FIRE

, is that subtile invisible cause by which bodies are made hot to the touch, and expauded or enlarged in bulk; by which fluids are rarefied into vapour; or solid bodies become fluid, and at last either dissipated and carried off in vapour, or else melted into glass. It seems also to be the chief agent in nature on which animal and vegetable life have an immediate dependence.

The disputes concerning fire, which long existed among philosophers, have now in a great measure subsided. Those celebrated philosophers of the last century, Bacon, Boyle, and Newton, were of opinion, that Fire was not a substance distinct from other bodies, but that it entirely consisted in the violent motion of the parts of any body, which was produced by the mechanical force of impulsion, or of attrition. So Boyle says, when a piece of iron becomes hot by hammering, “there is nothing to make it so, except the forcible motion of the hammer impressing a vehement and variously determined agitation on the small parts of the iron.” And Bacon defines heat, which he makes synonymous with Fire, an “expansive undulatory motion in the minute particles of a body, whereby they tend with some rapidity from a centre towards a circumference, and at the same time a little upwards.” And according to Newton, Fire is a body heated so hot as to emit light copiously; for what else, says he, is red-hot iron, but Fire? and what else is a fiery coal than redhod wood? by which he suggests, that bodies which are not Fire, may be changed and converted into it.

On the other hand, the chemists strenuously contended that Fire was a fluid of a certain kind, distinct from all others, and universally present throughout the whole globe. Boerhaave particularly maintained this doctrine; and in support of it brought this argument, that flint and steel would strike fire, and produce the same degree of heat in Nova Zembla as they would do under the equator. Other arguments were drawn from the increased weight of metallic calces, which they thought proceeded from the fixing of the element of Fire in the substance whose weight was thus increased. For a long time however, the matter was most violently disputed; but the mechanical philosophers at last prevailed through the deference paid to the principles of Newton, though he himself had scarcely taken any active part in the contest.

The experiments of Dr. Black however seemed to bring the dispute to a decision, and that in favour of the chemists, concerning what he called latent-heat. From these discoveries it appears, that Fire may exist in bodies in such a manner, as not to discover itself in any other way than by its action on the minute parts of the body; but that suddenly this action may be changed in such a manner, as no longer to be directed upon the particles of the body itself, but upon external objects; in which case we then perceive its action by our sense of | feeling, or discover it by the thermometer, and call it heat, or sensible Fire.

From this discovery, and others in electricity, it is now pretty generally allowed, that Fire is a distinct fluid, capable of being transferred from one body to another. But when this was discovered, another question no less perplexing arose, viz, what kind of a fluid it was; or whether it bears any analogy to those with which we are better acquainted. Now there are found two fluids, viz, the solar light, and the electric matter, both of which occasionally act as fire, and which therefore seem likely to be all the same at the bottom; and popularly the matter has been long since determined; the solar rays and the electric fluid having been indifferently accounted elementary Fire. Some indeed have imagined both these fluids to be mere phlogiston itself, or at least containing a large portion of it; and Mr. Scheele went so far in this way as to form an hypothesis, which he endeavoured to support by experiments, that Fire is composed of phlogiston and dephlogisticated air. But it is now ascertained beyond doubt, that the result of such a combination is not Fire, but sixed air.

It was long since observed by Newton, that heat was certainly conveyed by a medium more subtile than the common air; for two thermometers, one included in the vacuum of an air-pump, the other placed in the open air, at an equal distance from the fire, would grow equally hot in nearly the same time. This and other experiments shew, that Fire exists and acts where there is no other matter, and of consequence it is a fluid per se, independent of every terrestrial substance, without being generated or compounded of any thing we are yet acquainted with. To determine the nature of the fluid, we have only to consider whether any other can be discovered which will pass through the perfect vacuum just mentioned, and act there as Fire. Such a fluid is found in the solar light, which is well known to act even in vacuo as the most violent Fire. The solar light will likewise act in the very same manner in the most intense cold; for M. de Saussure has found, that on the cold mountain top the sun-beams are equally powerful as on the plain below, if not more so. It appears therefore, that the solar light will produce heat independent of any other substance whatever; that is, where no other body is present, at least as far as we can judge, except the light itself, and the body to be acted upon. We cannot therefore avoid concluding, that a certain modification of the solar light is the cause of heat, expansion, vapour, &c, and answers to the rest of the characters given in the foregoing definition of Fire, and that independent of any other substance whatever.

