Bridges presentation
Philadelphia. The USA contributed little more until the middle of the century, but these inventions
were immediately followed up in Europe. The French and Swiss continued to use wire cables,
developing methods of fabricating the cables in situ. In 1822, Marc Séguin proposed a suspension
cable made up of one hundred thin iron wires, erected his first suspension bridge (actually a catwalk
like the White and Hazard bridge) over the Cance at Annonay, and proposed a major structure over
the Rhône at Tournon. By scientific testing, he proved the strength of the wire cable - twice that of
the English iron eyebar chain - and described all in Des ponts en fil de fer, published in 1824. The
world's first permanent wire-cable suspension bridge, designed by Séguin and Guillaume-Henri
Dufour, was opened to the public in Geneva in 1823, followed by Séguin's Tain-Tournon Bridge, a
double suspension span over the Rhône, completed in 1825
annaabi.ee 
