in physiology, signifies that subtile invisible cause by which bodies are expanded or enlarged in bulk, and become hot to the touch; fluids are rarefied into vapour; solid bodies become fluid, and in like manner are at last dissipated, or if incapable of being carried off in vapour are at length melted into glass. It seems likewise to be the chief agent in nature on which animal and vegetable life have an immediate dependence, and without which it does not appear that nature itself could subsist a single moment.

The disputes concerning fire, which for a long time divided philosophers, have now in a great measure, though not wholly, subsided. The celebrated philosophers of the last century, Bacon, Boyle, and Newton, were of opinion, that fire was no distinct substance from other bodies, but that it consisted entirely in the violent motion of the parts of any body. As no motion, however, can be produced without a cause, they were obliged to have recourse to a mechanical force or impulse as the ultimate cause of fire in all cases. Thus Boyle tells us, that 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." Bacon defines heat, which he makes synonymous with fire, to be "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." Sir Isaac Newton said nothing positive upon the subject; but conjectured that grofs bodies and light might be convertible into one another; and that great bodies of the size of our earth when violently heated, might continue and increase their heat by the mutual action and reaction of their parts.

But while the mechanical philosophers thus endeavoured to account for the phenomena of fire upon the same principles which they judged sufficient to explain those of the universe in general, the chemists as strenuously asserted 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 the following argument, that steel and flint would strike fire, and produce the very same degree of heat in Nova Zembla which they would do under the equator. Other arguments were drawn from the increased weight of metallic calces, which they supposed to proceed from the fixing of the element of fire in the substance whose weight was thus increased. By these experiments Mr Boyle himself seems to have been staggered; as he published a treatise on the possibility of making fire and flame ponderable; though this was directly contrary to his own principles already quoted. For a long time, however, the matter was most violently disputed; and the mechanical philosophers, though their arguments were equally inconclusive with those of their adversaries, at last prevailed through the prejudice in favour of Sir Isaac Newton, who indeed had scarce taken any active part in the contest.

That the cause of fire cannot be any mechanical motion which we can impress, is very evident; because on mechanical principles an effect must always be proportionable to the cause. In the case of fire, however, the effect is beyond all calculation greater than the cause, supposing the latter to be only a mechanical percussion, as in the case of hammering iron till it be red hot. By a few strokes of an hammer, the particles of a piece of iron, we shall allow, may be set in a violent motion, and thus produce fire. If, however, we direct the motion of these particles upon another body whose parts are at rest, and in some degree coherent, it is plain that the latter will resist and diminish the motion of the particles already moved, in proportion to their vis inertiae, as well as the cohesion of the parts of the second body, if indeed we can suppose the vis inertiae of matter to be different from the effect of gravitation, cohesion, or some other power acting upon it. By no argumentation whatever, then, can we show upon mechanical principles, why fire should have such a tendency to increase and multiply itself without end, as we see it has, even abstracting from all consideration of the necessity of air for continuing the action of fire. The action of the air in augmenting and continuing the power of fire, seems scarce at all to have been considered by those who first undertook an investigation of the subject. It evidently gave rise to the Hutchinsonian hypothesis, that fire, light, and air, were convertible into one another. This, however, is equally untenable with the mechanical hypothesis: for later discoveries have shown, that our atmosphere is composed of two distinct fluids, only one of which is fit for supporting flame; and if we should suppose this to be the only proper air, it is in like manner demonstrated, that this pure fluid is not homogeneous, but composed of a gravitating and non-gravitating substance; the latter of which only has the properties of fire: so that this element is still as invisible as ever; nor can it be shown by any experiment that fire per se has ever been changed into a palpable or gravitating substance.

The experiments which first seemed to bring this dispute to a decision were those of Dr Black, concerning what he called latent heat; on which some other names, such as absolute heat, specific fire, &c., have been bestowed, very little to the advancement of science in general. 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 upon 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 sensible heat. This expression, it must be owned, is improper; and the use of the word heat, instead of fire, has produced some confusion, which it is not now easy to avoid in speaking on these subjects. By the word heat, we ought always to understand the effect of fire, or the fluid acting in a certain manner, rather than the mere element itself; which, it is certain, from the experiments just mentioned, may exist in substances actually cold to the touch.

From this discovery made by Dr Black, along with many others in electricity, and recorded at length in various articles of this work, it is now almost universally 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 occurred, viz. what kind of a fluid it was; or whether it bears any analogy to those with which we are better acquainted? Here we find 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 bottom. By the vulgar, indeed, the matter has long ago been determined; and the rays of the sun as well as the electrical fluid have been promiscuously denominated elementary fire. Philosophers, indeed, have withheld their assent; though their reasons for so doing are by no means apparent. The most strange suppositions, however, have been made concerning the nature of both those fluids, and on the most slender grounds imaginable; or rather, on no grounds at all, they have been supposed to be phlogiston itself, or to contain a large proportion of it. Mr Scheele went so far in this way as to form an hypothesis, which he endeavoured to support by some experiments, that fire is composed of dephlogisticated air and phlogiston. But it is now ascertained beyond all possibility of dispute, that the result of such a combination is not fire, but fixed air: so that we need not take any farther notice of this hypothesis than just to observe, that it would have been altogether untenable, even though this discovery had not been made; because the dephlogisticated air itself is not a simple but a compound substance, as has already been observed; and that in all cases of combustion the one part of the air is separated from the other.

It was long ago observed by Sir Isaac Newton, that heat was certainly conveyed by a medium more subtle than the common air; because 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. The consequence of this, had he pursued the thought, was, that fire itself was equally present in all places, and as active where there was no terrestrial matter as where there was. New improvements in the air-pump have enabled succeeding philosophers to make more perfect vacuums, such as it has been supposed even the electric matter cannot pass through. It is not to be doubted, however, that, even there, the thermometer would be heated by a fire as well as in the open air. Fire, therefore, exists and acts where there is no other matter, and of consequence 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 we find 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, nay more powerful, than on the plain below. 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 light of the sun is the cause which produces heat, expansion, vapour, &c., and answers to the rest of the characters given in our definition of fire, and that independent of any other substance whatever.

Under the article Electricity, Sect. vi. we have endeavoured to show that the electric matter is no other than the light of the sun absorbed by the earth, and thus becoming subject to new laws, and affuming 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. In vacuo, indeed, we cannot manage it in such a manner as to make the proof decisive. But though this must be accounted a defect, it never can amount to any positive proof that electricity and fire are different. We see that in some cases they produce the very same effects; and if they do not so in all, we ought rather to account for the difference from the variation of circumstances, and our want of knowledge or abilities. ties to make proper experiments, than to multiply elements without any necessity, when one is evidently capable of answering all the purposes of nature. At any rate, the experiments which have already been made, and the proofs adduced from the phenomena of nature, show such a strong affinity between the elements of fire, light, and electricity, that we may not only affect their identity upon the most probable grounds, but lay it down as a position against which no argument of any weight has an existence at present. For a further discussion of this subject, see Chemistry, Part I. Sect. i. Electricity, Sect. vi. Heat, Flame, Fluidity, &c.

Wild Fire, a kind of artificial or fictitious fire, which burns even under water, and that with greater violence than out of it.

It is composed of sulphur, naphtha, pitch, gum, and bitumen; and is only extinguishable by vinegar mixed with sand and urine, or by raw hides.

Its motion or tendency is said to be contrary to that of natural fire, and always follows the direction in which it is thrown; whether it be downwards, sidewise, or otherwise. The French call it Greek fire, or fu Gregorius, 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 Jesuit, was an engineer of Heliopolis, in Syria, named Gallinicus, 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 therewith, wherein were 30,000 men. But others will have it of a much older date; and hold Marcus Gracchus the inventor: which opinion is supported by several passages both in the Greek and Roman writers, which shows it to have been anciently used by both these nations in their wars.

Constantine's successors used it on divers occasions with equal advantage as himself; and what is remarkable enough is, that they were so happy as to keep the secret of the composition to themselves, so that no other nation knew it in the year 960.

