brick-arch system, yet it is rather to bring fire-proof construction within the reach of every one, than to offer it in opposition to other systems, or methods, that the present plan has been introduced. Hitherto fire-proof construction has seldom been thought of for general purposes; it has been generally considered that, however desirable, it was too costly for its use to be entertained; a difficulty for which a remedy has certainly now been provided, and one the value of which is not merely theoretical, but has been practically demonstrated for many years. Of the value and importance of iron as a material for construction, perhaps too much could scarcely be said, and its comparatively limited use may probably be owing, in some degree, to the mistrust entertained as to its strength and capabilities. Objections are entertained to the use of cast iron; but however well founded these may be, they are removed by the introduction of wrought iron, in the form of joists and girders for building purposes. With the latter material it may be truly said, that every imaginable difficulty is met; and it is not one of the least recommendations of the system, that its general adoption would greatly extend the use of a material, the whole of the cost of the production of which is spent in employing home labour, and one, also, which contributes so much to the greatness of this country. The paper is illustrated by a series of diagrams, from which the woodcuts (Figs. 1 to 9, presented by the Author,) have been compiled. APPENDIX. ESTIMATES OF COST, BASED ON LONDON PRICES. APPROXIMATE COST OF FLOORS FOR DWELLING-HOUSES. Room 18 feet long by 16 feet wide. Timber floor, of the commonest description : 16 joists, 17 ft. 6 in. long, 10 in. x 2 in. = £. s. d. Per square. 6 17 5 0 5 0 Fire-proof floor with 1-inch flooring boards, 23s. extra. ESTIMATED COST OF THE FLOOR OF A MILL, OR FACTORY, Constructed with Timber Girders, Joists, and Flooring, viz. : Main girder, 65 ft. 12 in. x 10 in. = 54 cubic ft., at 2s. 6d. £. s. d. Per square 50 joists, 29 ft. 11 in. x 3 in. 332 cubic ft., 196 yards lath-and-plaster ceiling, at 1s. 2d. 11 8 Constructed fire-proof, with Girders and Joists of Constructed fire-proof, with Cast-iron Girders and 12 cast girders, 15 ft. 2 in. long, = 7 tons, at 67.10 0 0 6 1 6 39 50 9 0 3 13 6 Mr. BRAIDWOOD, in answer to questions from the President, said the system described appeared to be a decided improvement on that of brick arches and iron girders, with timber floors. He objected to iron columns in warehouses: in case of fire, the draught of air and flame either speedily melted them, or so heated them, that they crumbled beneath the superincumbent mass, or else they were split by the water from the engines falling upon them. Under any circumstances they were fertile sources of danger to the firemen, as it was not possible to calculate upon the time they might resist the fire; whereas good solid timber posts endured for a long time, and the men being able to reckon something like their term of duration, felt more confidence in going into the blazing building. The water thrown on a timber support, if it had any effect at all, did good; whereas it generally accelerated the destruction of iron, or stone columns. The great objection to wood floors, in dwelling-houses, was the facility they afforded for the fire travelling between them and the ceilings: this was obviated by Mr. Barrett's system, and it would thus tend to a greater amount of security, if it was more generally adopted. The number of detached rooms in dwellinghouses was always in their favour, especially if the floors were 'pugged.' Warehouses should, for safety from fire, be always divided into numerous compartments, communicating only through double wrought-iron doors. Lieutenant JACKSON, R. N., suggested the use of Sir W. Burnett's system of saturating timber with chloride of zinc, which had the effect of rendering even fine fabrics of linen, or of lace, uninflammable. If this was adopted for the supports and floors of warehouses, their duration as well as resistance to flame would, at any rate, be increased at a trifling expense. The coverings of the steam boilers in H. M. Navy were ordered to be so prepared. Mr. C. MAY did not think that any preparation would enable timber to resist, permanently, the action of flame, although the duration of the wood might be increased, which would be to some extent advantageous. In all the extensive fires he had seen, the iron columns appeared to have been melted with extraordinary |