Fire prevention and fire extinction

by James Braidwood

In this case it mattered little whether the pillars stood or fell, but it would be very different with some of the large wholesale warehouses in the City, where numbers of young men sleep in the upper floors; in several of those warehouses the cast-iron pillars are much less in proportion to the weight to be carried than those referred to, and would be completely in the draught of a fire. If a fire should unfortunately take place under such circumstances, the loss of human life might be very great, as the chance of fifty, eighty, or one hundred people escaping in the confusion of a sudden night alarm, by one or two ladders, to the roof, could scarcely be calculated on, and the time such escape must necessarily occupy, independent of all chance of accidents, would be considerable.

For the reasons here stated, I submit that large buildings, containing considerable quantities of combustible goods, with floors of brick-arches, supported by cast-iron beams and columns, are not, practically speaking, fire-proof; and that the only construction which would render large buildings fire-proof; where considerable quantities of combustible goods are deposited, would be groined brick-arches, supported by pillars of the same material, laid in proper cement. I am fully convinced, from a lengthened experience, that the intensity of a fire,—the risk of its ravages extending to adjoining premises, and also the difficulty of extinguishing it, depend, cæteris paribus, on the cubic contents of the building which takes fire, and it appears to me that the amount of loss would be very much reduced, if, instead of building immense warehouses, which give the fire a fortified position, warehouses were made of a moderate size, with access on two sides at least, completely separated from each other by party-walls, and protected by iron-doors and window-shutters. In the latter case, the probability is, that not more than one warehouse would be lost at a time, and perhaps that one would be only partially injured.

It is sincerely to be hoped that the clause in the last Metropolitan Building Act, restricting the size of warehouses, may be more successful than its predecessor, for it is not only property that is at stake, but human life. In many of these "Manchester warehouses," there are fifty or one hundred and upwards of warehousemen and servants sleeping in the upper floors, whose escape, in case of fire, would be very doubtful, to say the least of it.[E]

Covering timber with sheet-iron is very often resorted to as a protection against fire. I have never found it succeed; but Dr. Faraday, Professor Brande, Dr. D. B. Reid, and Mr. W. Tite, M.P., are of opinion that it may be useful against a sudden burst of flame, but that it is worse than useless against a continued heat.

In wadding manufactories the drying-rooms were frequently lined with iron-plates, and when a fire arose there, the part covered with iron was generally found more damaged than the rest; the heat got through the sheet-iron, and burnt the materials behind it, and there was no means of touching them with water until the iron was torn down; sheet iron should not, therefore, be used for protecting wood.

Even cast iron, one inch thick, laid on tiles and cement three inches thick, has allowed fire to pass through both, to the boarding and joisting below, merely from the fire in an open fire-place being taken off and laid on the hearth. This arises from iron being so good a conductor that, when heat is applied to it, it becomes in a very short time nearly as hot on the one side as the other. If the smoke escapes up a chimney, or in any other way, there may be a serious amount of fire before it is noticed.

In a fire at the Bank of England, the hearth on which the stove was placed was cast iron an inch thick, with two-and-a-half inches of concrete underneath it; but the timber below that was fired.

With regard to the subject of fire-proof dwelling-houses of average size, I consider that such houses when built of brick or stone, with party-walls carried through the roof; the partitions of brick, the stairs of slate or stone, the joists of wrought iron filled in with concrete, and the whole well plastered, are practically fire-proof because, as stated at the opening of this chapter, there is no probability that the furniture and flooring in any one room would make fire enough to communicate to another. The safest manner of heating such houses is with open fire-places, the hearths not being laid upon timber. Stone staircases, when much heated, will fracture from cold water coming suddenly in contact with them; but in a dwelling-house built as described above, there is very little chance of such a circumstance endangering human life, even with wooden steps carried upon brick walls, and rendered incombustible by a ceiling of an inch and a quarter of good hair mortar and well pugged, all the purposes of safety to human life would be attained.

There is a particular description of floor, which, although not altogether fire-proof, is certainly (at least so far as I can judge), almost practically so for dwelling-houses. It is composed simply of plank two and a-half or three inches thick, so closely joined, and so nicely fitted to the walls, as to be completely air-tight. Its thickness and its property of being air-tight, will be easily observed to be its only causes of safety. Although the apartment be on fire, yet the time required to burn through the floor above or below, will be so great, that the property may be removed from the other floors, or, more probably, if the means of extinguishing fire be at hand, it may be subdued before it can spread to any other apartment. The doors must of course be made in proportion, and the partitions of brick or stone.

Before closing the subject of fire-proof structures, I will add a few words upon fire-proof safes. These are all constructed with double casings of wrought iron, the interstices being in some filled with non-combustible substances, such as pumice stone and Stourbridge clay, and in others with metal tubes, that melt at a low temperature, and allow a liquid contained in them to escape, and form steam round the box, with the intention of preventing the heat from injuring the contents. Such safes I have never found destroyed; and in some cases, after large fires, the whole of the contents have been found uninjured, while the papers in common safes, merely made strong enough to prevent their being broken into, were generally found consumed.