braces in every possible way to strengthen the rickety concern. I don't believe it was possible that we should not have had an awful disaster if it had not been for my Boston friend, nor do I believe it was, though it managed to hold us, half as strong as it should have been, for no building should be erected to sustain great numbers of people which cannot bear up twice the number it can be made to hold. Just preventing a thousand persons from being crushed to death is not enough, when the author of this book is to be one of them.

As buildings grow old, those which were strong enough to bear all the people they could contain when new, will become each season more unsafe. The number of people occupying them increases; and in times of excitement the buildings may become overloaded, and then another sensational disaster will go flying over the telegraph lines.

CHAPTER VIII.

SPONTANEOUS IGNITION AND INCENDIARY FIRES.

I PROPOSE in this chapter not only to speak of fires which properly come under these heads, but also of those which from their singularity or the peculiar lesson they may teach, it may be well to place in a book of this kind. In 1846, Mr. Braidwood was before a committee of the House of Lords, and said: "It is my belief that by long exposure to heat, not much exceeding that of boiling water at 212°, timber is brought into such a condition that it will take fire without the application of a light. The time during which this process goes on until it ends in spontaneous combustion, is from eight to ten years; so that a fire might be hatching in a man's premises during the whole time of his lease without making any sign!" Now the person whose house is burned up, will say to the insurer, and to the community: "It was not the furnace, the stove, or the steam-pipes, that set the fire; and he will call the carpenter, the mason, and the other mechanics, who will agree with him that it was impossible for fire to take from any such

cause.

Then the common people, who like to believe in anything mysterious, believe that there was something strange about the fire which will never be explained. The explanation of such fires I propose to give, and to do it in the most simple manner, avoiding all words which might mislead even those who have acquired only the most common education.

It is commonly imagined that the introduction of hot water, hot air, and steam-pipes as a means of heating buildings cuts off an avenue of danger from fire. This is an error. Iron pipes, often heated up to 400°, are placed in close contact with floors and skirting boards, supported by slight diagonal props of wood, which a much lower degree of heat would suffice to ignite. The circular rim at Apothecaries Hall which was used in the preparation of some medicament that required a temperature of only 300°, was found not long ago to have charred a circle at least a quarter of an inch deep in the wood beneath it in less than six months. Mr. Hosking, the author of the "Guide to the Proper Regulation of Building in Towns," says:

66

DAY AND MARTIN'S.

'Day and Martin's blacking manufactory was heated by means of hot water through iron tubes. In December, 1848, the wooden casing, etc., was

DANGER FROM DRIED WOOD.

123

found to be on fire. The only cause to be discovered was the exposure for a long time of the wood to the heated pipes."

The pipes were not in contact with the wooden casing, but they were stayed and kept upright by cross fillets of wood which touched them, and these it was which appeared to have taken fire. In every case where the prop which held the pipe from the floor had been displaced, the boards were charred.

DANGER FROM DRIED WOOD.

"Wood dried in the thorough manner we have mentioned is so liable to catch fire from flame that practical men imagine there must be some kind of atmosphere surrounding it of a highly imflammable nature. A stick of pine-wood thrust into a fire will emit from its free end a volatile spirit of turpentine, which lights like a jet of gas." That this vapor has been the cause of many fires I have no doubt. Fires in drying-houses often occur, and the reason has not been found. How easy it would be for a little cloud of such vapor to float off to a light, or to the furnace, to be lighted, and to return to the dried wood a living flame, which would, in five minutes, set the whole building in a blaze. Many other buildings than dry-houses have, I think, been fired in that manner.

DANGER FROM VAPOR.

That a vapor rises from inflammable oils is well understood; but there are, as we have seen in wood, doubtless others, arising from many things heated for drying or for some other purposes. In 1866 we are told of a fire in a wool-drying room: "He entered the room with his lantern. Soon after leaving he smelt smoke, and opening the wooldrying room, he found it full of smoke. As soon

as the air was admitted the fire flashed all over the room at once, as by flashes of lightning." In 1868 a similar fire occurred in a room for drying wool: "The watchman entered it with his lantern. Leaving it for a moment, he wished to return, but found it full of fire, and was obliged to escape by a window."

SPONTANEOUS COMBUSTION IS AT PRESENT VERY LITTLE UNDERSTOOD.

The London "Quarterly" for January, 1855, says: "The cause of most fires from this source is lost in the consequence." That is, the engines arrive so late that the signs of the cause are burned up. "A porter swept the sawdust from the floor into a heap, upon which the oil (olive) from a broken flask dripped. The sun shone on the heap, and in sixteen hours it took fire."