This volume covers the second great period of developments in iron construction from 1850, following its establishment as a structural material described in volume 9 of this series. Using the Crystal Palace of 1851 as a starting-point, the papers trace the history of iron-frame construction in Britain, France and America, and show its importance in fireproof construction, and in lattice truss and arch bridge design. A final group of papers illustrates the emergence of steel in framed buildings in both Britain and America. The selection brings out the important and daring contribution of individual engineers in their use of this material.