Oriental Company; and other vessels for the British Government, and many others, introducing iron shipbuilding on the River Thames. In 1848 he retired from this branch of his business. Fairbairn drew on his experience with the construction of iron-hulled ships when designing the Britannia Bridge and Conwy Railway Bridges. Railway locomotives Fairbairn began building railway locomotives in 1839 with an 0-4-0 design for the Manchester and Bolton Railway. By 1862 the company had constructed more than 400 at Millwall for companies such as the Great Western Railway and the London and North Western Railway. However, as the works had no rail access, any locomotives had to be shipped by road. Boilers Fairbairn developed the Lancashire boiler in 1844. In 1861, at the request of the UK Parliament, he conducted early research into metal fatigue, raising and lowering a 3 tonne mass onto a wrought iron cylinder 3,000,000 times before it fractured and showing that a static load of 12 tonne was needed for such an effect. He experimented with glass cylinders and was able to show that the hoop stress in the wall was twice the longitudinal stress. When a cylindrical boiler failed, it usually fractured along its length owing to the high hoop stress in the wall. This knowledge of how hoop stress increased with diameter, and how stresses were independent of drum length led to his invention of the Fairbairn-Beeley and his five-tube boilers, where a single large diameter shell was replaced by multiple smaller, and less stressed, shells. Eventually this would lead to the near-universal adoption of water-tube boilers with small tubes for high pressures, replacing the older fire-tube designs. Investigations Fairbairn was one of the first engineers to conduct systematic investigations of failures of structures, including the collapse of textile mills and boiler explosions. His report on the collapse of a mill at Oldham showed the poor design methods used by architects when specifying cast iron girders for supporting heavily loaded floors, for example. In another report, he condemned the use of trussed cast iron girders, and advised Robert Stephenson not to use the concept in a bridge then being built over the river Dee at Chester in 1846. The bridge collapsed in May 1847, killing 5 people who were passengers on the local train passing over the structure at the time. The Dee Bridge disaster raised concerns about the integrity of many other railway bridges