The Works Of Messrs. Schneider And Co.

138 MESSES. SCHNEIDER AND CO.’S WORKS. longitudinal floor line of the whole bridge is an arc of circle with a radius of 5,206 metres ; it meets the abut- ment walls at an incline of 1 in 50. The pi’incipal dimensions of the arches are as follows : — Openings. Rise. Depression. Radius. Central arch ... End arches m. 67.40 64.00 m. 4.44 3.96 1 15.18 1 15.91 m. 130.113 127.264 This work is remarkable from an architectural point perature approaching the average ; therefore the arches act, under the action of permanent loads, as being jointed at the springing ; and under the action of extreme tem- peratures and surcharges, as being rigid owing to their bearing over the whole of their height. The trials proved, moreover, that in this way the vibrations had been pre- vented as far as was practicable ; diagrams taken during tests show them not to have exceeded 0.0015 in. any- where. The construction at the works, and the érection on the Fig.dQô Se<^tony A .B . C .1) . Ö O; O b O; O O 10 O O ÿw«.-«3 s s -3.G3a 1 °'; o" o‘ O C; Details of the Morand Bridge over the Rhone at Lyons. of view, and it may be said it solves admirably the difficult problem that had to be met, inasmuch as all the inconveniences that might have arisen through such a limited rise have been done away with. The division of the width to be bridged, into one central, and two end, arches, was determined in such a way as to balance the pressures on each side of the piers under average conditions of temperature and equality in the load on the side spåns. The ribs rest on hinges at the springing, and are continuons at the key. The hinges were wedged after completion of the work, and at a tem- spot, were conducted with great success, and the bridge was completed without the least accident. The foundations of the piers were made by means of compressed air caissons ; the excavations showed a suc- cession of layers of sand and gravel, which constitute, to a great depth, the subsoil of the Rhône bed. The foundations of the abutments, not being exposed to damage by water, were not made deep ; those of the piers, on the contrary, were carried 12.600 and 13.920 metres (41 ft. 4 in. and 45 ft. 10 in.), as undermining was to be feared owing to the great rapidity of the river. The 1