Fire, is that subtle, invisible cause, which penetrates both solid and liquid matters with extreme facility, and renders them hot to the touch. It is also the chief agent, by which the composition and decomposition of natural bodies is generally effected; so that, without fire, the animal and vegetable kingdoms would cease to exist.

Various opinions have been maintained concerning the nature and properties of fire; for an account of which we are obliged to refer the reader to the works of Boyle, Newton, and Scheele ; as we propose to give a few illustrations connected with this subject, under the article Heat.

Though designed to be subservient to the most useful purposes, fire frequently becomes a scourge to mankind; and, unless it be timely discovered, lays whole streets and towns in ashes. Hence the securing of houses and other buildings against this devouring element, has ever formed an important ob-ject of inquiry, while it has exercised the ingenuity of intelligent men : we shall briefly state a few of the most remarkable experiments, together with the result or success which has attended them.

Dr. Hales first proposed a plan of covering the floors of houses with earth. The thicker the mould is laid on the floors, the greater is the security. He supposes that the depth of an inch will be amply sufficient; though he recommends to lay a deeper coat on the stairs; because fire, in general, ascends by means of stair-cases with the greatest velocity,

A patent was granted in April 1773, to David HartlEy, Esq. of Golden-square, for his method of securing buildings and ships against fire. See our first vol. P. 385.

Lord MaHon has likewise in-rented a very simple and effectual mode of securing every kind of building against all danger of fire : he divides it into three parts, name-ly, under-flooring, extra-lathing, and inter-securing. The first part or method, is either single or double. In single under-flooring, a common strong lath, one quarter of an inch thick, should be nailed against each side of every joist and main-timber, supporting the floor which is to be secured. Similar laths are then to be nailed on the whole length of the joists, the ends of which abut against each other. The top of each lath or fillet, ought t0 be an inch and a half below the top of the joists or timbers, against which they are nailed, so as to form a small ledge on every side. When these fillets are nailed on, they should be laid in a rough plaster, which ought to be spread on the tops of such fillets, so as to leave no vacant space between them and the joists. Short pieces of common laths are next to be nailed closely together, in a direction contrary to that of the joists ; the ends of the former are to rest on the fillets, and to be well bedded in rough plaster, but not fastened with nails. They are next to be coated once with the plaster, which is to be spread over them to the tops of the joists. In double-flooring, the fillets and short pieces of laths are applied in the manner already described ; the coat of rough plaster ought, however, in this method, to be somewhat more than half as thick as that in single-flooring.— While the rough plaster is laying on, some additional short pieces of laths are to be inserted between the joists upon the first coat, as closely to each other as possible, and in the same direction as the first layer of laths. Over this second layer of short laths, another coat of rough plaster should be spread, which ought to be trowelled level with the tops of the joists.

As soon as the plaster-work between the joists is perfectly dry, it should be inspected, in order to ascertain whether there be any small cracks, especially next to the joists. Should any occur, it will be requisite to close them, by washing them over with a brush, wetted with mortar-wash, which may be prepared by mixing two measures of quick-lime and one of sand in a pail, and tempering the whole with water, till it acquire* the consistence of a thin jelly.

Previously to laying down the flooring-boards, a small quantity of dry common sand should be strew -ed over the plaster-work, and struck smooth with an hollow rule in the same dire6tion as the joists are laid, so that it may lie rounding between each pair of joists. Particular attention should be paid to the piasterplaster-work and sand, that they be perfectly dry before the boards are laid, lest the latter become in-fected with the dry-rot. The mode of under-flooring may be successfully applied to a wooden staircase ; but no sand is then to be laid upon the plaster-work. The method of extra-lathing may be practised on ceiling-joists, sloping-roofs, and wooden partitions.

The third method, namely, inter-securing, is similar to that of under-flooring ; but no sand is afterwards to be laid over it. Inter-securing is applicable to the same parts of a building as the method of extra-lathing ; but it is seldom necessary to be employed. Lord Mahon made several experiments, which shew the utility of this invention ; but we can only refer the inquisitive reader to the 68th volume of the "Philosophical Trans-actions of the Royal Society," for 1778 ; where he will find a satis-factory account of the manner of preparing the mortar, as well as the result of numerous trials made by the inventor. - See also Coun-Try-hOuses and FiRe-pRoof.

