Shrewsbury, England
The Industrial Revolution gave rise to a new building type: the factory, where a managed workforce could operate machines that were driven by steam power. The advent of machines also created a demand for iron to be produced on a large scale in addition to being used to build machines, it soon became apparent that iron could be used to construct industrial buildings. The forerunner was the prefabricated cast-iron bridge at Coalbrookdale, England, of 1775 1779. But the factories, especially textile mills, involved problems other than the structural ones. Because they handled large quantities of cotton, flax, and wool, and because their wooden floors were quickly saturated with the oil used to lubricate the machines, they presented a fire hazard. The earliest textile mills had timber floor and roof framing and solid masonry external walls. Cast iron was non-combustible, and it was believed that it offered, as well as greater strength, a measure of fire resistance. Designed in 1795 and built the following year by the engineer Charles Bage of the milling firm of Bennion, Bage, and Marshall, the Ditherington Flax Mill, in the Shropshire town of Shrewsbury, was the worlds first iron-framed building, the predecessor of most modern factories and even office blocks. Ditherington was the largest flax mill of its day and one of the largest textile mills of any kind in Britain. The five-story building has conventional load-bearing masonry external walls with very large windows. Internally, it is divided into four bays by three rows of slender, cruciform-section, cast-iron columns, extending for eighteen bays on a north-south axis. Each bay measures about 10 feet 3 meters square, and the average ceiling height is about 11 feet 3.4 meters. The columns support cast-iron beams spanned by the brick vaults that form the floor above. The nearby warehouse and cross mill, also iron framed, were built soon after. In 1846 Professor Eaton Hodgkinson published Experimental Researches on the Strength