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'he true back of the chimney ; E the top of the fire-place ; F thefront of it; A the place where the fire is made ; D the air-box ;K the hole in the side plate, through which the warmed air is dis-charged out of the air-box into the room ; II the hollow, formedby removing some bricks from the hearth under the bottom platetilled with fresh air, entering at the passage I, and ascending intothe air-box through the air-hole in the bottom plate near G, thepartition in the hollow, designed to keep the air and smoke apart;P the passage under the false back, and part of the hearth for thesmoke. The arrows shew the course of the smoke. The fire be-ing made at A, the flame and smoke will ascend, strike the topT, and give it a considerable heat; the smoke will turn over theair-box, and descend between it and the back plate to the holesnear G in the bottom plate, heating in its passages all the plates ofthe machine ; it will then proceed under and behind tire falseback, and rise into the chimney. The air of the room contiguousto the several plates, and warmed by them, becomes specificallylighter than the other air in the room, and is obliged to rise ; butbeing prevented by tiie closure over the fire-place from going upthe chimney, is forced out into the room, and rising by the man-tle-piece to the ceiling, is again driven down gradually by thesteam of newly warmed air that follows: and thus the whole roombecomes in a little time equally wanned. The air also, warmedunder the bottom plate and in the air-box, rises and comes out ofthe holes in the side plates, thus warming and continually changingthe air of the room, in the closing of the chimney a square open-ing for a trap door should be left for the sweeper to go up : thedoor may be made of slate or tin, and so placed, that by' turningup against the back of the chimney when open, it closes the va-cancy behind the false back, and shoots the soot that falls in sweep-ing out upon the hearth. It will also be convenient to have asmall hole, about five or six inches square, cut near the ceilingthrough into the funnel, and provided with a shutter; by occa-sionally opening which, the heated air of the’room and smoke oftobacco, &c. may be carried off without incommoding the com-pany. For a further account of the manner of fixing and usingthis fire-place, see Franklin’s Letters aud Papers on Philosophi-cal Subjects, p. 2S4—318, edit. 1769.

Fire-Places, Count Rumsord’s Improvements of. Theingenious Count Rumford has lately published a valuable Essayon the most beneficial form in which common fire-place6 may beconstructed ; so as not only to prevent smoking, but also to im-prove them in all other respects. See Smoking,

Fire-Pots, in the military art, small earthen pots, into whichis put a charged grenade, and over that powder enough to coverthe grenade; then the pot is covered with a piece of parchment,aud two pieces of match across lighted : this piece being thrown bya handle of matches where it is designed, it breaks and fires thepowder, and burns all that is near it, and likewise fires the powderin the grenade, which ought to have no fuse, that its operationsmay be the quicker.

Fire-Reeds, reeds used in fire-ships. They are made up insmall bundles of about a foot in circumference, cut even at bothends, and tied together in two places. They are distinguishedinto two kinds, via. the long and short; the former of which arefour feet, and the latter two feet five inches in length. One partof them are singly dipped, i. e. at one end ; the rest are dipped atboth ends in a kettle of melted composition, Alter being im-mersed about seven or eight inches in this preparation, and thendrained, they are sprinkled over with pulverised sulphur upon atanned hide.

Fibe-Ship, in the navy, a vessel charged with artificial fire-works, which having the wind of an enemy’s ship, grapples her,anil sets her on fire.

Fire-Stone. See Pyrites,

Fire-Works , preparations made of gun-powder, sulphur, andother inflammable and combustible ingredients, used on occasionof public rejoicings and other solemnities. The invention of fire-works is by M. Malm del attributed to the Florentines and peopleof Sienna ; who found out likewise the method of adding decora-tions to them of statues, with fire issuing from their eyes andmouths. Tb* art of preparing and managing these is called py-rofeclmy. See Pyrotechny .

FIRING, in the military art, denotes the discharge of the fire-arms; and its object is to do the utmost execution to the enemy.

