These accidents may in a great measure be avoided by constant care and attention to cleanliness, and where paints and oils are necessary, by keeping them in some place outside the principal buildings. Dust-bins should, as much as possible, be placed in the open air, and where that cannot be done, they should be emptied once a day. No collection of rubbish or lumber of any sort should be allowed to be made in any building of value. Mr. Wyatt Papworth, architect, has published some very interesting notes on spontaneous ignition, giving several well-authenticated instances. _Incendiarism_ may be divided into three sorts--malicious, fraudulent, and monomaniac. Of the former there has been very little in London for many years. The second, however, is rather prevalent. The insurance offices, which are the victims, protect themselves as well as they can, but an inquest on each fire is the true mode of lessening the evil. This is much more the interest of the public than at first seems to be the case. In several instances where the criminals were brought to punishment by Mr. Payne's inquests, people were asleep in the upper parts of the houses set fire to, and in one case there were as many as twelve or fifteen persons. This, however, is seldom stated in the indictment, as, if it is, the punishment is still death by the law, and it is supposed that a conviction is more easily obtained, by the capital charge being waived. Monomania is a rare cause of incendiarism, but still several well-certified cases have occurred in which no possible motive could be given. In one instance a youth of fifteen set fire to his father's premises seven times within a few hours. In another, a young female on a visit set fire to her friend's furniture, &c., ten or eleven times in the course of one or two days. In neither case could anything like disagreement or harshness be elicited, but the reverse. In other instances, it has been strongly suspected that this disease was the cause of repeated fires, but there was no positive proof. In all these cases, known or suspected, the parties were generally from fourteen to twenty years of age. FIRE-PROOF STRUCTURES.