Hugh king of Burgundy, demanding ships of the emperor Leo, for the siege of Fresne, desired likewise the Greek fire.

F. Daniel gives us a good description of the Greek fire in his account of the siege of Damietta under St Louis. Every body, says that author, was affrighted with the Greek fire, which the Turks then prepared; and the secret whereof 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 mere arm. That thrown with 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.

Machine for Preserving from Fires. This machine consists of a pole, a rope, and a basket. The pole is of fir, or a common scaffold pole, of any convenient length from 36 to 46 feet; the diameter at bottom, or greatest end, about five inches; and at the top, or smallest end, about three inches. At three feet from the top is a mortise through the pole, and a pulley fixed to it of nearly the same diameter with the pole in that part. The rope is about three quarters of an inch diameter, and twice the length of the pole, with a spring hook at one end, to pass through the ring in the handle of the basket when used: it is put through the mortise over the pulley, and then drawn tight on each side to near the bottom of the pole, and made fast there till wanted. The basket should be of strong wicker-work, three feet and a half long, two feet and a half wide, rounded off at the corners, and four feet deep, rounding every way at the bottom. To the top of the basket is fixed a strong iron curve or handle, with an eye or ring in the middle; and to one side of the basket, near the top, is fixed a small cord, or guide-rope, of about the length of the pole. When the pole is raised, and set against a house over the window from which any persons are to escape, the manner of using it is so plain and obvious, that it needs not be described. The most convenient distance from the house for the foot of the pole to stand, where practicable, is about 12 or 14 feet. If two strong iron straps, about three feet long, riveted to a bar cross, and spreading about 14 inches at the foot, were fixed at the bottom of the pole, this would prevent its turning round or slipping on the pavement. And if a strong iron hoop, or ferule, rivetted (or welded) to a semicircular piece of iron spreading about 12 inches, and pointed at the ends, were fixed on at the top of the pole, it would prevent its sliding against the wall.

When these two last mentioned irons are fixed on, they give the pole all the steadiness of a ladder; and because it is not easy, except to persons who have been used to it, to raise and set upright a pole of 40 feet or more in length, it will be convenient to have two small poles or spars of about two inches diameter, fixed to the sides of the great pole at about two or three feet above the middle of it, by iron eyes riveted to two plates, so as to turn every way; the lower end of these spars to reach within a foot of the bottom of the great pole, and to have ferules and short spikes to prevent sliding on the pavement, when used occasionally to support the great pole like a tripod. There should be two strong ash trundles let through the pole, one at four feet and one at five feet from the bottom, to stand out about eight inches on each side, and to serve as handles, or to twist the rope round in lowering a very heavy weight. If a block and pulley were fixed at about the middle of the rope, above the other pulley, and the other part of the rope made to run double, it would diminish any weight in the basket nearly one-half, and be very useful in drawing any person up, to the assistance of those in the chambers, or for removing any effects out of a chamber, which it might be dangerous to attempt by the stairs.

It has been proved, by repeated trials, that such a pole as we have been speaking of can be raised from the ground, and two or three persons taken out of the upper windows of an house, and set down safely in the street, in the space of 35 seconds, or a little more than half a minute. Sick and infirm persons, women, children, and many others, who cannot make use of a ladder, may be safely and easily brought down from any of the windows of an house on fire by this machine, and, by putting a short pole through the handles of the basket, may be removed to any distance without being taken out of the basket. The pole must always have the rope ready fixed to it, and may be conveniently laid up upon two or three iron hooks under any shade or gate-way, and the basket should be kept at the watch-house. When the pole is laid up, the two spars should always be turned towards the head of it. The basket should be made of peeled rods, and the pole and spars painted of a light stone-colour, to render it more visible when used in the night.

Machines for extinguishing Fire. In the year 1734, the state of Sweden offered a premium of 20,000 crowns for the best method of stopping the progress of accidental fires; when one Mr Fuches, a German physician, made a preparation for that end, and the experiment was made on a house built on purpose, of dry fir, at Legard island. In the building were placed several tubs of tar and pitch, and a great quantity of chips, all which were set on fire; flames issuing through the top of the house, windows, &c., when he threw in one of the barrels containing the preparation, which immediately quenched the flames; a second barrel entirely cleared the smoke away; and the whole was executed to the satisfaction of the spectators, and to the no small satisfaction of the inventor, who was about to return home, when unexpectedly the flames broke out again, supposed to be occasioned by a small quantity of combustible matter being introduced and set on fire secretly by some malicious person. Upon this the wrong-headed mob fell upon Mr Fuches, and beat him most unmercifully, so that he narrowly escaped with his life. He soon after left the country, and never could be prevailed on (though strongly persuaded by some of the most eminent citizens) to return. It is said, another experiment of the same kind was tried in the year 1761 in Holland; but rendered abortive through the perversion of the populace.

Attempts of a similar nature have met with a better reception in England. Of these the most successful was that of Mr Godfrey, whose contrivance is thus described by Mr Ambrose Godfrey, grandson to the inventor. "The machine to be employed consists of a small portion of gunpowder closely confined; which, when animated by fire, acts by its elastic force upon a proper medium, and not only divideth it into the minutest atoms, but disperseth it also in every direction, so as immediately to extinguish any fire within a certain distance. This medium is a liquor strongly impregnated with a preparation of antiphlogistic principles, which by their action upon burning materials extinguish the flames, and reduce them in general to the state of a black coal; and, by its opposite nature to fire, hinders the remaining sparks, notwithstanding the admission of the air, from kindling the flames afresh. By this means, the great point is obtained, in giving sufficient time for totally extinguishing any remains of fire.

"They who presume that water only will perform this will find themselves greatly mistaken, as the draught of air will certainly rekindle the neighbouring materials, which are very fit to receive a fresh flame; the fire not being extinguished by the quantity of water, but rather by the expansion and rarefaction of its particles. There are several sizes of these machines, from five to fifty pounds weight, in a portable and rather small compass, and may generally be carried to any place where a man can go himself.

"But though these machines will prevent great fires by a timely application, they will not extinguish them after they have reached a frightful height, and several houses, perhaps near a whole street, are in flames. The floors must be standing, and access to the building safe, otherwise no person can be supposed to approach near enough to apply them in a proper manner. Every fire has its beginning for the most part in some apartment; and, as soon as discovered, the family, instead of losing all presence of mind, should immediately apply one or more of these machines, which will then fully answer the intention. The proper time of applying them, supposes that they are ready at hand. It will be in vain to think of fetching them from any considerable distance, as it will then be too late for them to perform any important service; except indeed being the probable means of saving some adjacent house, by extinguishing the flames as often as they break out, till the building first on fire is totally consumed, and, by falling into ruins, leaves the other in perfect safety."

On the 19th of May 1761, at noon, Mr Godfrey's experiment for extinguishing fire, was tried in an house erected for that purpose, near Mary-le-bone. Their royal highnesses the duke of York, prince William Henry, prince Henry Frederic, a great number of persons of rank and distinction, and many of the learned world, gave their attendance on this singular occasion. The house, which is of brick, consists of three rooms one above another, a stair-case, chimney, lath-and-plaster ceilings, and a kind of wainscoting round the rooms, of rough deal. Exactly at 12 o'clock the ground room, and that up one pair of stairs, were set on fire, by lighting the faggots and shavings laid in there for that purpose: in about 15 minutes the wainscot of the under room was thought to be sufficiently in flames, and three of the machines were thrown in; which, by almost immediate and sudden explosions, instantaneously extinguished the flames, and the very smoke in that apartment in a few minutes totally disappeared. By this time, the firemen, &c., who had the care of throwing in the machines, gave an alarm that the stair case had taken fire, and that it was necessary directly to go to work upon the next room; which was accordingly done, and with the same effect. The experiment, however, hitherto did not universally satisfy: in the last instance especially it was thought to be too hastily put in execution; and the populace without-side the paling, who were supposed to amount to near 20,000, and whose curiosity, from the very nature of their situation, remained much dissatisfied, began to grow rather riotous, and talked of a second bottle-conjuror. For the sake of the experiment, therefore, and to remove all manner of doubt, Mr Godfrey consented to a third experiment in the upper room, which was entirely of wood. The flames were now suffered to get to a considerable height, and even the window frames destroyed, before the machines were thrown in; which, however, answered exactly as the former had done; and, being quite in sight of the out-standers, met with universal approbation.

