MECHANICS AND USEFUL ARTS. 31 



. cost $2,000,000. It is 2,000 feet in length, and i^ only for a com- 

 mon road. The Ohio River Railway Bridge at Louisville is to be 

 1,650 feet longer, beside the pivot bridge across the canal, and the 

 whole cost will not exceed $1,500,000. 



THE CERE VIADUCT. 



This fine structure, crossing the valley of the Cere and carrying 

 the Paris and Orleans Railway at a height of 181| feet from the 

 water, is another and more complex and lofty specimen of the 

 modern style of bridges supported on tubular piers. Each of 

 these consists of 8 cast-iron columns, grouped in an ellipse, 

 united by cross bracing, and resting on a base of brickwork. 

 The piers taper upward from a base of about 8 x 16 feet, at a rate 

 of 1 in 30 toward the major axis, and 1 in 15 toward the minor 

 axis of the ellipse. There are 5 spans of lattice girders, the 

 3 central spans being 164 feet each, and the end spans 145 

 and 139. The abutments are of stone. The erection of this via- 

 duct was conducted in the same bold manner as that adopted at 

 Fribourg, the girders being first put together on the abutments, 

 and then pushed forward until the overhanging ends were over 

 the brickwork base of the first of the iron piers to be erected. 

 They were then braced, and used as the jib of a crane for hoisting 

 into .ilace the successive joints of the tall iron limbs upon which 

 they were to rest. When one of the piers was thus completed, 

 the girders were again pushed forward until the foremost end 

 rested on it and projected forward over the base of the second 

 pier, and the same process as before was repeated until the struc- 

 ture was complete. The total cost was about $150,000. 







SUSPENSION BRIDGE OVER THE OHIO RIVER AT CINCINNATI. 



This, lately completed from' the plans of Mr. J. A. Roebling, 

 has a span of 1,057 feet, the largest existing span of a suspension 

 bridge. It crosses the river with a clear headway of 100 feet 

 above low water, the greatest variation between the summer low 

 level and that of the spring freshets being 60 feet. The massive 

 towers of masonry rise 200 feet above low water. The supporting 

 members of the bridge are two cables of parallel wires, of No. 9 

 gauge, each cable being 12 inches in diameter, and containing 

 .5,250 wires, the breaking strength of the wire being over 60 tons 

 per square inch of net section. Nearly half of the weight of the 

 roadway and load is carried by diagonal wires, running straight 

 from the tops of the towers to successive points along the floor, so 

 that the main cables, stiffened by this arrangement, really carry 

 but about half of the total weight of the roadway and load. 

 Length, 2,000 feet; cost, $2,000,000. 



NEW YORK AND BROOKLYN BRIDGE. 



This contemplated bridge across the East River, on the plan of 

 Mr. J. A. Roebling, with a headway of 130 feet in mid-channel, 

 will have a great suspension span oi' 1,GUO i'eet in the clear, nearly 



