It is commonly imagined that the introduction of hot water, hot air, and steam pipes, as a means of heating buildings, cuts off one 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 will suffice to ignite. The circular rim supporting a still at the Apothecaries' Hall, which was used in the preparation of some medicament that required a temperature of 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. Braidwood, in his evidence before a Committee of the House of Lords in 1846, stated that it was his belief that by long exposure to heat, not much exceeding that of boiling, water, or 212°, timber is brought into such a condition that it will fire without the application of a light. The time during which this process of desiccation goes on, until it ends in spontaneous combustion, is, he thinks, from eight to ten years--_so that a fire might be hatching in a man's premises during the whole of his lease without making any sign!_ Under the heads "Incendiarism," "Doubtful," and "Unknown," are included all the cases of wilful firing. The return Incendiarism is never made unless there has been a conviction, which rarely takes place, as the offices are only anxious to protect themselves against fraud, and do not like the trouble or bad odor of being prosecutors on public grounds. If the evidence of wilful firing, however, is conclusive, the insured, when he applies for his money, is significantly informed by the secretary, that unless he leaves the office, _he will hang him_. Though arson is no longer punished by death, the hint is usually taken. Now and then such flagrant offenders are met with, that the office can not avoid pursuing them with the utmost rigor of the law. Such, in 1851, was the case of a "respectable" solicitor, living in Lime Street, Watling Street, who had insured his house and furniture for a sum much larger than they were worth. The means he adopted for the commission of his crime without discovery were apparently sure; but it was the very pains he took to accomplish his end which led to his detection. He had special]y made to order a deep tray of iron, in the centre of which was placed a socket, the tray he filled with naphtha, and in the socket he put a candle, the light of which was shaded by a funnel. The candle was one of the kind which he used for his gig-lamp, for he kept a gig, and was calculated to last a stated time before it reached the naphtha. He furtively deposited the whole machine in the cellar, within eight inches of the wooden floor, in a place constructed to conceal it. The attorney went out, and on coming back again found, as he expected, that his house was on fire. Unfortunately, however, for