The most suitable and convenient material for extinguishing fire is water; but when that cannot be speedily obtained in sufficient abundance, it has been proposed to increase its extinguishing property by the addition of various substances. M. Van Aken, a Swede, employed an antiphlogistic composition of water holding in solution sulphate of iron, sulphate of alumine, red oxide of iron, and clay, with which he performed several successful experiments. Some persons have recommended the employment of simple solutions of either of the following substances - alum, common salt, pearl-ash, and several other salts and alkalies. Other experimentalists, on the contrary, especially M. Van Marum, have contended, with much apparent truth, that water alone, when properly and judiciously applied, is nearly as efficacious in extinguishing fire as any of the above compounds. Carbonic acid gas, sulphuric acid gas, and steam, have likewise been suggested as applicable to the extinction of fire; there is, however, much practical difficulty, and great inconvenience in employing either of these substances for such a purpose; with respect to the latter, some extensive and well-conducted experiments, recently performed by Mr. Waterhouse, at Preston, in Lancashire, have shown that steam will speedily extinguish moderately small bodies of flame, but does not possess the power of preventing a low or charring combustion, and that steam impelled against a large fire increases the violence of the combustion in a remarkable degree. Water, however, is so universally diffused, that all other modes of extinguishing fires have fallen into disuse. There are many ways of applying this fluid to the purpose now under review, the most useful of which we proceed briefly to describe. The simplest contrivance for extinguishing fires, is by means of an elevated reservoir or cistern, a pipe from which proceeds through all the floors of the building, with a cock and screwed nozle in each, to any of which a flexible hose and director can be affixed. On turning the cock, a jet of water ..rushes out with a force proportionate to the height of the reservoir, which can be thrown into that part of the premises where the fire is situated. This arrangement is particularly useful in large manufactories or warehouses. The principal advantage of this plan, is the great facility with which one person can apply this remedy, the labour having been previously performed.

If the fire is so extensive as to require more water for its extinction than is contained in the reservoir, the supply must be maintained by pumping. In lieu of the reservoir and system of pipes, some persons prefer fixed pumps, drawing their supply of water from a well. The engraving on the preceding page represents a stationary fire-pump of this description, as erected in various places by the late Mr. Russell, of St. John Street, London. It consists of a lifting-force pump, with an air-vessel to equalize the stream between the strokes, placed in a deep well. The nozle of the pump is screwed for attaching one or more lengths of leather hose, according to the distance of the fire; the handle is forked to allow several hands to work the pump. The advantages of this and other kinds of stationary engines, consist in the promptness with which they can be got into action, and the certainty of obtaining a sufficient supply of water: one disadvantage is, that their usefulness is confined to a comparatively limited space.

In some late experiments, one of these pumps, erected at Aldgate, delivered a stream of water with considerable force at the distance of sixteen hundred feet from the source of supply.

Of all the portable contrivances for extinguishing fires, perhaps that invented by Capt. Manby is the most convenient, and is very ingenious. This apparatus consisted of a copper vessel, two feet long, and eight inches in diameter, capable of holding four gallons. A metal tube, a quarter of an inch in diameter, passed internally from the top to within half an inch of the bottom of the vessel, furnished at the top with a stop-cock and jet-pipe one-eighth of an inch in diameter. Three gallons of a saturated solution of pearl-ash in water being put into one of these vessels, the jet-pipe was removed, and a condensing syringe afforded in its place; as much air as possible was then pumped into the space remaining above the fluid: the stop-cock was then turned, and the condensing syringe exchanged for the jet-pipe. In this state the apparatus formed the well-known artificial fountain in pneumatics; on turning the cock, the elasticity of the condensed air reacting on the surface of the fluid, forces it out at the nozle in the form of a violent jet.

Six of these vessels were placed in a light hand-cart, with which a man could run at a good speed.

On reaching the fire the man takes one of the charged vessels from the cart, and slings it in front of him by a strap passing over his shoulders; he then enters the building, and placing himself as close as possible to the fire, turns the cock, and discharges the contents of the vessel on the flames; by the time the first vessel is expended, others will have been conveyed to the man, who discharges them in succession. All fires, even the greatest, have small beginnings, and when early discovered, are easily kept under or suppressed. Capt. Manby's fire-cart appears well adapted to check the progress of fires, if not by entirely suppressing them, yet by keeping them within the range of easy extinction by more powerful means, which cannot be so expeditiously applied.

Fire-engines are now common in every civilized country; the several kinds of these useful machines having been already fully described, it will only be necessary in this place to offer a few practical remarks on their management. In bringing up, placing, and setting a fire-engine to work, great judgment is requisite, and much will always depend upon the acquaintance of the parties employed with the duty they have to perform. Great activity is required in combination with skilfulness; six good hands will, at any time, get a large fire-engine to work through two or three forty-feet lengths of hose in about two minutes, supposing water to be at hand. An engine being set to work, its efficient performance will depend entirely upon the manner in which the stream of water is directed. The old method was to throw the water into the windows at random; latterly, however, a more rational mode of operating has been adopted, and one, the advantage and efficacy of which was strikingly exemplified by the experiments of M. Van Marum, before alluded to.