the smoke is to pass.

The fire-place is to be erected upon these hollows, by putting all the plates in their places, and screwing them together.

Its operation may be conceived by observing the plate entitled, Profile of the Chimney and Fire-place.

At the same time the air, warmed under the bottom plate, and in the air-box, rises and comes out of the holes in the side-plates, very swiftly, if the door of the room be shut, and joins its current with the stream before-mentioned, rising from the side, back, and top plates.

The air that enters the room through the air-box is fresh, though warm; and, computing the swiftness of its motion with the areas of the holes, it is found that near ten barrels of fresh air are hourly introduced by the airbox; and by this means the air in the room is continually changed, and kept, at the same time, sweet and warm.

It is to be observed, that the entering air will not be warm at first lighting the fire, but heats gradually as the fire increases.

M The mantle-piece, or breast of the chim-left in the closing of the chimney, for the

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D The air-box.

A square opening for a trap-door should be sweeper to go up: the door may be made of slate or tin, and commonly kept close shut, but so placed as that, turning up against the back of the chimney when open, it closes the vacancy behind the false back, and shoots the soot, that falls in sweeping, out upon the hearth. This trap-door is a very convenient thing.

K The hole in the side-plate, through which In rooms where much smoking of tobacco is the warmed air is discharged out of the air-used, it is also convenient to have a small box into the room.

H The hollow filled with fresh air, entering at the passage 1, and ascending into the airbox through the air-hole in the bottom plate

near.

G The partition in the hollow to keep the air and smoke apart.

P The passage under the false back and part of the hearth for the smoke.

The arrows show the course of the smoke. The fire being made at A, the flame and smoke will ascend and strike the top T, which will thereby receive a considerable heat. The smoke, finding no passage upwards, turns over the top of the air-box, and descends between it and the back plate to the holes in the bottom plate, heating, as it passes, both plates of the air-box, and the said back plate; the front plate, bottom and side plates are also all heated at the same time. The smoke proceeds in the passage that leads it under and behind the false back, and so rises into the chimney. The air of the room, warmed behind the back plate, and by the sides, front, and top plates, becom

hole, about five or six inches square, cut near the ceiling through into the funnel: this hole must have a shutter, by which it may be closed or opened at pleasure. When open, there will be a strong draught of air through it into the chimney, which will presently carry off a cloud of smoke, and keep the room clear; if the room be too hot likewise, it will carry off as much of the warm air as you please, and then you may stop it entirely, or in part, as you think fit. By this means it is, that the tobacco smoke does not descend among the heads of the company near the fire, as it must do before it can get into common chimneys.

The manner of using this Fire-place.

Your cord-wood must be cut into three lengths; or else a short piece, fit for the fireplace, cut off, and the longer left for the kitchen or other fires. Dry hickory, or ash, or any woods that burn with a clear flame are rather to be chosen, because such are less apt to foul the smoke-passages with soot: and flame communicates with its light, as well as by contact,

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