TUBULAR AND OTHER IRON GIRDER BRIDGES, PARTICULARLY DESCRIBING THE BRITANNIA AND CONWAY TUBULAR With a Sketch of Iron Bridges, AND ILLUSTRATIONS OF THE APPLICATION OF MALLEABLE IRON BY G. DRYSDALE DEMPSEY, C.E., VIRTUE BROTHERS AND CO., 1, AMEN CORNER, PATERNOSTER ROW. CONTENTS. Sketch of the History of Iron Bridges-Cast-Iron Arched Bridges Page Malleable Iron-its Manufacture into Plates and Bars of different Sections The application of Iron ilates in the formation of First Constructions of Wrought-Iron Plate Girders-Mr. Fair- bairn's Patent Wrought-Iron Tubular Girders-Their applica- tion to Bridges-building-Bridge on the line of the Blackburn and Bolton Railway-Bridges of the Liverpool Landing Stage -Great Bridge erected by Messrs. Fairbairn and Sons, on the line of the Manchester, Sheffield and Lincolnshire Railway at Malleable-Iron Bridges of different Constructions-Lattice Bridges -Tubular Bow-Bridge-Tubular Girder Bridge, with inter- vening Arches of Brick-work-Compound Wrought-Iron and Page Mawr--Parliamentary Proceedings, and Engineers' Reports upon the Communication between London and Dublin-Iron Bridges proposed by Mr. Rennie in 1802-Mr. Robert Stephenson's Design for Cast-Iron Arched Bridges, and selection of Site over the Britannia Rock-Admiralty Opposition, and Mr. Stephenson's General Principles which distinguish Girder Bridges from Arched Bridges Mr. Fairbairn's Experiments and Report on Tubular Description of the BRITANNIA BRIDGE-The Masonry-Britannia Tower-Anglesea and Carnarvon Towers and Abutments- Arrangements for constructing the Tubes-Main Tubes and Land Tubes-Description of their Construction-Scaffolding and Staging-Arrangements for floating the Tubes-The Pontoons INTRODUCTION. ENGINEERING Works being usually of a public character, naturally excite a general interest throughout the community, the extent of which feeling is commonly commensurate with the novelty, the magnitude, and the utility of the performance. Thus, a railway, a harbour, a lighthouse, a dock, or a bridge, regarded as subservient to public convenience, is watched with public anxiety, and its completion becomes an occasion of public gratulation. Such a work is therefore a peculiarly suitable subject for one of a series of Rudimentary Volumes, dedicated, in their several features of style, size, and price, to the use of a largely-extended circle of readers and students. And it must be admitted by all that the works which form the main subjects of the following pages have claims of nearly unprecedented amount upon our attention, being new, great, and useful in a pre-eminent degree. The application of wrought iron to the purpose of bridgebuilding truly constitutes a new branch of the art, and is, as already proved, susceptible of modifications of form and construction, far more efficient than those of the cast metal. A perfectly horizontal and rigid roadway or railway, 460 feet in length, and having only 3 feet of depth below it, could not be obtained by any other known arrangement of parts than that herein illustrated; and with these successful examples before us, the task of future designing is facilitated to an incalculable extent. For smaller spans the depth of construction may be still further reduced, as shown in the splendid bridge over the Trent, described in this volume; and for the particulars of which we take the pleasure of expressing our obligation to Messrs. Fairbairn and Sons, who have also |