Iron before industrialisation
Iron has been produced in some form since prehistoric times.
Like most of the leading sectors in the industrial revolution the iron industry had a long history. By the beginning of the eighteenth century it was already a comparatively advanced industry, with heavy fixed capital equipment in the form of furnaces and forges. Wrought iron had been produced from the time of the Middle Ages, if not before, through the firing of iron ore and charcoal in equipment called a bloomery. This method had been replaced by the blast furnace from the 1490s onwards. With the aid of water-powered bellows the blast furnace permitted both increased output and continuous production.
The traditional use of iron in architecture was principally as dowels, cramps or ties to strengthen masonry structures.
As early as the 6th century iron tie-bars had been incorporated in the main arcades of Hagia Sophia in Instanbul. Renaissance domes often relied on linked bars to reinforce their bases. Such customary uses reached a new degree of sophistication in Jacques Germain Soufflot's design for the portico of the Pantheon in
