Page:Architectural Review and American Builders' Journal, Volume 1, 1869.djvu/86

 m Sloan's Architectural Revieio and Builders' Journal. [July, to level the surface preparatory for the reception of the floors, this will be found a floor of exceedingly light construction, perfectly fire-proof, and containing all the elements of strength and rigidity which can possibly be attained by iron beams with brick arches, and I conceive that the time is not far distant when wro ught-iron beams and wrought-iron places will form the principal supports of the floors of fire-proof buildings." Report from the Franklin Institute of Pennsylvania. Hall of the Franklin Institute, Philadelphia, Feb. 26, 1868. The Committee on Science and the Arts, consti- tuted by the Franklin Institute of the State of Pennsylvania, for the promotion of the Mechanic Arts, to whom was referred for examination a Fire-Proof Ceiling invintecl by Mr. Joseph Gilbert, of Philadelphia, Penn., REPORT, That the nature of the invention is in the use - of corrugated sheet iron, supported upon, and spanning the space between iron beams, the corrugations being so arranged that a series of alter- nate convex and concave arches extend as ribs and depressions across the space between the beams, thus giving to the sheets vertical stiffness. The sheets are covered with cement, which increases this stiffness and prevents moisture from penetrating downwards to the iron. The sheets may extend straight from beam to beam, or may be arched as is custo- mary with brick or concrete fire-proof floors. When used as flooring it is arched so that the top of its cement cover is nearly flush with that of the beams. Any de- scription of floor may be laid on the beams. The intervening space between floor and arch may be filled with con- crete, resting against haunches of brick placed next the sides of the beams. The corrugated sheets are secured to the beams (acting thus as ties or braces) by means of cast-iron ledges of suitable shape, resting upon the lower flanges of the beams, and fastened thereto. It will be evident from this description that the distinguishing feature of the mode under discussion, as compared with other plans of fire-proof floors, is in the substitution of corrugated sheet- iron, covered with cement for either brick or concrete arches, or for flat sheets of iron covered with cement. The following advantages appear to be secured by it : 1st. A considerable reduction in the weight of the floor, which enables the beams to be lighter, and which, from both these causes, reduces the weight to be borne by the walls of the building. 2d. A saving of time in the execution of the work, and in scaffolding for completion of the building, as each story may be separately progressing without fear of accident, while the walls are laterally strengthened during the course of building. 3d. Some saving in story height may be effected, owing to the reduced thick- ness of the arch, without increasing the number of beams employed. So far as regards its fire-proof qual- ities, the Committee believe it to be fully equal to either of the modes commonly employed. Possessing the advantages already enumerated, its introduction in lieu of other systems will, in the opinion of the Committee, be governed by com- mercial considerations, into which they cannot of course enter. There does not appear to be any good reason why its expense should be greater -than brick arches on iron beams. By order of the Committee. WM. HAMILTON, Actuary. Messrs. J. Vaugiian Merrick, Thos. S. Stewart, Edwin F. Durang, Committee of Examination. The following Philadelphia architects have fully indorsed the foregoing Report