Multi-Tube Boiler

One of the principal design advances for the steam locomotive was the introduction of the multi-tubular boiler. It was suggested to George Stephenson by Henry Booth and was fitted to his Rocket locomotive of 1829. It also appeared in France at the same time on a locomotive built by Marc Séguin. Before this, locomotives had single flue boilers or return flue boilers.

The multi-tube boiler contained a number of hollow tubes that allowed the hot gases from the fire to pass through the boiler to the chimney at the other end. The distribution of the heating effect led to more efficient steam production and assisted with the forcing of a draught on the fire. This was different from certain other applications of multi-tube boiler, e.g. marine, where the water passed through the tubes and the heat was applied to the outside of the tubes.