Earl of Airlie was an 1833 steam locomotive designed and built by J and C Carmichael for the 4ft 6in gauge Dundee and Newtyle Railway, with a 0-2-4 wheel arrangement and a tender.

The first locomotive in the world with a bogie, invented by John B. Jervis was Experiment (later renamed Brother Jonathan), a 4-2-0 design for the Mohawk and Hudson Railroad in the United States, in 1832.

[5][7] It used two vertical, single-acting cylinders of 11 by 18 inches (28 by 46 cm), one on each side of the boiler, mounted on top of the outside frames and driving the front wheels through bell cranks.

[5][7] Steam was provided by a fire-tube boiler at a working pressure of 50 pounds per square inch (340 kPa).

[5] It was delivered from its maker, J and C Carmichael, on 22 September 1833,[5] along with a separate tender comprising a wagon with a water-barrel affixed, costing £30.

[b] After being taken out of service, Earl of Airlie was used as a stationary engine, pumping water at Errol railway station.

[8] Around a decade later, Alexander Allan, who became locomotive superintendent of the Scottish Central Railway in 1863, recognised its significance of Earl of Airlie.

[8][10] He had it removed, cleaned, cosmetically restored (albeit with the wrong type of buffers; sprung, instead of horse-hair filled), painted, and then photographed.