It is very probable too, that the electric matter is no other than the solar light absorbed by the earth, and thus becoming subject to new laws, and assuming many properties apparently different from what it has when it acts as light. Even in this case it manifests its identity with Fire or light, viz, by producing a most intense heat where a large quantity of it passes through a small space. So that at any rate, the experiments which have already been made, and the proofs drawn from the phenomena of nature, shew such a strong affinity between the elements of Fire, light and electricity, that we may not only assert their identity upon the most probable grounds, but lay it down as a position against which at present no argument of any weight has an existence.

Fire-Arrow, is a small iron dart, furnished with springs and bars, and also a match impregnated with sulphur and powder, which is wound about its shaft. It is chiefly used by privateers and pirates to fire the sails of the enemy's ship, and for this purpose it is discharged from a musketoon, or a swivel gun. The match being kindled by the explosion, it communicates the flame to the sail against which it is directed, where the arrow fastens itself by means of its bars and springs. This weapon is peculiar to hot climates, particularly the West Indies; the sails being very dry, are quickly set on Fire, and the Fire is soon conveyed to the masts, rigging, and finally to the vessel itself.

Fire-Balls, in Artillery, are certain balls composed of combustible matters, such as fine or mealed powder, sulphur, saltpetre, rosin, pitch, &c. These are thrown into the enemy's works in the night time, to discover where they are; or to set Fire to houses, galleries, or blinds of the besiegers, &c. They are sometimes armed with spikes or hooks of iron, that they may not roll off, but stick or hang where they are to take effect.

Fire-Balls, or Fiery-Meteors, in Meteorology, a kind of luminous bodies usually appearing at a great height above the earth, with a splendor surpassing that of the moon, and sometimes apparently as large. They have not been found to observe any regular course or motion, but, on the contrary, moving in all directions, and with very different degrees of celerity; frequently breaking into several smaller ones; sometimes making a strong hissing sound, sometimes bursting or vanishing with a loud report, and sometimes not.

These luminous appearances doubtless constitute one part of the ancient prodigies, blazing stars, or comets, which last they sometimes resemble in being attended with a train; but more often they appear round. The first of these of which we have any accurate account, was observed by Dr. Halley, and some other philosophers at different places, in the year 1719, the height of which above the surface of the earth was computed at more than 70 miles. Many others have been pretty accurately observed since that time, and described by philosophers, as in the French Memoirs, and in the Philos. Trans. vols. 30, 41, 42, 43, 46, 47, 48, 51, 53, 54, 63, 74, &c. The velocities, directions, appearances, and heights of all these were found to be very various; though the height of all of them was supposed above the limits assigned to our atmosphere, or where it loses its refractive power. The most remarkable of those on record, appeared on the 18th of August 1783, about 9 o'clock in the evening. It was seen to the northward of Shetland, and took a southcasterly direction for an immense space, being observed as far as the southern provinces of France, and by some it was said to have been seen at Rome, passing over a space of 1000 miles in about half a minute of time, and at a very great height. During its course it appeared several times to change its shape; sometimes appearing in the form of one ball, sometimes of two or more; sometimes with a train, and sometimes without one.

There are divers opinions concerning the nature and | origin of these Fire-balls. The first thing that occurred to philosophers on this subject was, that the meteors in question were burning bodies rising from the surface of the earth, and flying through the atmosphere with great rapidity. But this hypothesis was soon rejected, on considering that there was no power known by which such bodies could either be raised to a sufficient height, or projected with the velocity of the meteors. The next hypothesis was, that, instead of one single body, they consist of a train of sulphureous vapours, extending a vast way through the atmosphere, and being kindled at one end, display the luminous appearances in question by the fire running from one end of the train to the other. But it is not easy to conceive how such matters can exist and be disposed in such lines in so rare a part of the atmosphere, and even to burn there, in an almost perfect vacuum. For which reason this hypothesis was abandoned, for another, which was, that those meteors are permanent solid bodies, not rising from the earth, but revolving round it in very excentric orbits, and thus in their perigeon moving with vast rapidity. But as the various appearances of one and the same meteor, to observers at different places, are not compatible with the idea of a single body so revolving, this hypothesis has also been given up in its turn. Another hypothesis that has sometimes been advanced is this; viz, that these meteors are a kind of bodies that take fire as soon as they come within the atmosphere of the earth. But this cannot be supposed without implying a previous knowledge of these bodies, which it is impossible we can have. The only opportunity we can have of seeing them, is when they are on fire. Before that time they are in an invisible and unknown state; and it is surely improper to argue concerning them in this state, or pretend to determine any one of their properties, when it is not in our power at all to see or investigate them. As these meteors therefore never manifest themselves to our senses but when they are on fire, the only rational conclusion we can draw from thence is, that they have no existence in any other state; and consequently that their substance must be composed of that fluid which, when acting after a certain manner, becomes luminous and shews itself as fire; remaining invisible and eluding our researches in every other case. On this hypothesis, it is now pretty generally concluded, that the Fire-balls are great bodies of electric matter, moving from one part of the heavens where, to our conception, it is superabundant, to another where it is desicient: a conclusion attended with much probability, from the analogy observed between electricity and the phenomena of these meteors: and hence these Fireballs appear to be of the same family with shootingstars, lightning, the aurora-borealis, &c, being all referred to the same origin, viz, the electricity of the atmosphere.

