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. FOOTNOTES: [Footnote A: _Vide_ Seventh Report of the British Association, 1837, vol. vi. page 409.] [Footnote B: _Vide_ Report on the Fall of the Cotton Mill, at Oldham, and part of the Prison at Northleach, page 4. Folio. London: Clowes and Sons, 1845.] [Footnote C: _Vide_ Report of W. Fairbairn, Esq., on the Construction of Fire-proof Buildings. With introductory Remarks by Samuel Holme, page 11, _et seq._ Tract, 8vo. Liverpool: T. Baines, 1844.] [Footnote D: The Author has been informed by Mr. Farey, M. Inst. C.E., that a fire took place, in 1827, in a mill belonging to Mr. Marshall, of Leeds, the whole of which, with the exception of the roof, was fire-proof. The upper floor was filled with flax, which took fire; the roof fell in, and the heat so affected the iron beams of the floor, as to cause them to give way.]