These machines of Mr Godfrey's, it is evident, would be of great use in extinguishing fires on shipboard; and might be considered as a no less necessary part of a ship's lading, than her stores or ammunition.

The hint of these machines is said to have been taken by Dr Godfrey from the invention of one Zachary Grey, Greyt, who exhibited machines similar to those of Dr Godfrey, before persons of the first rank, but without meeting with any encouragement. His machines were made of wood, and the liquor employed was only water, and consequently inferior to Dr Godfrey's in its power of extinguishing fire. The latter is said to have mixed his water with a certain quantity of oil of vitriol, or with sal ammoniac. These machines, however, as already observed, are found to be only serviceable in the beginning of a fire. When the roof had fallen in, they had no effect.

Water-Engine for Extinguishing Fire. See Hydrostatics, no. 33.

In using this machine we have the following improvement by Dr Hoffman, which promises to be of great efficacy. As soon as the engine is in readiness to work, fill into the water that immediately is to be discharged, seven or eight pounds of pearl-ashes in powder, and continue to add it in this manner as occasion requires; taking care that it be directed against the timber or wainscot, &c., just beginning to burn, and not walled against the brickwork; or, where time will admit, dissolve any quantity of pearl-ashes in a copper with water, and as fast as it dissolves, which will be in a few minutes, mix a pail full with the water in the engine, pretty often; and whatever burning wood it is played upon, will be extinguished as if it was dipped in water, and will not burn afresh in the part extinguished.

Easy Method of Extinguishing Fire in Chimneys. It is well known, that the inner parts of chimneys easily take fire; the foot that kindles therein emits a greater flame, according as the tunnel is more elevated, because the inferior air feeds the fire. If this air could therefore be suppressed, the fire would soon be extinguished. In order to this, some discharge a pistol into the chimney, which produces no effect; others lay under the chimney a copper full of water; but the vapours that rise from it, far from extinguishing the fire, seem to give it new force. Water thrown into the chimney at top is equally of no effect, because it comes down through the middle of the tunnel, and not along the sides. It would be more advisable to stop with dung the upper orifices of the tunnel for quenching the fire. But the surest and readiest method is, to take a little gunpowder, and having humected it with spittle for binding it, to form it into small masses, and to throw it into the heart of the chimney. When it is burnt, and has produced a considerable vapour, a second, afterwards a third, are thrown, and so on, as much as is necessary. In a little time the fire is extinguished, and, as it were, choked by this vapour; and cakes of inflamed foot are seen to fall from the tunnel, till at last not the least vestige of fire appears.

Securing Buildings against Fire. Dr Hales proposes to check the progress of fires by covering the floors of the adjoining houses with earth. The proposal is founded on an experiment which he made with a fir-board half an inch thick, part of which he covered with an inch depth of damp garden mould, and then lighted a fire on the surface of the mould; though the fire was kept up by blowing, it was two hours before the board was burnt through, and the earth prevented it from flaming. The thicker the earth is laid on the floors, the better; however, Dr Hales apprehends that the depth of an inch will generally be sufficient; and he recommends to lay a deeper covering on the stairs, because the fire commonly ascends by them with the greatest velocity.

M. Hartley made several trials in the years 1775 and 1776, in order to evince the efficacy of a method which he had invented for restraining the spread of fire in buildings. For this purpose thin iron plates are well nailed to the tops of the joists, &c., the edges of the sides and ends being lapped over, folded together, and hammered close. Partitions, stairs, and floors, may be defended in the same manner; and plates applied to one side have been found sufficient. The plates are so thin as not to prevent the floor from being nailed on the joists, in the same manner as if this preventative were not used; they are kept from rust by being painted or varnished with oil and turpentine. The expense of this addition, when extending through a whole building, is estimated at about 5 per cent. Mr Hartley has a patent for this invention, and parliament has voted a sum of money towards defraying the expense of his numerous experiments. The same preservative may also be applied to ships, furniture, &c.

Lord Mahon has also discovered and published a very simple and effectual method of securing every kind of building against all danger of fire. This method he has divided into three parts, viz. under-flooring, extra-lathing, and inter-securing.

The method of underflooring is either single or double. In single underflooring, a common strong lath of oak, or fir, about one-fourth of an inch thick, should be nailed against each side of every joist, and of every main timber supporting the floor which is to be secured. Other similar laths are then to be nailed along the whole length of the joists, with their ends butting against each other. The top of each of these laths or fillets ought to be at 1½ inch below the top of the joists or timbers against which they are nailed; and they will thus form a sort of small ledge on each side of all the joists. These fillets are to be well bedded in a rough plaster hereafter mentioned, when they are nailed on, so that there may be no interval between them and the joists; and the same plaster ought to be spread with a trowel upon the tops of all the fillets, and along the sides of that part of the joists which is between the top of the fillets and the upper edge of the joists. In order to fill up the intervals between the joists that support the floor, short pieces of common laths, whose length is equal to the width of these intervals, should be laid in the contrary direction to the joists, and close together in a row, so as to touch one another; their ends must rest upon the fillets, and they ought to be well bedded in the rough plaster, but are not to be fastened with nails. They must then be covered with one thick coat of the rough plaster, which is to be spread over them to the level of the tops of the joists; and in a day or two this plaster should be trowelled over close to the sides of the joists, without covering the tops of the joists with it.

In the method of double-flooring, the fillets and short pieces of laths are applied in the manner already described; but the coat of rough plaster ought to be little more than half as thick as that in the former method. Whilst this rough plaster is laid on, some more of the short pieces of laths above mentioned must be laid in the intervals between the joists upon the first coat, coat, and be dipped deep in it. They should be laid as close as possible to each other, and in the same direction with the first layer of short laths. Over this second layer of short laths there must be spread another coat of rough plaster, which should be trowelled level with the tops of the joists without rising above them. The rough plaster may be made of coarse lime and hair; or, instead of hair, hay chopped to about three inches in length may be substituted with advantage. One measure of common rough sand, two measures of slack lime, and three measures of chopped hay, will form in general a very good proportion, when sufficiently beat up together in the manner of common mortar. The hay should be put in after the two other ingredients are well beat up together with water. This plaster should be made stiff; and when the flooring boards are required to be laid down very soon, a fourth or fifth part of quicklime in powder, formed by dropping a small quantity of water on the limestone a little while before it is used, and well mixed with this rough plaster, will cause it to dry very fast. If any cracks appear in the rough plaster-work near the joists when it is thoroughly dry, they ought to be closed by washing them over with a brush wet with mortar-wash; this wash may be prepared by putting two measures of quicklime and one of common sand in a pail, and stirring the mixture with water till the water becomes of the consistence of a thin jelly.

Before the flooring boards are laid, a small quantity of very dry common sand should be strewed over the plaster-work, and struck smooth with an hollow rule, moved in the direction of the joists, so that it may lie rounding between each pair of joists. The plaster-work and sand should be perfectly dry before the boards are laid, for fear of the dry rot. The method of under-flooring may be successfully applied to a wooden stair-case; but no sand is to be laid upon the rough plaster-work. The method of extra-lathing may be applied to ceiling joists, sloping roofs, and to wooden partitions.

The third method, which is that of inter-securings, is very similar to that of under-flooring; but no sand is afterwards to be laid upon it. Inter-securings are applicable to the same parts of a building as the method of extra-lathing, but it is seldom necessary.

