The Britannia Tubular Bridge, Wales, c 1850.
© Science Museum / Science & Society Picture Library
Plate taken from the 'Illustrated London News' (Vol 50/1 p 192). The Britannia Tubular Bridge spans the Menai Straits, connecting Anglesey to Wales. The idea of a single tubular girder inside which trains would run was conceived by Robert Stephenson (1803-1859) and completed in 1850. Each tube was 1,513 feet long and raised 100 feet above the water: its greatest spans were seven times the length of any previously constructed. After a test in which a 240-ton train crosed the bridge, it was concluded that 'all parts of the stupendous work obeyed the calculated requirements'. The Menai suspension bridge of Thomas Telford (1757-1834) is visible in the background.