Mr. Frost's floors have many recommendations, and his cement affords a very convenient mode of protecting various parts of buildings from the action of fire.

Mr. Farrow, of Great Tower-street, London, took out a patent a few years since for a new method of constructing fire-proof buildings, a large model of which was erected in Mark-lane, for public inspection. The walls are of coarse brick or stone, built in the usual manner. The joists are of wrought iron; they are formed with a lateral projecting flange on each side, upon which are laid, from joist to joist, a series of flat stones, and of sufficient thickness (from two to two and a half inches,) to lie flush with the upper edge of the joist, forming a level floor of stone interlined with iron: it may be used in this state, or covered with planks, according to the purposes of the apartment. The ends of the joists are turned down and let into bond stone laid upon the walls, and cemented or run in with lead, which, with the weight of the walls, continued upward, takes off the elasticity of the iron, so as to enable the joists to carry almost any weight, and at the same time ties the walls together in such a manner as to render it impossible for them to separate.

The boarded floors are grooved into the edge of the joists about half an inch, and when dowelled, will require very little fastening down.

But where it is necessary, a stub is let into the stone floor, and screwed to the edge of the board; there are, therefore., no nails necessary, nor any other fastenings visible when the floors are finished. The under part of the stone is stabbed or made rough, so as to form a good key for the ceiling, therefore no laths are necessary, and the whole floor occupies no more than from four to five inches in depth. A roof is the same; and, being covered with mastic, is, according to the statement of the patentee, the cheapest roof ever invented, with the important advantages of being fire, air, and waterproof. These floors have been successfully employed in some sugar refineries, and other premises liable to accident from fire, and are admirably adapted to prevent this calamity. Having thus briefly described some of the most important facts relative to floors, we proceed to state that the most material part of all buildings, so far as prevention of fire is concerned, is the staircase, - for this part, above all others, acts as a conductor, and greatly assists the spreading of the flames. When a fire is discovered before it has gained possession of the stairs, its suppression is comparatively easy; but the staircase once on fire, there is but slight chance of saving the building.

Effectually to prevent the spread of fire, therefore, it is absolutely necessary that the stairs should be wholly composed of some incombustible substance. In many places on the continent the stairs are always of stone, which is quite sufficient to account for the speedy manner in which conflagrations are extinguished by the fire associations of those countries, where, although the number of fires are considerable, the amount of damage is usually very small. Nothing gives a more elegant appearance to a house than a clean well-proportioned stone staircase, and this material is by far the most eligible for the purpose; economy, however, may dictate the employment of a cheaper material without prejudice to the effect. In ordinary dwelling houses it is necessary that the roof should be as fight as practicable, nor is it very essential to bestow fire-proof qualities on this part; but in manufactories and public edifices it becomes desirable to render the building fire-proof throughout. This is done in some cases by using cast-iron framed roofs, with metallic or other covering. At the New Palace, in St. James's-park, the builder, Mr. John Richardson, of Spencer-street, introduced fire-proof floors and roofs, composed of hollow earthen coombs or pots, invented some thirty years before, and first used at Knight's Hill, near Dulwich, the seat of Lord Thurlow. The coombs are arranged in arches, springing from stone abutments resting on the flanges of the iron girders; the spandrils of the arches are filled up with brick work, forming a level roof, which is covered with hot cement. This cement is composed of chalk, coal tar, and sand. The first coat being levelled with heated irons, is suffered to harden; a second coat is then applied, and the slates embedded in the cement while it is hot Woeful experience has shown that the defective construction of chimneys and setting of stoves have been a fruitful source of fires; a slight attention to these points would be sufficient to remedy the evils arising from this cause. Lateral openings are sometimes imprudently suffered to remain, communicating between the chimney and sides of the room; these places in time become filled with soot, which a falling spark ignites, and sets fire to the apartment. No beam should on any account be permitted to enter a chimney; this was too common formerly, and has caused the destruction of many buildings.

An act of parliament, passed some years back, for regulating buildings, and so preventing the spread of fires, has tended in some degree to remedy the evils just referred to; this act, however, contains many incongruities, and it stands greatly in need of that revision which it is expected very soon to undergo. It would doubtless be both useful and interesting to follow out the subject of fire prevention, and detail the cautions necessary to be observed in the application of fire-heat to manufacturing processes, as well as the management of fire and light in the arrangements of domestic economy. The limits of this work, however, will not permit us to extend the present article; but in many of those that follow we shall have occasion to make some observations on the subject.