Fire-Engine, is a machine for extinguishing accidental Fires by means of a stream or jet of water. The common squirting Fire-engine consists of a lifting pump placed in a vessel of water, and wrought by two levers that act always together. During the stroke, the water raised by the piston of the pump spouts forcibly through a pipe joined to the pump-barrel, and made capable of any degree of elevation by means of a yield- ing leather pipe, or by a ball and socket turning every way, screwed on the top of the pump. The vessel containing the water is covered with a strainer, to prevent the mud, &c, which is poured into it with the water, from choking the pump-work. Between the strokes of this engine the stream is discontinued, for want of an air vessel. However, in some cases, Engines of this construction have their use, because the stream, though interrupted, is much smarter than when the engine is made to throw water in a continued stream. See these Engines particularly described in Desaguliers's Exper. Philos. vol. 2, pa. 505; or Martin's Philos. Britan. vol. 2, pa. 69. See also the figure of them, plate viii. fig. 3.

Fire-Engine, is also sometimes used for the machine employed in raising water by steam, and more properly called Steam-Engine; which see.

Fire-Lock, or Fusil, a small gun or musket, which fires with a flint and steel; as distinguished from the old musket, or match-lock, which was fired with a match. The Fire-lock is now in common use with the European armies, and carried by the foot-soldiers. It is usually about 3 feet 8 inches in the barrel; and, including the stock, 4 feet 8 inches, carrying a leaden bullet, of which 29 make 2lb. The diameter of the ball is .55, and that of the barrel .56 parts of an inch. The time of the invention of Fire-locks is uncertain; but they were used in 1690.

Fire-Places, are contrivances for communicating heat to rooms, and also for answering various purposes of art and manufacture.

The general properties of air and fire, on which their construction chiefly depends, are the following, viz, that air is rarefied by heat, and condensed by cold; i. e. the same quantity of air takes up more space when warm than when cold. Air rarefied and expanded by heat, is specifically lighter than it was before, and will rise in other air of greater density: so that a sire being made in any chimney, the air about and over the fire is rarefied by the heat, thence becomes lighter, and so rises in the funnel, and goes out at the top of the chimney: the other air in the room, flowing towards the chimney, supplies its place, is then rarefied in its turn, and rises likewise; and the place of the air thus carried out of the room, is supplied by fresh air coming in through doors and windows, or, if they be shut, through every crevice with violence; or if the avenues to the room be so closed up, that little or no fresh supply of air can be obtained, the current up the funnel must flag; and the smoke, no longer driven up, float about in the room.

Upon these principles, various contrivances and kinds of Fire-grates and stoves have been devised, from the old very open and wide chimney places, down to the present modish ones, which are much narrowed in the front, opening, by side and back jambs, and a low breast or mantle, besides the convenience of a flap, called a register, that covers the top of the Fire-stove, but opening to any degree with a small winch, which lifts the back part sloping upwards, and so throws the smoke freely up the funnel, and yet admitting as little air to pass as you please; by which simple means the warm air is kept very much in the room, while the very narrow and sloping orifice promotes the brisk ascent of | the smoke, and yet prevents its return down again, for the same reason.

Another very ingenious, but more complex, apparatus, called the Pensylvania Fire-place, was invented by Dr. Franklin, by which a room is kept very warm by a constant supply of fresh hot air, that passes into it through the stove itself. See the description in his Letters and Papers on Philosophical Subjects.

