large piers and the upper part of these in the form of an arch was so arranged as to follow accurately the curve of the inner surface of the proposed arch (that is to say the intrados) at its springing. Upon these centers were placed the corresponding metallic pieces and after this part of the arch had been constructed it was connected by means of twenty steel cables with the straight superstructure to Lthe right. From this moment it was possible to begin the mounting of the projecting arch according to the method previously applied by Mr. Eiffel to the Douro bridge. The opera tion of joining the pieces proceeded by degrees care being taken when the weight of the overhanging part became too great to put a new series of anchoring cables in position connecting the pier extremity with the upper superstructure. Figs. 1 and 2 well show in what the process consists. The placing of these cables permitted of raising or lowering the parts of the arch in process of being mounted in every stage of ad vancement. The special arrangements made to this effect were as follows : The ends of the cables rested upon iron girders through the inter medium of wedges that could be disengaged by means of hydraulic presses. It was one the loads remained stationary in the other they were rolling. The test loads consisted of a 75 ton loco motive hauling 15 ton cars and the results obtained are worthy of being cited as they demonstrate the surprising fixedness of the structure. The arch loaded for its entire length by a train of 22 cars (Fig. 3) exhibited under this enormous weight of 405 tons a deflection of 027 inch. The same train placed upon one of the halves of the arch produced a deflection at the key of but 015 inch. Finally under the action of the rolling weight the deflection was but 0 46 inch. These figures are significant. They constitute per haps for people who are informed the finest eulogy that can be addressed to the eminent constructor Mr. Eiffel wh after the Garabit viaduct wil
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