The most expeditious way of extinguishing fire is a matter of equal importance, as the security of buildings from that destructive •gent. Hence various machines, and chemical preparations, have been invented by ingenious men, in order to promote so useful an object; one of the earliest contrivances was a barrel, filled with certain ingredients, first proposed by M.. Fuchs, a German physi-cian, in the year 1734; and which effectually answered the purpose for which it was designed. - A si-milar invention was introduced into this country by a Mr. Zachary GreYl, whose machines were made of wood, and contained only water ; they were exhibited before several of the nobility, but did not meet with encouragement. In the year 1761 Dr. Godfrey produced certain vessels which in every re-spect succeeded. They are supposed to have been an improvement on Mr. Greyl's, were constructed with wood, and filled with a chemical liquor, consisting of water, oil of vitriol, and sal-am-moniac. When thrown into rooms and other places that were purposely set on fire, they burst, and by their explosion completely extinguished the flames : it is to be observed, that they were useless alter the roof had fallen in. These contrivances, however, are evidently more calculated for ships, than to be employed on land; as they would be of great service for suppressing fires in vessels at sea, and might be considered as necessary a part of their cargo as naval stores, or ammunition.

In the 23d vol. of "Annals of Agriculture," Mr.WILLIAM Knox, a merchant of Gothenburg, in Sweden, states that he has made a variety of expeiiments for extinguishing fire by means of such sub-stances as are cheap and easily procured. He divides them into simple and compound solutions. In the former class, he proposes to add to 75 gallons of water, 9 gallons of the strongest solution of wood-ashes ; or 6 gallons of the finest pulverized pot-ashes; or 81/2 gallons of common salt, well dried, and finely beaten; or 8 1/2 gallons of green vitriol or copperas, thoroughly dried and finely puiverized; or 11 1/4 gallons of the strongest herring-pickle; or 9 gallons of alum reduced to powder; or 19 gallons of clay, perfectly dried, well beaten, and carefully sifted.

Among the compound solutions,

Mr. Knox recommends to mix 7.0 gallons of water with 10 quarts of.clay, 10 quarts of vitriol, and 10 quarts of common salt; or a similar quantity of water, with 18 quarts of the strongest solution of wood-ashes and 18 quarts of line clay reduced to powder; or the same proportion of water, with 15 quarts of red-ochre, or the residuum of aquafortis, and 15 quarts of common salt; or, lastly, to mix 15 quarts of the strongest herring-pickle, and 15 quarts of red-ochre, with 75 gallons of water. - All these different solutions, Mr. Knox remarks, are equally efficacious in extinguishing fire; but he prefers the compounds, as being the "surest and most powerful for that purpose."

Another of the various inventions for extinguishing fire by chemical means, deserving of notice, is the composition prepared by M. Von Aken, and which consists of the following ingredients ; lbs. Burnt alum - - - - 30 Green vitriol in powder - 40 Cinabrese, or red-ochre, } pulverized - J Potters, or other clay, | finely pounded and sifted } Water.....630

With 40 measures of this liquor an artificial fire, which would have required the labour of twenty men, and ,1500 measures of common water, was extinguished, under the direction of the inventor, by three persons. The price of this compound solution is estimated at one halfpenny per pound.

Water Engines for extinguishing fire. These are either forcing or lifting pumps ; and as they are made to move with great velocity, their execution principally depends

With 40 measures of this liquor an artificial lire, which would have required the labour of twenty men, and 1500 measures of common water, was extinguished, under the direction of the inventor, by three persons. The price of this compound solution is estimated at one halfpenny per pound.

Water Engines for extinguishing fire. These are either forcing or lifting pumps; and as they are made to move with great velocity, thcir execution principally depends on the length of their levers, and the force with which they are worked.

Various engines have been contrived, from which we have selected the following, as they are the most ingenious, and at the same time calculated to produce the greatest effects. - In the year 1785, the silver medal and twenty guineas were conferred by the "Society for the Encouragement of Arts," etc." on Mr. Furst, as a reward for his contrivance t6 increase the effect of engines in extinguishing fires; of which the following is a short description : From a platform rises an upright pole or mast, of such height as may be judged necessary; a gaft slides upon it in an ascending direction, and along both is conveyed the leather hose from the engine. The branch, or nose-pipe of the engine, projects at the extremity of the gaft; towards which an' iron frame is fixed, whence two chains are suspended: and from these hang ropes, which serve to give an horizontal direction to the branch; while other ropes, that run through proper pullies, and are thus conveyed down the mast, serve likewise to communicate a vertical motion to it. By these means, the branch or nose-pipe of the engine is conducted into the window of any room where the fire more immediately rages; and the effect of the water discharged is applied in the most efficacious manner to the extinguishing of the flames.

