Construction of the tubes for the Britannia Bridge, 1848.

UNITED KINGDOM - JUNE 30: Lithograph by G Hawkins after his own drawing, showing the platform and the construction of the tubes in September 1848. The bridge was designed by Robert Stephenson (1803-1859) and was completed in 1850. It was constructed to provide trains of the Chester and Holyhead Railway with a passageway across the Menai Straits from mainland Wales to Anglesey. The railway terminated at Holyhead, which became a major port for travellers to Ireland. From �The Britannia and Conway tubular bridges� by Edwin Clark (1814-1894), published in London in 1850. (Photo by SSPL/Getty Images)