Lord Mahon has made several experiments in order to demonstrate the efficacy of these methods. In most houses it is only necessary to secure the floors; and the extra-expense of under-flooring, including all materials, is only about nine pence per square yard, and with the use of quicklime a little more. The extra-expense of extra-lathing is no more than six pence per square yard for the timber side-walls and partitions; but for the ceiling about nine pence per square yard. But in most houses no extra-lathing is necessary.

Fire-Eater. We have a great number of mountebanks who have procured the attention and wonder of the public by eating fire, walking on fire, washing their hands in melted lead, and the like tricks.

The most celebrated of these was our countryman Richardson, much talked of abroad. His secret, as related in the Journal des Savans, of the year 1660, consisted in a pure spirit of sulphur, wherewith he rubbed his hands, and the parts that were to touch the fire; which burning and cauterising the epidermis, hardened and enabled the skin to resist the fire.

Indeed, this is no new thing: Amb. Pare assures us he had tried it on himself; that after washing the hands in urine, and with unguentum aureum, one may safely wash them in melted lead.

He adds also, that by washing his hands in the juice of onions, he could bear a hot shovel on them while it melted lead.

theology. See Hell.

We read of the sacred fire in the first temple of Jerusalem, which came down from heaven: it was kept with the utmost care, and they were forbidden to carry any strange fire into the temple. This fire is one of the five things which the Jews confess were wanting in the second temple.

The pagans had their sacred fires, which they kept in their temples with the most religious care, and which were never to be extinguished. Numa was the first who built a temple to Fire as a godhead, at Rome, and instituted an order of pontiffs for the preservation of it. See Vestals.

Fire was the supreme god of the Chaldeans; the Magi were worshippers of fire; and the Greeks and Armenians still keep up a ceremony called the holy fire, upon a persuasion that every Easter-day a miraculous fire descends from heaven into the holy sepulchre, and kindles all the lamps and candles there.

Fire kindled spontaneously in the Human Body. See Extraordinary Cases of Burning.

Fire-Barrel. See Fire-Ship, Note (B).

Fire-Bowline. Ibid. Note (D).

Fire-Arrow, in naval artillery, is a small iron dart furnished with springs and bars, together with a match impregnated with sulphur and powder, which is wound about its shaft. It is intended to fire the sails of the enemy, and is for this purpose discharged from a musketoon or swivel-gun. The match being kindled by the explosion, communicates the flame to the sail against which it is directed, where the arrow is fastened by means of its bars and springs. This weapon is peculiar to hot climates, particularly the West Indies, where the sails being extremely dry by reason of the great heats, they instantly take fire, and of course set fire to the masts and rigging, and lastly to the vessel itself.

Fire-Ball, in artillery, a composition of meal-powder, sulphur, saltpetre, pitch, &c. about the bigness of a hand-grenade, coated over with flax, and primed with the slow composition of a fuze. This is to be thrown into the enemy's works in the night-time, to discover where they are; or to fire houses, galleries, or blinds of the besiegers; but they are then armed with spikes or hooks of iron, that they may not roll off, but stick or hang where they are desired to have any effect. See Fire-Balls, and Light-Balls.

Balls of Fire, in meteorology, a kind of luminous bodies generally appearing at a great height above the earth, with a splendor surpassing that of the moon; and sometimes equalling her apparent size. They generally proceed in this hemisphere from north to south with vast velocity, frequently breaking into several smaller ones, sometimes vanishing with a report, sometimes not.

These luminous appearances no doubt constitute one part of the ancient prodigies, blazing stars or comets, which which last they sometimes resemble in being attended with a train; but frequently they appear with a round and well-defined disk. The first of these which we have any accurate account, was observed by Dr Halley and some other philosophers at different places, in the year 1719. From the slight observations they could take of its course among the stars, the perpendicular height of this body was computed at about 70 miles from the surface of the earth. The height of others has also been computed, and found to be various; though in general it is supposed to be beyond the limits assigned to our atmosphere, or where it loses its refractive power. The most remarkable of these on record appeared on the 18th of August 1783, about nine o'clock in the evening. It was seen to the northward of Shetland, and took a southerly direction for an immense space, being observed as far as the southern provinces of France, and one account says that it was seen at Rome also. During its course it appears frequently to have changed its shape; sometimes appearing in the form of one ball, sometimes of two or more; sometimes with a train, sometimes without one. It passed over Edinburgh nearly in the zenith, and had then the appearance of a well-defined round body, extremely luminous, and of a greenish colour; the light which it diffused on the ground giving likewise a greenish cast to objects. After passing the zenith it was attended by a train of considerable length, which continually augmenting, at last obliterated the head entirely; so that it looked like a wedge, flying with the obtuse end foremost. The motion was not apparently swift, by reason of its great height; though in reality it must have moved with great rapidity, on account of the vast space it travelled over in a short time. In other places its appearance was very different. At Greenwich we are told, that "two bright balls parallel to each other led the way, the diameter of which appeared to be about two feet; and were followed by an expulsion of eight others, not elliptical, seeming gradually to mutilate, for the last was small. Between each two balls a luminous ferrated body extended, and at the last a blaze issued which terminated in a point. Minute particles dilated from the whole. The balls were tinted first by a pure bright light, then followed a tender yellow, mixed with azure, red, green, &c.; which, with a coalition of bolder tints, and a reflection from the other balls, gave the most beautiful rotundity and variation of colours that the human eye could be charmed with. The sudden illumination of the atmosphere, and the form and singular transition of this bright luminary, tended much to make it awful; nevertheless the amazing vivid appearance of the different balls, and other rich connective parts not very easy to delineate, gave an effect equal to the rainbow in the full zenith of its glory."

Dr Blagden, in a paper on this subject in the 74th volume of the Philosophical Transactions, has not only given a particular account of this and other meteors of the kind, but added several conjectures relating to the probable causes of them. The first thing which occurred to philosophers on this subject was, that the meteors in question were burning bodies rising from the surface of the earth, and flying along the atmosphere with great rapidity. But this hypothesis was soon abandoned, 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 they do not consist of one single body, but of a train of sulphurous 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. To this hypothesis, which was invented by Dr Halley, Dr Blagden objects that no just explanation is given of the nature of the vapours themselves, the manner in which they are raised up, or in which they can be regularly arranged in straight lines of such vast extent; or how they can be supposed to burn in such rarefied air. "Indeed," (says he) "it is very difficult to conceive how vapours could be prevented, in those regions where there is in a manner no pressure, from spreading out on all sides in consequence of their natural elasticity, and instantly losing that degree of density which seems necessary for inflammation." Besides, it is to be expected, that such trains would sometimes take fire in the middle, and thus present the phenomenon of two meteors at the same time, receding from one another in a direct line.

For these and other reasons this hypothesis of Dr Halley was abandoned, and another substituted in its place. This was, that the meteors we speak of are permanent solid bodies, not rising from the earth, but revolving round it in very eccentric orbits, and thus in their perigee moving with inconceivable rapidity. But the Doctor shows, that even on this supposition, the velocity of such bodies must scarce be one third of that with which fire-balls move, and which has been calculated at upwards of 1000 miles per minute. The hypothesis is likewise liable to a number of other objections which cannot be answered, particularly from the variations in their appearance; for it is impossible to show in what manner one solid and permanent body could assume the appearance of eight or ten, as was the case with the meteor of 1783; nor can it be shown why a body, which in passing over Edinburgh appeared with a disk evidently less than that of the sun, should, in passing over Greenwich, assume the appearance of two bodies, each of which had a disk considerably larger than the apparent disk of that luminary. To obviate, in some measure, objections of this kind, it has been supposed that the revolving bodies are surrounded by a kind of electrical atmosphere by which they are rendered luminous; "but" (says the Doctor) "I think, whoever carefully peruses the various accounts of fire-balls, and especially ours of the 18th of August, when it divided, will perceive that their phenomena do not correspond with the idea of a solid nucleus involved in a subtle fluid, any more than with the idea of another learned gentleman, that they become luminous by means of a contained fluid, which occasionally explodes through the thick solid outer shell."

