Iron Duke 4-2-2 locomotive, 1851.

UNITED KINGDOM - SEPTEMBER 04: Working replica made by Resco Railways Ltd, 1983-1985, shown in Kensington Gardens, London. The locomotive represented by this replica was designed by Sir Daniel Gooch (1816-1889) to run on Brunel's broad gauge tracks on the Great Western Railway (GWR). Gooch trained with Robert Stephenson in Newcastle and was the locomotive superintendent for the GWR for 27 years. The broad gauge measured 7 foot compared to Stephenson's standard gauge of 4 foot 8 1/2 inches and was eventually superseded because of the inconvenience of having to transfer passengers and goods between the two standards of track. The 'Iron Duke' class locomotives were capable of attaining speeds approaching 80 mph. (Photo by SSPL/Getty Images)