In a range of stores, the different warehouses to be divided by strong partition-walls, in no case less than eighteen inches thick, and no more openings to be made than are absolutely necessary for the admission of goods and light. That the iron columns, beams, and brick arches be of strength sufficient, not only to support a continuous dead pressure, but to resist the force of impact to which they are subject by the falling of heavy goods upon the floors. That in order to prevent accident from the columns being melted by intense heat in the event of fire in any of the rooms, a current of cold air should be introduced into the hollow of the columns, from an arched tunnel under the floors. There is no doubt that if the second principle could be carried out, namely, the total exclusion of air, the fire would go out of itself; but it seems, to say the least of it, very doubtful indeed if this can be accomplished, and if it could, the carelessness of a porter leaving open one of the doors or windows, would make the whole useless. The fifth principle shows that Mr. Fairbairn has omitted to allow for the loss of strength the iron may sustain from the increase of temperature. The last principle would not be likely to answer its purpose, even if it was possible to keep these tunnels and hollow columns clear for a number of years, which is scarcely to be expected. A piece of cast-iron pipe, one-and-a-half inch in diameter, was heated for four minutes in a common forge, both ends being carefully kept open to the atmosphere, when, on one end being fixed in a vice, and the other pulled aside by the hand, it gave way. One of the principal objections to the kind of fire-proof buildings above described, is, that absolute perfection in their construction is indispensable to their safety; whereas buildings of a more common description are comparatively safe, although there may be some errors or omissions in their construction. Indeed, Mr. Fairbairn states in the same Report, that "it is true that negligence of construction on the one hand, and want of care in management on the other, might entail risk and loss to an enormous extent." The following is a very clear proof of the inability of cast iron to resist the effects of fire:--