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 the context of the first suspension bridge proposed over the Rhone River, France, in the early 19th Century. It was one of the most difficult rivers in Western Europe for bridge construction by classical means of masonry arches. No permanent bridge had been built there from the end of the Middle Ages. The design and application of iron wire cable for a major bridge (two spans of 85 m) was accomplished between the end of 1821 (start of the project) and the summer of 1825 (the Tournon-Tain suspension bridge). An exceptional archive source 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, and the relationship between experimental science and technology. The wholeness bears us a remarkable case study in technical innovation.

Author: M.J. Cotte