Another hypothesis, which Dr Blagden has not mentioned, is, that the meteors in question are a kind of bodies which 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 altogether impossible we can have. The only opportunity we 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 we have it not in our power to see or investigate them in the least. As the 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 shows itself as fire; remaining invisible and eluding our researches in every other case.

On this hypothesis we must conclude 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 deficient. This opinion is adopted by Dr Blagden for the following reasons:

1. On account of their prodigious velocity, which is not less than 1200 miles in a minute, and seems incompatible with any other substance we know besides the electric fluid. "This (says he) is perhaps the only case in which the course or direction of that fluid is rendered perceptible to our senses, in consequence of the large scale on which these meteors move."

2. Various electrical phenomena have been observed to attend them, such as lamplight fires feeling upon men, horses, &c., and sparks coming from them, "or the whole meteor itself (adds our author), it is said, have damaged ships, houses, &c., after the manner of lightning." This last circumstance, however, we can believe only of another kind of fire-balls, of which we shall afterwards treat, which keep at a small distance from the earth, or run along its surface; for the great meteors of which we now speak, flying at the distance of 50 or 60, or more miles from the surface of the earth, cannot be less from their apparent size than a mile or a mile and a half in diameter. Such an immense body of electric matter descending on the earth, would by its explosion ruin a large tract of country; and there is no probability that when engendered in such a rare atmosphere it could break through the whole body of grofs and dense air which lies between these regions and the earth, and which we know resists the passage of the electric fluid very strongly. Notwithstanding this, there is no impossibility that the atmosphere may be electrified to a great degree by such a meteor passing over it; and thus electrical appearances may attend these bodies without any actual emission of their substance, as Dr Blagden supposes. "If there be really (says he) any hissing noise heard while the meteors are passing, it seems explicable on no other supposition than that of streams of electric matter issuing from them, and reaching the earth with a velocity equal to that of the meteor, namely, in two or three seconds. Accordingly, in one of our late meteors, the hissing was compared to that of electricity issuing from a conductor. The sparks flying off so perpetually from the body of fire-balls may possibly have some connection with these streams. In the same manner the sound of explosions may perhaps be brought to us quicker than if it were propagated to us by the air alone. Should these ideas be well founded, the change of direction, which meteors seem at times to undergo, may possibly be influenced by the state of the surface of the earth over which they are passing, and to which the streams are supposed to reach. A similar cause may occasion the apparent explosion, the opening of more channels giving new vent and motion to the electric fluid. May not the deviation and explosion which appear to have taken place in the fire-ball of the 18th of August over Lincolnshire, have been determined by its approach towards the fens, and an attraction produced by that large body of moisture?"

The explosion mentioned by our author over Lincolnshire does not seem to have been the only one which happened during the course of this meteor. Several people heard reports after it had vanished; and these were sometimes single and sometimes double. At Edinburgh two reports were heard, the one immediately following the other, at the distance of six or seven minutes after the meteor had passed. These reports no doubt indicated a temporary dissolution of the body; but it is by no means probable that the dissolution could have taken place either on account of the state of the earth or atmosphere. We must consider that both earth and atmosphere are always full of electric fluid; and if there happens to be what is called a deficiency (A), in one of them, the other instantly supplies it. It is impossible, therefore, that either the earth or atmosphere could receive such an immense additional quantity in one part without a vent being provided for it somewhere else. In thunderstorms we naturally conclude that vast quantity of electrical matter is put in motion; but from the effects of lightning it appears that this quantity must be very trifling in comparison with what the meteor we now speak of contained. A violent flash of lightning has been known to perforate a looking-glass, and make only a hole of about an inch diameter. Now we have no reason to suppose that the flash, tremendous as it might appear to our eyes, was any other than an electric spark of an inch in diameter. The meteor, on the other hand, appears not to have been less than a mile in diameter; so that the disproportion between it and a single flash of lightning appears almost beyond calculation; and we may reasonably conclude that it could not have been equalled by 10,000 thunderstorms. Had this amazing body of electric fire descended through the atmosphere and dissipated itself on the fens of Lincolnshire, it must have produced the most violent and unheard-of effects, not only in that place, but probably throughout the whole island. Its dissipation must therefore have been in the higher regions, where there was ample space to receive it; and where its explosion, whatever confusion it might make among the etherial matter itself, could not affect our earth or atmosphere in any remarkable way.

(A) A real deficiency can never happen with regard to the electric fluid in any substance whatever, as is shown at large under the article Electricity, as well as many others in this work. What seems a deficiency is only when the fluid has a tendency to circulate. In this case, as the motion must begin in one place and return from another, the place where it begins seems to be deficient, because the fluid is going away from it; while that from which it returns seems, for a similar reason, to have too much. markable degree. Its re-appearance was owing to the same tendency in the fluid to circulate which had originally produced it; and which probably was the violent earthquake in Calabria and the eruption in Iceland. See Earthquake, no. III.

3. Another argument adduced by Dr Blagden in favour of the electrical origin of fire-balls, is their connection with the aurora borealis, and the resemblance they bear to these phenomena, which are now almost universally allowed to be electrical. "Instances (says he) are recorded, where northern lights have been seen to join, and form luminous balls, darting about with great velocity, and even leaving a train behind them like the common fire-balls. This train I take to be nothing else but the rarefied air left in such an electrified state as to be luminous; and some streams of the northern lights are very much like it." The aurora borealis appears to occupy as high, if not a higher region above the surface of the earth, as may be judged from the very distant countries to which it has been visible at the same time; indeed the great accumulation of electric matter seems to lie beyond the verge of our atmosphere, as estimated by the cessation of twilight. Also with the northern lights a hissing noise is said to be heard in some very cold climates: Gmelin speaks of it in the most pointed terms, as frequent and very loud in the north-eastern parts of Siberia; and other travellers have related similar facts."

4. Our author thinks that the strongest argument for the electrical origin of these meteors is the direction of their course, which is constantly either from the north or north-west quarter of the heavens, or towards it; or, as our author thinks, nearly in the direction of the magnetic meridian. Such a course, however, seems only to belong to the very large fire-balls of which we now speak; the smaller ones, called Falling Stars, being moved in all directions; "perhaps (says the Doctor), because they come further within the verge of our atmosphere, and are thereby exposed to the action of extraneous causes. That the smaller sort of meteors, such as shooting stars, are really lower down in the atmosphere, is rendered very probable by their swifter apparent motion: perhaps it is this very circumstance which occasions them to be smaller, the electric fluid being more divided in more resisting air. But as those masses of electric matter which move where there is scarce any resistance, so generally affect the direction of the magnetic meridian, the ideas which have been entertained of some analogy between these two obscure powers of nature seem not altogether without foundation. If the foregoing conjectures be just, distinct regions are allotted to the electrical phenomena of our atmosphere. Here below we have thunder and lightning, from the unequal distribution of the electric fluid among the clouds; in the loftier regions, whither the clouds never reach, we have the various gradations of falling stars; till, beyond the limits of our corporeal atmosphere, the fluid is put into motion in sufficient masses, to hold a determined course, and exhibit the different appearances of what we call fire-balls; and probably at a still greater elevation above the earth, the electricity accumulates in a lighter and less condensed form, to produce the wonderfully diversified streams and coruscations of the aurora borealis."

