Les armatures de fer de la cathédrale de Bourges : nouvelles données, nouvelles lectures

Abstract

The Cathedral Saint-Etienne in Bourges is the first major Gothic building to have been examined with regard to the use of iron in its construction. The study, made in the 1990s, posed questions about the role and origin of the iron armatures identified in the structure of the edifice. Increased research in this area in the intervening years and the development of archaeometric methods applied to metals have allowed us to cast new light on these questions. The present article publishes the results of an archaeological study of the construction of Bourges Cathedral undertaken in 2010-2011, in conjunction with the chemical analysis of 70 iron samples and 58 lead sealings. The integration of the armatures in the masonry, as well as their chemical composition, reveals that the truss rods and chains installed in the triforium are contemporary with the rising structure, but that their installation was not foreseen from the beginning. They were implanted only after construction was under way, probably in order to consolidate disorders observed in the unfinished structure. The results of this study make Bourges Cathedral a benchmark in the history of the use of iron in Gothic architecture and herald a reconsideration of the evolution of the know-how of medieval builders with regard to the progressive integration of this material in masonry in the early thirteenth century, the fruit of constant experimentation.