The present method of firing by platoons is said to have beeninvented by Gustavus Adolphus, and first used about 11318 : thereason for this liiclhod is, that a constant fire may he alw ays keptup. There are three different ways of platoon tiring : viz. stand-ing, advancing, and retreating. Rut previous to every kind offiring, each regiment or battalion must be told off in grand divi-sions, subdivisions, and platoons, exclusively of the grenadiers,which form two subdivisions or (our platoons of themselves. Infiring standing, either by divisions or platoons, the 1st fire is fromthe division or platoon on the right; the 2d fire from the left ;the 3d from the right again ; and so on alternately, till the firingcomes to the centre platoon, which is generally called the colourplatoon, and does not fire, remaining as a reserve for the colours.Firing advancing is performed in the same manner, v ith this addi-tion, that before either division or platoon fires, it advances threepaces forward. Firing retreating varies from either of the formermethods; for before either division or platoon tires, if they aremarching from the enemy, it must go to tne right about, and afterfiring, to the left about again, and continue the retreat as slow andorderly as possible. In hedge-firing the men are drawn up twodeep, and in that order both ranks are to fire standing. Obliquefiring is cither to the right and left, or from the right and left to thecentre, according to the situation of the object. The Prussians have a particular contrivance for this purpose ; if they are to levelto the right, the rear ranks of every platoon make two quick butsmall paces to the left, and the body of each soldier turns one-eighth of a circle, and vice versa. Parapet firing depends on thenature of the parapet over which the men are to lire, and alsoupon that of the attack made to possess it. This method of firingis sometimes performed by single ranks stepping oil the banquetteand firing : each man instantly handing his arms to the centre rankot the same file, and taking his back in the room of it ; and thecentre rank giving it to the rear to load, and forwarding the armsof the rear to the front rank ; by which means the front rank mencan fire sLx or seven rounds in a minute with exactness. Parapetfiring may also be executed two deep, when the banquette isthree feet broad, or in field works, where no banquettes are made.Square firing is performed by a regiment or body of men drawnup in a hollow square, in winch case each front is generally di-vided into four divisions or firings, and the Hanks of the squarebeing the weakest part, are covered by four platoons of grena-diers. The first tire is from the right division of each face ; the2d from the left division of each face, &c. and the grenadiersmake the last fire. Street-firing is practised in two ways; eitherby making the division or platoon that has fired to wheel by halfrank to the right and left outwards from the centre, and to inarchin that order by half divisions down the flanks on each side of thecolumn, and to draw up in the rear, and go on with their primingand loading; or, to make the division or platoon, after tiring, toface to the right and left outwards from the centre, and one halfrank to follow the other; and in that order to march in one centrefile down on each side of the column into the rear, and theredraw up as before.

Firing, in farriery. See Farriery .

Firing Iron, an instrument used by farriars, resembling theblade of a knife, which being nude red-hot is applied to a horse’sskin, to discuss tumours, knots, &c. The practice is justly con-demned bv Osmer. See Farriery .

FIRKIN, an English measure of capacity for things liquid,being the fourth part of the barrel ; it contains eight gallons ofale, soap, or herrings; and nine gallons of beer.

FIRLOT, a dry measure used in Scotland . The oat firlot con-tains 21 ]jth pints of that country ; the wheat firlot contains about2,211 cubical inches; and the barley firlot, 31 standard pints.Ilence it appears that the Scotch wheal firlot exceeds the English bushel by thirty-three cubical inches.

FIRMAMENT, in the ancient astronomy, the eighth heavenor sphere; being that wherein the fixed stars were supposed to beplaced. It is called the eighth, with respect to the seven heavensor spheres of the planets which it surrounds, it was supposed tohave two motions; a diurnal motion, given it by the primummobile, from F. to W. about the poles of the ecliptic ; and ano-ther opposite motion from W. to E. ; which last it finishes, ac-cording to Tycho, in 25,412 years; according to Ptolemy , it/3ti,t)00 ; and according to Copernicus , in 258,000; in which lime