The invention of the cable made of numerous thin iron wires, Marc Seguin & Co, 1821-1825

The Seguin’s Brothers Company were responsible for the invention of the cable made of numerous thin iron wires (diameter from 2 to 3 mm) in context of the first suspension bridge projected over the Rhone River, France, early 19th Century. It was one of the most difficult rivers in Western Europe for the bridge construction by classical means of masonry arches. No permanent bridge was built there from the end of Middle Age. The design and application of iron wire cable for a major bridge (two spans of 85 m) was accomplished from the end of 1821 (start of the project) to summer of 1825 (achievement of the Tournon-Tain Suspension Bridge). An exceptional archive fund coming from the enterprises of Seguin’s brother, in Archives départementales de l’Ardèche, Privas, France, allows a deep study of this invention and its application to a major suspension bridge. Origins of the idea and its implementation were complex, but different roots must be surely identified: adaptation and evolution of foreign ideas, local craftsman culture, economical and socio-technical analysis, relationship between experimental science and technology. The wholeness bears us a remarkable case study in technical innovation.

Author(s): M.J. Cotte