224 Class

Thomas Wheatley, Locomotive Superintendent of the NBR from 1867 to 1874, designed in 1871 a 4-4-0 with inside cylinders and a leading 4-wheel bogie — the first British locomotive of this layout, which would later become the dominant British 19th-century express type. Two were built at Cowlairs in 1871, numbered 224 and 264.

No. 224 was hauling the regular mail train from Burntisland to Dundee on the night of 28 December 1879 when, mid-crossing of the Tay Bridge in a violent storm, the central spans of the bridge collapsed into the firth. The train and all 75 passengers and crew were lost. The engine was recovered from the river bed in 1880, comprehensively repaired, and returned to NBR service — uniquely among British locomotives, having been completely submerged in salt water and then rebuilt. The class was nicknamed "the Diver" thereafter.

The engines worked NBR services until withdrawn in 1919. Neither was preserved, but the locomotive's role in the Tay Bridge disaster makes 224 one of the most historically significant Victorian engines.

Inside-cylinder 4-4-0 with 6 ft 6 in coupled wheels, leading 4-wheel bogie, parallel boiler with brass dome.

• No. 224 "The Diver" (1871, not preserved — recovered from the Tay 1880, withdrawn 1919)