The paper from whence these extracts are taken was written before Mr Morgan's account of the non-conducting power of a perfect vacuum made its appearance. An abstract of his arguments on this subject is given under the article Electricity, no. 130—137, and their insufficiency to prove the point intended, is shown under the same article, no. 277. Under that article, we have only mentioned the deficiency in Mr Morgan's argument, without adding any positive proof to the contrary. Such a proof, however, is offered by the meteor in question, or by others of the same nature. Dr Halley, speaking of the fireball of 1719, the height of which he calculated at very little less than 70 miles, expresses his surprise that sound should be propagated through a medium near 300,000 times rarer than the common air, and the next thing to a perfect vacuum. Now it remains, and for ever will remain, to be proved, that Mr Morgan's most perfect vacuum, formed by boiling quicksilver in a tube ever so long, contains a medium more than 300,000 times rarer than the common atmosphere. From Mr Cavallo's experiments * it appears, that when the air is only rarefied 1000 times, the electric light is scarcely visible; so that there is not the least probability that in an aerial medium 300,000 times rarer than the present, if indeed such a medium can exist, there could be any light made visible in the ordinary experiments. We see, however, by the many examples of meteors which have occurred at prodigious heights in the atmosphere, that the electric light in such a rarefied atmosphere is not only visible, but acts as vigorously in every respect as if it were on the surface of the earth. This circumstance therefore affords a complete demonstration of the fallacy of Mr Morgan's argument, and a direct proof that the electric fluid pervades space as completely divested of air as the best artificial vacuum we can make; nay, where it is generally believed by mathematicians that the atmosphere has ceased altogether. His other arguments drawn a priori are still more inconclusive than that we have just mentioned. He tells us, that if a vacuum was a conductor, the whole quantity of electric matter contained in the earth and atmosphere would be perpetually flying off through the regions of infinite space, as being surrounded by a boundless conductor. But even this does not follow, though we should suppose these regions to be an absolute vacuum; for we know that electricity does not fly to a conducting substance merely because it is a conductor, but because it opens a passage to some place whither it has a tendency to go though the conductor was not there. Now, on the present hypothesis, as the conductor would lead to no place to which the electric matter had any previous tendency, we cannot assign any reason why it should acquire a tendency to fly off merely on account of the neighbourhood of a conductor, even though boundless. His other objection (that, on the supposition of a vacuum being capable of conducting electricity, the whole space in the universe would be filled with electric fluid) may be admitted in its fullest extent, without any detriment whatever to science: and indeed, if we allow the electric fluid to be only a modification of the light of the sun, as is rendered very probable under the article Electricity, sect. vi. as well as that of Fire, and many others in various places of this work, work, we must own that the whole universe is filled with it. The meteors in question then will be no other than discharges of electricity from one part of the celestial spaces to another, similar to the discharges between the positive and negative side of an electrified bottle; thus intimating, that a circulation has taken place in the fluid, which the meteor at once completes and puts an end to. See the article Meteorology.

Besides these already just mentioned of such vast magnitude, there are others much smaller and nearer the surface of the earth, rolling upon it, or falling upon it, exploding with violence, as is the case with those which appear in the time of thunder, and frequently produce mischievous effects. One of these is mentioned by some authors as falling in a serene evening in the island of Jamaica; exploding as soon as it touched the surface of the ground, and making a considerable hole in it. Another is mentioned by Dr Priestley as rolling along the surface of the sea, then rising and striking the topmast of a man of war, exploding, and damaging the ship. In like manner we hear of an electrified cloud at Java in the East Indies; whence, without any thunderstorm, there issued a vast number of fire-balls, which did incredible mischief. This last phenomenon points out to us the true origin of balls of this kind, viz. an excessive accumulation of electricity in one part, or a violent tendency to circulate, when at the same time the place where the motion begins is at so great a distance, or meets with other obstacles of such a nature, that it cannot easily get thither. Urged on, however, by the vehement pressure from behind, it is forced to leave its place; but being equally unable to displace the great quantity of the same fluid, which has no inclination to move the same way with itself, it is collected into balls, which run hither and thither, according as they meet with conductors capable of leading them, into some part of the circle. This is even confirmed by an experiment related at the end of Dr Priestley's fifth volume on Air. He relates, that a gentleman having charged, with a very powerful machine, a jar, which had the wire supporting the knob of a considerable length, and palled through a glass-tube, a globe of fire was seen to issue out of it. This globe gradually ascended up the glass-tube till it came to the top of the knob, where it settled, turning swiftly on its axis, and appearing like a red-hot iron ball of three quarters of an inch diameter. On continuing to turn the machine, it gradually descended into the jar; which it had no sooner done, than there ensued a most violent explosion and flash, the jar being discharged and broken at the same time. This experiment, however, is singular in its kind; for neither the gentleman who performed it, nor any other, has yet been able to repeat it. Single as it is, however, we may yet gather from it, that a fire-ball will be the consequence of a very violent electrification of any substance, provided at the same time that the air be in a very non-conducting state, so that the electricity may not evaporate into it as fast as it is collected; for this would produce only lucid streams and flashes, as in the common experiments with the Leyden phial: and it is probably an inattention to this circumstance which has hitherto prevented the repetition of the experiment above-mentioned. The case is the same in thunderstorms, where an excessive accumulation of electric matter always produces fire-balls, the most mischievous kind of lightning, as is explained under that article.

With regard to the uses which fire-balls serve in the system of nature, it is plain that they are the means of preserving the equilibrium in the electric fluid in the atmosphere, which would otherwise produce the most dreadful tempests. Under the article Aurora Borealis, it is shown why there must be a constant current of electric matter through the bowels of the earth from the equator to the poles, and from the poles to the equator through the atmosphere. The great meteors serve for keeping up the equilibrium in this great atmospheric current, while the smaller ones answer a like purpose in the general mass of electric matter dispersed over the surface of the earth, and therefore are seen to move in all directions, as the equilibrium happens to require them in different parts. With regard to those which are observed in the lower regions of the earth, or rolling on the surface of the ground itself, they undoubtedly answer purposes of a similar kind in the lower regions; for as fire-balls in general are produced by a great excess of electricity in one place, there must of course be an equal deficiency in another; and to restore the equilibrium, or, to speak more properly, to prevent a dangerous commotion from taking place throughout the whole mass of electric fluid, the fire-ball breaks forth, and either puts a stop at once to the disturbance by an explosion, or by a silent and invisible evaporation. From some accounts indeed it would seem that even the large celestial meteors detached part of their substance to accomplish this purpose; though, for the reasons already given, it would seem more probable that they operated by electrifying the atmosphere, or setting the fluid contained in it in motion, so as to produce small fire-balls of itself, rather than by detaching any part of their own bodies to such a distance. Dr Blagden, in the paper above quoted, gives an account of an appearance of this kind. It was described in a letter to Sir Joseph Banks from the Abbé Mann, director of the academy at Brussels. "It happened (says the Abbé) at Mariackerke, a small village on the coast, about half a mile west of Oltend. The curate of the village was sitting in the dusk of the evening with a friend, when a sudden light surprised them, and, immediately after a small ball of light-coloured flame came through a broken pane of glass, crossed the room where they were sitting, and fixed itself on the chink of a door opposite to the window where it entered, and there died gradually away. It appeared to be a kind of phosphoric light carried along by the current of air. The curate and his friend, greatly surprised at what they saw, apprehended fire in the neighbourhood; but going out, found that the fire which had come in through the window had been detached from a large meteor in its passage."

Fire-Cocks. Churchwardens in London and within the bills of mortality, are to fix fire-cocks at proper distances in streets, and keep a large engine and hand-engine for extinguishing fire, under the penalty of 10l. flat. 6 Ann. c. 31.

On the breaking out of any fire in London or Westminster, the constables and beadles of parishes shall repair pair to the place with their slaves, and assist in extinguishing it, and cause the people to work for that end, &c.