Fire-Pot, in the Military Art, is a small earthen pot, into which is put a grenade, filled with fine powder till the grenade be covered; the pot is then covered with a piece of parchment, and two pieces of match laid across and lighted. This pot being thrown where it is designed to do execution, breaks and fires the powder, and this again fires the powder in the grenade, which ought to have no fuze, that its operation may be the quicker.

Rasant, or Razant Fire, is a fire from the artillery and small arms, directed parallel to the horizon, or to those parts of the works of a place that are defended.

Running Fire, is when ranks of men fire one after another; or when the lines of an army are drawn out to fire on account of a victory; in which case each squadron or battalion takes the fire from that on its right, from the right of the first line to the left, and from the lest to the right of the second line, &c.

Fire-Ships, in the Navy, are vessels charged with combustible materials or artificial Fire-works; which having the wind of an enemy's ship, grapple her, and set her on fire.

Anderson, in his History of Commerce, vol. 1, pa. 432, ascribes the invention to the English, in this instance, viz, some vessels being filled with combustible matter, and sent among the Spanish ships composing the Invincible Armada in 1588; and hence arose it is said the terrible invention of Fire-ships.

But Livy informs us, that the Rhodians had invented a kind of Fire-ships, which were used in junction with the Roman fleet in their engagement with the Syrians, in the year 190 before Christ: cauldrons of combustible and burning materials were hung out at their prows, so that none of the enemies' ships durst approach them: for these fell on the enemies' gallies, struck their beaks into them, and at the same time set them on fire. Livy, lib. 37, cap. 30.

Wild-Fire, is a kind of artificial or factitious fire, that burns even under water, and that with greater violence than out of it. It is composed of sulphur, naphtha, pitch, gum, and bitumen, and it is only extinguishable by vinegar, mixed with sand and urine, or by covering it with raw hides. It is said its motion is contrary to that of natural fire, always following the direction in which it is thrown, whether it be downwards, sideways, or otherwise.

The French call it Greek Fire, or Feu Gregeois, because first used by the Greeks about the year 660, as is observed by the Jesuit Petavius, on the authority of Nicetas, Theophanes, Cedrenus, &c. The inventor, according to the same author, was an engineer of Heliopolis, in Syria, named Callinicus, who first applied it in the sea-fight commanded by Constantine Pogonates, against the Saracens, near Cyzicus, in the Hellespont; and with such effect, that he burnt the whole fleet, which contained 30,000 men. But others refer it to a much older date, and ascribe the invention to Marcus Gracchus; an opinion which is supported by several passages, both in the Greek and Roman writers; which shew that it was anciently used by both these nations in their wars. See Scaliger against Cardan.

The successors of Constantine used it on several occasions, with great advantage: and it is remarkable that they were able to keep the secret of the composition to themselves; so that no other nation knew it in the year 960.

It is recorded by Chorier, in his Hist. de Dauph. that Hugh, king of Burgundy, demanding ships of the emperor Leo for the siege of Fresne, desired also the Greek Fire.

And F. Daniel gives a good description of the Greek Fire, in his account of the siege of Damietta, under St. Louis. Every body, says he, was astonished with the Greek Fire, which the Turks then prepared; and the secret of which is now lost. They threw it out of a kind of mortar, and sometimes shot it with an odd sort of cross-bow, which was strongly bent by means of a handle, or winch, of much greater force than the bare arm. That which was thrown from the mortar sometimes appeared in the air of the size of a tun, with a long tail, and a noise like that of thunder. The French, by degrees, got the secret of extinguishing it; in which they succeeded several times.

After all, perhaps the invention of the Wild-Fire is to be ascribed to other nations, and to a still older date, and that it was the same as that used among the Indians in Alexander's invasion, when it was said they fought with thunder and lightning, or shot Fire with a terrible noise.

Fire-Works, otherwise called Pyrotechnia, are artificial Fires, or preparations made of gunpowder, sulphur, and other inflammable and combustible ingredients, used on occasion of public rejoicings, and other solemnities. The principal of these are rockets, serpents, stars, hail, mines, bombs, garlands, letters, and other devices.

The invention of Fire-works is attributed, by M. Mahudel, to the Florentines and people of Sienna; who found out likewise the method of adding to them decorations of statues, with fire issuing from their eyes and mouths.

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Entry taken from A Mathematical and Philosophical Dictionary, by Charles Hutton, 1796.

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FIGURAL
FIGURE
FILLET
FINITE
FINITOR
* FIRE
FIRKIN
FIRLOT
FIRMAMENT
FIRMNESS
FISSURES