Protection from Fire and Thieves / Including the construction of locks, safes, strong-rooms, and fireproof buildings; burglary, and the means of preventing it; fire, its detection, prevention, and extinction; etc.

by George Hayter Chubb

‘I then set it on end in an open yard exactly as it had stood in the warehouse, with the pedestal underneath, the cap above, and the beam across the cap; placed more than a ton of shavings, light wood and heavy wood, round it, and after saturating the whole heap with petroleum applied a light to it. After this I kept men pumping petroleum on it until my stock was exhausted. At the end of 2½ hours I withdrew the post, beam, and other parts from the fire, and within a few minutes from the time they were withdrawn they ceased to burn.

‘I then sawed off, horizontally, a few feet of that part which had suffered most from the flames, and afterwards split the same piece longitudinally with steel wedges, in order to examine its condition.

‘The post was of pitch-pine, about the most inflammable wood I know, and yet after exposure to fire for seven hours, the fury of which could not be exceeded except in blast-furnaces, it contained, and still contains within it, a quantity of uninjured and apparently fresh wood, probably capable at this moment of supporting the whole weight which the original post may have been designed to carry.

‘Immediately after the saw-cut, and again after the cleaving with steel wedges, I carefully examined the centre, and found it just perceptibly warm to the touch, but nothing more, thus proving that the fibre, in which the strength lies, must have been quite uninjured.

‘The lessons to be drawn from this I take to be as follows: A massive storey-post of even the most inflammable wood is absolutely and perfectly proof against any heat that can be applied to it—will not of itself burn at all, but requires a continual supply of highly inflammable substance to keep it burning, and when the supply is withdrawn ceases to burn; and lastly, after being exposed to flames for seven hours of very great intensity, is not injured to a greater depth than about two inches from the original outer surface, and still shows a centre as clean and fresh as when it was first put in.

‘There may be other materials suitable for this purpose which are capable of resisting the effects of heat, and, if so, I hope we may one day hear of them; but, in the meanwhile, I venture to submit what I consider to be strong practical testimony in favour of massive timber for the internal supports of heavily-loaded buildings. Oak or elm is the best wood to use, and will defy destruction for hours.’

Messrs. Dennett, whose name is better known in connection with the Dennett Arch, have introduced a new mode of covering up iron columns in such a manner that they stand through intense heat, and have the advantage of being small in bulk. The accompanying engraving will make the following explanation clear.

Strips of corrugated hoop-iron are fastened at intervals by wire close to the iron column, and all is then encased with concrete 3½ inches in thickness, made as described on page 86. An experiment was tried at Nottingham with one of these columns placed in a fire of wood and shavings saturated with gas-tar, and allowed to burn with a fierce heat for a space of 4½ hours. When half the time had elapsed the column was thrown over, so as to lie horizontally in the fire, and have its whole length exposed to the flames. The fire was at length extinguished by water being thrown on, in order to make the test still more severe, but on examination the concrete casing had not cracked or broken in any part, while the column underneath, as soon as a portion of its covering could be removed, was cool enough to be handled with impunity. It will be interesting to note the development of this invention; for in the event of farther tests in actual practice being as satisfactory as that already named, it is likely to come into very prominent use.

The careless way in which chimneys are built is the cause of frequent danger. By communicating with each other in the same gable, fire will often spread and wrap the whole house in flames. One of the principal streets in Edinburgh had scarcely a chimney-head that was not in this condition. The ends of joists or pieces of timber are sometimes allowed to protrude into chimneys, and then it is generally by accident if the building does not catch fire.