**Fire-Engine.** See **Steam-Engine.**

**Fire-Flair,** in ichthyology. See **Raja.**

**Fire-Flier,** a species of flies common in Guiana, of which there are two species. The largest is more than an inch in length, having a very large head connected with the body by a joint of a particular structure, with which at some times it makes a loud knock, particularly when laid on its back. The fly has two feelers or horns, two wings, and six legs. Under its belly is a circular patch, which, in the dark, shines like a candle; and on each side of the head near the eyes is a prominent, globular, luminous body, in size about one-third larger than a mustard seed. Each of these bodies is like a living star, emitting a bright, and not small, light; since two or three of these animals, put into a glass vessel, afford light sufficient to read without difficulty, if placed close to the book. When the fly is dead, these bodies will still afford considerable light, tho' it is less vivid than before; and if bruised, and rubbed over the hands or face, they become luminous in the dark, like a board smeared over with English phosphorus. They have a reddish-brown or chestnut colour; and live in rotten trees in the day, but are always abroad in the night. The other kind is not more than half as large as the former: their light proceeds from under their wings, and is seen only when they are elevated, like sparks of fire appearing or disappearing at every second. Of these the air is full in the night, tho' they are never seen in the day. They are common not only in the southern, but in the northern parts of America, during the summer.

**Fire-Lock,** or **Fufl,** a small gun which fires with a flint. It is distinguished from an old musket, or match-lock, which was fired with a match. The firelock is now in common use in the European armies.

**Fire-Philosophers,** or **Philosophi per ignem,** a fanatical sect of philosophers who appeared towards the close of the 16th century, and made a figure in almost all the countries of Europe. The distinguishing tenet from which they derived this appellation was, that the intimate essences of natural things were only to be known by the trying efforts of fire, directed in a chemical process. They were also called **Theosophists,** from their declaring against human reason as a dangerous and deceitful guide, and representing a divine and supernatural illumination as the only means of arriving at truth: they were likewise denominated **Paracelsists,** from the name of Paracelsus, the eminent physician and chemist, who was the chief ornament and leader of this extraordinary sect. It was patronized in England by Robert Flood or Fludd, who endeavoured to illustrate the philosophy of Paracelsus in a great number of treatises; in France, it was zealously propagated by Riviére; in Denmark, by Severinus; in Germany, by Kunrath, an eminent physician of Dresden; and in other countries by warm and successful votaries, who assumed a striking air of piety and devotion, and professed to themselves no other end than the advancement of the divine glory, and the restoration of peace and concord in a divided church: accordingly they were joined by several persons eminent for their piety, and distinguished by their zeal for the advancement of true religion. One of the most celebrated of these was Daniel Hoffman, professor of divinity in the university of Helmstadt, who, availing himself of some unguarded passages in the writings of Luther, extravagantly maintained, that philosophy was the mortal enemy of religion; that truth was divisible into two branches, the philosophical and theological; and that what was true in philosophy was false in theology. Hoffman was afterwards obliged, by the interposition of Henry Julius, duke of Brunswick, to retract his invectives against philosophy, and to acknowledge in the most open manner the harmony and union of sound philosophy with true and genuine theology.

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

The late ingenious Dr Franklin, having recounted the inconveniences and advantages of fire-places in common use, proposes a new contrivance for this purpose, called the **Pennsylvania fire-place.** 1. This machine consists of a bottom-plate or hearth-piece (see fig. 1.) with a rising moulding before for a fen-Plate, two perforated ears F, G, for receiving two screw-rods; a long air-hole a a, through which the outward air passes into an air-box; and three smoke-holes represented by dark squares in BC, thro' which the smoke descends and passes away; besides, double ledges for receiving between them the lower edges of the other plates. 2. A back plate without holes, and furnished with a pair of ledges to receive, 3. The two side-plates, each of which has a pair of ledges to receive the side-edges of the front plate, with a shoulder on which it rests; two pair of ledges to receive the side-edges of the two middle plates which form the air-box, and an oblong air-hole near the top, through which the air warmed in the box is discharged into the room, and a wing or bracket as H, and a small hole as R, for the axis of the regilter to turn in. See fig. 2. which represents one of these plates. 4. An air-box, composed of the two middle plates D E and FG, fig. 3. and 4. The first has five thin ledges or partitions cast on it, the edges of which are received into 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. 5. A front-plate, which is arched on the under side, and ornamented with foliages, &c. 6. A top plate, with a pair of ears M, N, (fig. 5.) 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 2½ inches.

All these plates are of cast iron; and when they are all in their proper places, they are bound firmly together by a pair of slender rods of wrought iron with screws, and the machine appears as in fig. 5. There are also two thin plates of wrought iron, viz. 7. The shutter, which is of such a length and breadth as to close well the opening of the fire-place, and serving to blow blow up the fire, and to secure it in the night. It is raised or depressed by means of two brass knobs, and slides in a groove left between the foremost ledge of the side plates and the face of the front plate. 8. The register, which is placed between the back plate and air-box, and furnished with a key; so that it may be turned on its axis, and made to lie in any position between level and upright. The operation of this machine, and the method of fixing it, may be understood by observing the profile of the chimney and fire-places in fig. 6. M is the mantle-piece or breast of the chimney; C the funnel; B the false back, made of brick-work in the chimney, four inches or more from the true back, from the top of which a capping is to be made over to the breast of the chimney, that no air may pass into the chimney except that which goes under the false back, and up behind it; E the true back of the chimney; T the top of the fire-place; F the front of it; A the place where the fire is made; D the air-box; K the hole in the side plate, thro' which the warmed air is discharged out of the air-box into the room; H the hollow, formed by removing some bricks from the hearth under the bottom plate filled with fresh air, entering at the passage I, and ascending into the air-box through the air-hole in the bottom plate near G, the partition in the hollow, designed to keep the air and smoke apart; P the passage under the false back, and part of the hearth for the smoke; and the arrows in the figure show the course of the smoke. The fire being made at A, the flame and smoke will ascend, strike the top T, and give it a considerable heat; the smoke will turn over the air-box, and descend between it and the back plate to the holes near G in the bottom plate, heating in its passage all the plates of the machine; it will then proceed under and behind the false back, and rise into the chimney. The air of the room contiguous to the several plates, and warmed by them, becomes specifically lighter than the other air in the room, and is obliged to rise; but being prevented by the closure over the fire-place from going up the chimney, is forced out into the room, and rising by the mantle-piece to the ceiling, is again driven down gradually by the steam of newly-warmed air that follows; and thus the whole room becomes in a little time equally warmed. The air also, warmed under the bottom plate and in the air-box, rises and comes out of the holes in the side plates, and thus warming and continually changing the air of the room. In the capping of the chimney a square opening for a trap-door should be left for the sweeper to go up: the door may be made of slate or tin, and so placed, that by 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. It will also be convenient to have a small hole, about five or six inches square, cut near the ceiling thro' into the funnel, and provided with a shutter; by occasionally opening which, the heated air of the room and smoke of tobacco, &c. may be carried off without incommending the company.

For a farther account of the manner of using this fireplace, the advantages attending it, answers to objections, and directions to the brick-layer in fixing it, the curious reader may consult Franklin's Letters and Papers on Philosophical Subjects, p. 284—318. edit. 1769.

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

**Fire-Reeds.** See the next article, Note (c.)

**Fire Ship,** an old vessel filled with combustible materials, and fitted with grappling irons to hook, and set fire to, the enemies ships in battle, &c.

As there is nothing particular in the construction of this ship, except the apparatus by which the fire is instantly conveyed from one part to another, and from thence to the enemy, it will be sufficient to describe the fire-room, where these combustibles are enclosed, together with the instruments necessary to grapple the ship intended to be destroyed.

The fire-room is built between decks, and limited on the after part by a bulk-head, L, behind the mainmast, from which it extends quite forward, as represented in Plate CXCIII. The train inclosed in this apartment is contained in a variety of wooden troughs, D, G, which intersect each other in different parts of the ship's length; being supported at proper distances by cross-pieces and stanchions. On each side of the ship are six or seven ports, H, about 18 inches broad and 15 inches high; and having their lids open downward, contrary to the usual method.

Against every port is placed an iron chamber (A), which, at the time of firing the ship, blows out the port-lid, and opens a passage for the flame. Immediately under the main and fore-shrouds is fixed a wooden funnel M; whose lower end communicates with a fire-barrel (B), by which the flame passing thro'

---

(a) The iron-chambers are 10 inches long and 3.5 inches diameter. They are breeched against a piece of wood fixed across the ports, and let into another a little higher. When loaded, they are almost filled with corn-powder, and have a wooden tommon well driven into their muzzles. They are primed with a small piece of quick-match thrust through their vents into the powder, with a part of it hanging out. When the ports are blown open by means of the iron-chambers, the port-lids either fall downward, or are carried away by the explosion.