A patent was granted in January 1790, to Mr. JosEph Bramah, of Piccadilly, and to Mr. Thomas Dickenson, of Bedworth Close, in the county of Warwick, for a new improved engine on a rotative principle. The merits of this machine depend on its having two wheels or cylinders of brass, or any other metal l one of which is of a greater, and the other of a smaller diameter, in any proportion re-quired; both are nearly of equal length, but may be inereased or decreased, according to the purpose to which the machine is ap-plied. As soon as the larger waeel is fixed, the smaller one is placed within it, and is fastened on an axis, so as to turn in a rotative direction round its centre; the smaller wheel being thus stationed be occasionally fixed, and the forger one moved in the same direction round the smaller one: the former of these, however, is pre-ferable in all cases. At each end of the larger wheel there is flanch, to which are screwed two plates, or caps inclosing its ends, and into which the extremities of the smaller wheel are inserted, so as to render water-tight: through these caps passes the axis of the inner cylinder, in order to communicate motion from without. - Or the inner wheel may be applied so as to give motion, by its external end or ends, to any other engine or machine connected with it.— These are the component parts of Messrs. BRAMAH's and Dickenson's patent engines; for a more particular account of which, we refer the reader to the 2d vol. of Repertory of Arts and Mann-ires, where he will find a minute account of the machinery, and the effects it is calculated to produce.

A patent was likewise granted in December 1792. to Mr. Charles SimpKin, or Oxford-street, engine-maker ; for his improvements in all kinds of machines for extinguishing fire. - This invention consists in exploding or removing the valves both from that part of the cylinder, where the vacuum is made by the piston or fly, and from beneath the air-vessel; and in making use of valves, by the application of certain filtering chambers, with partitions or divi-sions, to preserve the effect of the valves, during the use of any improper fluid. These filtering chambers are to be placed between the drawing valves, and the strainer in common use, on the suction-pipe. The partitions in the chambers may be of fine wire-work, or of any other substitute, that will act as a first and second filtration in the chamber.

The design of this invention is, to render the valves more free of access, and to prevent the necessity of opening any other parts of the engine, except the chambers containing the valves; by which means the effect of the machine is increased, and consequently the fire may be more easily extinguished.

To these different contrivances we shall add the American Fire-engine, of which we have given an accurate engraving. It was invented by Mr. Benjamin Dearborn, who communicated it to the American Academy of Arts and Sciences, from whoseMemoirs for 1/94, we extrat the following particulars:

Description of the Plate representing the American Fire-engine, on a new construction.

Fig. 1. A B, and C D, are the edges of two planks, confined together by four bolts. - a b, and c d, are two cylindrical barrels, in each of which a piston, with a valve, is fastened to the spear e, and is moved up and down alternately by the motion of the arm; E E. Beneath each barrel a hole is made through the plank A B, which is covered with a valve. The arms E E, are suspended on the common centre J': there are also arms parallel to these on the opposite side ; g g are the ends of handles which are fastened across the ends of the arms. At h, a bolt goes across, from arm to arm, to which the piece i, /;, is affixed, and on which it plays; the lower end of this piece is fastened to the top of the spear e. - G, /, f, is a standard for the purpose of supporting the arms, to which there is a correspondent one on the opposite side; both are notched into the edges of the planks, where they are secured by a bolt, which passes through them at /, and has a nut or fore-lock on the opposite side. H I, H I, are square braces, answering the purpose of ducts, through which the water ascends from the barrels, passing through the plank at m. - K L, K L, are irons in the form of a staple, in order to confine the braces : the lower ends of these irons meet, and are secured by a bolt, passing through them, and M N, no, which is a piece that goes up through a mortice in the centre of the planks. This piece is square from the lower end, till it reaches the top of the braces 5 whence they become cylindrical to the top, the upper end being perforated sufficicendy low down, in order to communicate with the braces. O, P, is an iron ring, that surrounds the tube, and has two shanks which ascend through the head, with screws on the top at p, q: - r, s, is a ferule nailed round the tube.

Fig. 1. is the same engine; the arms and standards being taken off, in order to delineate more clearly the mode of securing the braces ; an object which is completely ef-feted by a wedge driven into the mortice a : beneath the upper plank b, is a hole for admitting a passage to the bolt, which secures the standards. In this figure, a side view of the head is given, with the pipe in a perpendicular direction.

The machine is confined within a box, set on wheels, as in the common fire-engines. The whole is made of wood, excepting the spears of the pumps, and a few bolts, etc. The advantages of this machine are, that it can be made in any place where common pumps are manufactured; the -interior work will not exceed one-fourth of the price of those which are con-structed on the usual plan ; and that they are incomparably more easy to work, than the common ones; circumstances which strongly recommend the American fire-engine to the attention of the public.

On the breaking out of a fire, all constables are enjoined, by sever ral acts of parliament, to repair to the place; to use every exertion for extinguishing the flames; and to cause people to work, etc. - By the 10 Ann, c. 14, no action shall be commenced against any person in whose house or chamber a fire shall break out accidentally ; but, if such fire happen through the negligence of any servant, the latter incurs a penalty of 1001. to be distributed among the sufferers ; and, in default of payment, he is to be imprisoned for 18 months, during which time he is to be kept to hard labour. - The wilful setting of fire to any house, out-house, or other building, is felony without benefit of clergy. - See GunPowder