Northumbrian was an early steam locomotive built by Robert Stephenson in 1830 and used at the opening of the Liverpool and Manchester Railway. It was the last of Stephenson's 0-2-2 locomotives in the style of Rocket, but it introduced several innovations. It was the first locomotive to have the Stephenson type firebox incorporated in the boiler, and having a smokebox the full diameter of the boiler, it therefore had the first true 'locomotive' boiler. It also had plate frames, a proper tender, and the cylinders set at a relatively low angle to the horizontal, giving smoother running. The pace of development of locomotive design at the time can be seen by comparing this engine with Stephenson's Planet, produced later the same year.