832 Transactions of the American Institute. 



The French methods and designs have been used in our country; 

 especially the method of constructing the cables du'ectly on the 

 towers, in the year 1844, at the Alleghany suspension bridge, near 

 ^Pittsburg, and Vicat's invention was a little but not essentially modi- 

 fied at the construction of the Niagara and Cincinnati suspension 

 bridges by Roebling. 



A picturesque suspension bridge is that at Cubzac, across the 

 river Dordogne, in France, with five continuous spans of 363 feet 

 each, the towers being constructed of iron (iron towers eighty-two 

 feet high; total height of towers above low water=:126 feet). 



Iron towers also are used at the chain bridge at Seraing, in 

 Belgium, and at the chain bridge at Muehlheim, on the Euhr, in 

 Prussia. 



Since the accident of the wire bridge at Angers, in France, in the 

 year 1850, many of the wire bridges in Paris have been replaced 

 by truss and arch structures, and a law is introduced directing tests 

 of wire bridges from time to time. During such a test in the year 

 1861, the suspension bridge at Mirabel sur L'Eggues broke down, 

 the cable having been destroyed by rust in the interior. 



The elder Seguin, in the year 1840, had an opportunity to apply 

 the old American method of stiffening suspension bridges, which 

 he appreciated highly, as has been demonstrated. He was the first 

 man, at least in Europe, who built a suspension bridge for railway 

 purposes, and with full success. 



His work was an auxiliary suspension bridge across the Soane 

 river, built in the year 1840, when some spans of the wooden rail- 

 way bridge were swept away. The two spans of his bridge were 

 137.5 feet each, the deflection of the cables was 16| feet, girders 

 8^ feet high, composed of wooden beams nine inches by 2^ inches, 

 and chords of 13 inches by 6^ inches, connected with the longitu- 

 dinal beams of the floor by screw bolts, and kept in vertical posi- 

 tion by braces, were to stifien the floor vertically. The three cables 

 on each side were connected by numerous ligatures. This new 

 bridge was reported to have been as stiflf as the former truss bridge, 

 and was used as a railroad bridge during four 3'ears with perfect 

 success, and then the remaining wooden frame bridge, as well as 

 the suspension bridge, were replaced by a stone structure. 



This bridge, also, had neither stays to support the floor, nor stays 

 to add for horizontal stiffness. 



Our Vice-President, Mr. Julius W. Adams, kindly showed me a 

 plan of a stiffened railroad suspension bridge across Kentucky river, 



