iron. Widely used in architecture. There are two basic types: cast iron, which is strong in compression, but weak in tension, so is used for columns, bollards, railings, and decorative features; and wrought iron, which is employed for gates, ornamental scrolls, filigree-work, and the like. Some fine medieval ironwork survives, notably associated with English tombs and chantry-chapels in cathedrals and churches. Later, iron was widely used for balcony-fronts, railings, etc., in C18. Exposed cast iron was used for components in whole façades in C19, notably by John Baird in Glasgow, and wrought iron was used to construct large trusses spanning wide spaces. There are many C19 catalogues of cast-iron components, notably by Badger in the USA and the Saracen Factory, Glasgow. Fairbairn's On the Application of Cast and Wrought Iron to Building Purposes (1854) was an important publication. Iron-and-glass structures were developed for conservatories, railway-stations, exhibition-buildings, and the like, notably by Paxton, Loudon, and others. Iron was used structurally, starting with late-C18 bridges such as at Coalbrookdale, Salop. (1777–9), Sunderland (1793–6), and Buildwas, Salop. (1795–6), and then for factories and warehouses, notably at William Strutt's Mill, Derby (1792), and the Marshall, Benyon, & Bage Mill, Shrewsbury, Salop. (1796), both of which had cast-iron columns carrying systems of beams from which sprang brick vaults. Developments in iron structures occurred when composite girders and columns were made, using rivets, and gradually framed buildings were evolved, permitting speed of erection, great heights, and light claddings. Ultimately, the steel frame permitted the building of skyscrapers. See also metal structures.

Bibliography

Fairbairn (1849, 1869, 1870);
Fairbairn & and Pole (1970);
Gayle & and Gillon (1974);
G. Hartung (1983);
Lemoine (1986);
Loudon (1834);
Mainstone (1975);
Sturgis et al. (1901–2)