The use of structural cast ironGlossary Term in building took off in the late 18th century and became increasingly popular in the 19th century until it was replaced by steel. There was some early success in the design of bridges and fireproof factories, but the physical properties of the material were not at first well understood.

Early 19th century Manchester, with its atmosphere of intellectual enquiry, its brilliant circle of scientist centred on John Dalton, and its pool of experienced founders and engineers, offered the ideal conditions for innovation. Eaton Hodgkinson, a former pupil of Dalton, began working on the design of cat-iroin beams with the help of the engineer William Fairbairn in the 1820s. Beams were made and tested in Fairbairn's (demolished) Ancoats works. The key was the correct analysis of tensile stresses. Hodgkinson devised a beam which was lighter, more efficient and cheaper than its predecessors. His finding, which were published by the Manchester Literary and Philosophical Society in 1830, formed the basis for all future 19th century structural cast-iron deisgn.

The new beam became standard in iron-framed buildings but the first known application was in George Stephenson's (demolished) Liverpool and Manchester Railway Water Street bridge of 1829-30 where the superior qualities of the beams facilitated the construction of a flat, level bridge, the prototype for the most common type in use today, the level beam or girderGlossary Term bridge.

You can see an example of this at the UMIST campus where part of the cast-iron frame of the 1840s Havelock Mills has been erected.