(b) The fire-barrels ought to be of a cylindrical form, as most suitable to contain the reeds with which they are filled, and more convenient for flowing them between the troughs in the fire-room. Their inside chambers should not be less than 21 inches, and 30 inches is sufficient for their length. The bottom parts are first well stored with the funnel is conducted to the shrouds. Between the funnels, which are likewise called fire-trunks, are two scuttles, or small holes in the upper deck, serving also to let out the flames. Both funnels must be stopped with plugs, and have fail-cloth or canvas nailed close over them, to prevent any accident happening from above to the combustibles laid below.

The ports, funnels, and scuttles, not only communicate the flames to the outside and upper-works of the ship and her rigging; but likewise open a passage for the inward air, confined in the fire-room, which thereby expanded so as to force impetuously through those outlets, and prevent the blowing up of the decks, which must of necessity happen from such a sudden and violent rarefaction of the air as will then be produced.

On each side of the bulk-head behind is cut a hole L, of sufficient size to admit a trough of the same dimensions as the others. A leading trough, L1, whose foremost end communicates with another trough within the fire-room, is laid close to this opening, from whence it extends obliquely to a fall-port I, cut thro' the ship's side. The decks and troughs are well covered with melted rosin. At the time of the firing either of the leading troughs, the flame is immediately conveyed to the opposite side of the ship, whereby both sides burn together.

The spaces N, O, behind the fire-room, represent the cabins of the lieutenant and master, one of which is on the starboard, and the other on the larboard side. The captain's cabin, which is separated from these by a bulk-head, is exhibited also by P.

Four of the eight fire-barrels are placed under the four fire-trunks; and the other four between them, two on each side the fire-scuttles, where they are securely cleated to the deck. The longest reeds (c) are put into the fore and aft troughs, and tied down: the shortest reeds are laid in the troughs athwart, and tied down also. The bavins (d), dipped at one end, are tied fast to the troughs over the reeds, and the curtains are nailed up to the beams, in equal quantities, on each side of the fire-room.

The remainder of the reeds are placed in a position nearly upright, at all the angles of every square in the fire-room, and there tied down. If any reeds are left, they are to be put round the fire-barrels, and other vacant places, and there tied fast.

Instructions to prime.

Take up all your reeds, one after another, and throw a little composition at the bottom of all the troughs under the reeds, and then tie them gently down again: next throw composition upon the upper part of the reeds throughout the fire-room; and upon the said composition lay double quick-match upon all the reeds, in all the troughs: the remainder of the composition throw over all the fire-room, and then lay your bavins loose.

Cast off all the covers of the fire-barrels, and hang the quick-match loose over their sides, and place leaders of quick-match from the reeds into the barrels, and from thence into the vent of the chambers, in such a manner as to be certain of their blowing open the ports, and setting fire to the barrels. Two troughs of communication from each door of the fire-room to the fall-ports, must be laid with a strong leader of quick-match,

with short double-dipped reeds placed upright; and the remaining vacancy is filled with fire-barrel composition well mixed and melted, and then poured over them. The composition used for this purpose is a mass of sulphur, pitch, tar, and tallow.

There are five holes, of three-fourths inch in diameter and three inches deep, formed in the top of the composition while it is yet warm; one being in the centre, and the other four at equal distances round the sides of the barrel. When the composition is cold and hard, the barrel is primed by filling those holes with fuse-composition, which is firmly driven into them, so as to leave a little vacancy at the top to admit a strand of quick-match twice doubled. The centre-hole contains two strands at their whole length, and every strand must be driven home with mealed powder. The loose ends of the quick-match being then laid within the barrel, the whole is covered with a dipped curtain, fastened on with a hoop that slips over the head of the barrel, to which it is nailed.

The barrels should be made very strong, not only to support the weight of the composition before firing, when they are moved or carried from place to place, but to keep them together whilst burning: for if the flames are too light and thin, so as to burn very soon, the remaining composition will tumble out and be dissipated, and the intention of the barrels, to carry the flame aloft, will accordingly be frustrated.

The curtain is a piece of coarse canvas, nearly a yard in breadth and length, thickened with melted composition, and covered with saw-dust on both sides.

(c) The reeds are made up in small bundles of about a foot in circumference, cut even at both ends, and tied together in two places. They are distinguished into two kinds, viz. the long and short; the former of which are four feet, and the latter two feet five inches in length. One part of them are singly dipped, i.e. at one end; the rest are dipped at both ends in a kettle of melted composition. After being immersed about seven or eight inches in this preparation, and then drained, they are sprinkled over with pulverised sulphur upon a tanned hide.

(d) The bavins are made of birch, heath, or other brushwood, which is tough and readily kindled. They are usually two or three feet in length, and have all their bush-ends lying one way, the other ends being tied together with small cords. They are dipped in composition at the bush-ends, whose branches are afterwards confined by the hand, to prevent them from breaking off by moving about; and also to make them burn more fiercely. After being dipped in the same manner as the reeds, they also are sprinkled with sulphur. match, four or five times double: also a crofs-piece to go from the fally-port, when the ship is fired, to the communication trough, laid with leaders of quick-match, that the fire may be communicated in both sides at once.

What quick-match is left place so that the fire may be communicated to all parts of the room at once, especially about the ports and fire-barrels, and see that the chambers are well and fresh primed. [N. B. The port-fire used for firing the ship, burns about 12 minutes. Great care must be taken to have no powder on board when the ship is fired.]

The sheer-hooks (represented by A) are fitted so as to fall on the yard-arms of the fire-ship, where they hook the enemy's rigging. The fire-grapplings, (B,) are either fixed on the yard-arms, or thrown by hand, having a chain to confine the ships together, or fasten those instruments wherever necessary.

When the commanding officer of a fleet displays the signal to prepare for action, the fire-ships fix their sheer-hooks, and dispose their grappings in readiness. The battle being begun, they proceed immediately to prime, and prepare their fire works. When they are ready for grappling, they inform the admiral thereof by a particular signal.

To avoid being disabled by the enemy's cannon during a general engagement, the fire ships continue sufficiently distant from their line of battle, either to windward or to leeward.

They cautiously find the openings or intervals of the line, where they would be directly exposed to the enemy's fire, from which they are covered by lying on the opposite side of their own ships. They are attentively to observe the signals of the admiral or his seconds, in order to put their designs immediately in execution.

Although no ship of the line should be previously appointed to protect any fire-ship, except a few of the smallest particularly destined to this service, yet the ship before whom she passes in order to approach the enemy, should escort her thither, and affix her with an armed boat, or whatever succour may be necessary in her situation.

The captain of the fire-ship should himself be particularly attentive that the above instructions are punctually executed, and that the yards may be so braced when he falls along-side of the ship intended to be destroyed, that the sheer-hooks and grappings fastened to the yard-arms, &c. may effectually hook the enemy. He is expected to be the last person who quits the vessel; and being furnished with every necessary assistance and support, his reputation will greatly depend on the success of his enterprise.

Lambent Fires, as the shining of meat at certain seasons, the luminousness of the sea, of insects, vapours, &c. See the articles Light, Pholas Medusa, Nereis, Fire-Flies, Glow-Worms, &c.

Port-Fire. See Port-Fire.

Spur-Fire. See Spur-Fire.

Fire-Works, are preparations made of gunpowder, sulphur, and other inflammable and combustible ingredients, used on occasion of public rejoicings and other solemnities.

The invention of fire-works is by M. Mahudel attributed to the Florentines and people of Sienna; who

found out likewise the method of adding decorations to them of statues, with fire issuing from their eyes and mouths.

The art of preparing and managing these is called pyrotechny. See Pyrotechny.