OF THE FRANKLIN INSTITUTE, OF THE State of Pennsylvania, FOR THE PROMOTION OF THE MECHANIC ARTS. DEVOTED TO MECHANICAL AND PHYSICAL SCIENCE, CIVIL ENGINEERING, THE ARTS Reporter of American Patents, C. M. KELLER, late Examiner, Patent Office, Washington. THIRD SERIES. VOL. XVII. WHOLE NO. VOL. XLVII. PHILADELPHIA: PUBLISHED BY THE FRANKLIN INSTITUTE, AT THEIR HALL. 1849 Wrought Iron Bowstring Girders for Bridges. The following diagram represents a wrought iron rib, or girder, now being employed in the construction of bridges, of 120 feet and 130 feet span, at Messrs. Fox, Henderson & Co.'s establishment, the London Works, near Birmingham, under the superintendence of Mr. Jos. Locke, C. E., M. P. On the 6th instant, one of them was publicly tested at the works, in the presence of a number of scientific gentlemen and engineers. 120 ft. The bridge rib had been erected, ready for proof, in an open space in front of the London Works, and presented a clear span of 120 feet between the bearings. It is constructed entirely of wrought iron, and consists of an arch of boiler plates and angle iron, tied across at the ends by horizontal bars, and the tie bars are connected with the arch by vertical standards, and by a double system of diagonals, which have the effect of distributing over the whole curve of the arch, the action of weights placed on, or passing over, any point of the bridge. The proof was applied by loading VOL. XVII.—THIRD SERIES.-No. 1.—January, 1849. |