The Works Of Messrs. Schneider And Co.

THE CHANNEL BRIDGE; IRON BUILDINGS. 151 cantilever trusses eacb of 187.500 metres (615 ft.), on the ends of which are fitted smaller central girders 125 metres (410 ft.) long. The 400-metre (1,312-ft.) spåns are formed by the joining together of two large trusses, thus balancing the overliang of the 500-metre (1,640-ft.) spåns. The joint is of a special kind, which allows for expansion while it maintains both. ends level. The arrangements which support the girders on the pillars are fixed. The main girders are on the Warren type; their maximum height at the parts over the pillars is 63.150 metres (207 ft.); they are 38 metres (124 ft.) high at the centre of the 400-metre spån, and 11 metres (36 ft.) at both ends of the small 125-metre central sirder. The two main girders are made slanting one towards the other ; the cross-section of the work is, therefore, trapézoïdal. The distance from centre to centre of the been considered with the greatest care, and the plant of Messrs. Schneider and Co.’s Chalon Works is adaptecf for its rapid construction. It is estimated that seven years would be required for completing this huge work. Iron Buildings.—As has been shown in the history of the Chalon Works, the progress réalisée! by Messrs. Schneider and Co. in the construction of iron buildings has always been on a par with that realised by them in bridge construction. The firm have made a speciality of constructions for works and factories, and they were the first to build large-span halls, such as the Orleans Railway Station in Paris, the Machinery Hall for the Paris Exhibition of 1878, the Santiago (Chili) Railway Station, &c. It is not necessary to enter into too many details with regard to these constructions, as they are well known and have often been described. It will be sufficient to give Fig. 503. Design for the Channel Bridge. lower frames over the pillars is 25 metres (82 ft.) ; the top fraines are 5 metres (16 ft.) apart. The two main girders are United together by lower horizontal stays, and by a series of transverse stays in the same plane as that of the trellis-bars that withstand compression strains. The superstructure is designet! for two railway lines, and is placed on transverse girders made of Warren three- link beams, which carry four rows of string-pieces made of trellis girders of varions heights, firmly fixed and stayed together. The outside rows of string-pieces are fitted with brackets to which are fixed screen railings 3 metres (9 ft. 10 in.) high, and which serve to reduce the action of the wind on the trains. Other screens, arranged to intercept the wind, are fitted to the main ribs of the girders ; these have enabled the realisation of an important sa ving on the total weight of metal. Such are the principal data of the Channel Bridge. All the details concerning the construction and érection have | general data concerning those buildings which may be considered as types. i. The Paris Railway Station of the Orleans Railway Company (1869).—The principal characteristics of this type of construction are lightness and perfect perspective of the trusses, the two combining to form a building in which ventilation and lighting are fully insured. Previous to the construction of trusses without ties, the Polonceau trusses were those which best fulfilled all the conditions required, and this form was adopted by Messrs. Schneider and Co. in the construction of the main gallery of this railway station. The execution of these trusses was a bold under- taking for the time ; they are 52 metres (170 ft.) in spån, the ridge plate being 28 metres (92 ft.) high. The hall is 280 metres (919 ft.) in total length ; the trusses rest on ornamental brackets fitted in the walls. On each side of the central bay there are two smaller