FIRES, PREVENTION or. Among the various modes which have from time to time been proposed for this purpose, the most useful and important are those relating to the manner in which buildings are constructed. The general prin ciples to be attended to are simple and briefly stated, viz. the use of incom bustible materials to the greatest possible extent, and the placing of those necessarily inflammable in situations and under circumstances the most unfavourable for combustion. The incombustible materials commonly employed in building are stone, brick, and metal ; the combustible is timber, in all its various forms. Many ingenious expedients have been resorted to for the purpose of rendering wood fire-proof; solutions of muriate of ammonia, muriate of soda, sal ammoniac, borax, alum, and several other salts and alkalies, have this property to a certain extent. Professor Fuchs, member of the Academy of Science at Munich, invented a composition for making wood fireproof, which consisted of ten parts potass or soda, fifteen parts fine silicious earth, and one part charcoal, mixed together with water. This composition, applied to the surface of wood, forms a vitreous coat, which effectually resists the action of fire. After some decisive experiments had fully established the efficacy of this plan, the Royal Theatre at Munich was protected by the application of this composition ; the surface covered was upwards of four hundred thousand square feet, and the expense, it is said, did not exceed five thousand francs. The following is an English composition for the like purpose :—one part, by measure, of fine sand, two parts wood ashes, and three parts slacked lime, ground together in oil, and laid on with a painter's brush, the first coat thin, the second thick. This forms a very strong and adhesive coating, which is both fire and water-proof. There are, in general, however, many practical objections to the use of these preventives ; and the more feasible method of obtaining the desired security appears to be in the judicious selection and skilful disposition of the materials most commonly employed. Bricks form the staple material for building in most of the towns in this country, and with them the external walls are usually constructed ; where due attention is paid to the prevention of fire, the partitions will be of the same material. If circumstances permit it, brick arches will also be used for supports. When it is desirable, for the purposes of trade, &c. to support the walls on brestsummers, those of cast iron are employed. Pillars of the same material are also frequently used with advantage to support fronts of considerable length. In this way the skeleton or frame-work of a building is easily completed in a fire-proof manner. The
next thing, then, to be attended to, is the floor ; and here we find caution extremely necessary, as the security of the building depends greatly upon the manner in which the floors are constructed. In dwelling houses, floors of wood are essential to an Englishman's notion of comfort; nor is there any real difficulty in obtaining them of this material perfectly compatible with the end now under consideration. There is a particular description of floor occasionally used in Edinburgh, which, although not absolutely fireproof, is certainly almost practically so. It is composed simply of plank, two and a half or three inches thick, so closely joined and so nicely fitted to each other and to the walls, as to be completely air tight. Its thickness, and its property of being air tight, will readily be observed to be its only cause of safety. A floor of a somewhat similar kind has been employed in the neighbourhood of Manchester with success ; the planks are about three inches thick, jointed and ploughed on the edges for the purpose of receiving slips of iron called tongues, that enter some distance into each board ; this makes a tight and substantial floor, which, as well as the former, should be laid on iron joists. Great protection is capable of being given to boarded floors, by using a strong fire-proof cement for the ceilings; the plaster at present employed is so to a certain extent, but this may be greatly improved. If a fire occurred in a room protected in this manner, the chance is more than ten to one that it would burn itself out before it could ignite the building. It would be very difficult to set fire to the floor, from the natural tendency of flame and heat to ascend ; it would be still more difficult to ignite the ceiling, from the resistance offered to the flames by cement, iron joists, and, finally, by the closeness of the flooring. If the fire should not, however, be entirely repulsed, still its progress would be so greatly retarded as to afford plenty of time for the successful application of the usual modes of suppression. Before quitting this subject, however, there are some kinds of floors veritably fire-proof, which' could not with propriety be omitted. At Manchester, fire-proof floors have been constructed in the following manner :—the columns and beams are of cast iron, and are firmly secured in their places with wrought-iron bars that traverse from beam to beam. Upon a margin underside the beam spring arches of brick work ; these are filled to a level on their upper side with hard rubbish, and then covered with flags or tiles.