ABSTRACT
The steel beam, introduced about 1885, is one o£ the most important components o£ modern architecture and structural engineering. It took the place o£ the wrought-iron beam which, in its tum, replaced the cast-iron beam around 1850. But the cast-iron beam was the first metallic beam to be used· consistently as a major element in building construction. Previously timber had been emp]oyed £or this purpose. Consequently in tracing the origin o£ iron beams we are concerned also with the origins o£ a basic change in construction practice.
