Editing Stephenson's Rocket (section)

=== Boiler ===
''Rocket'' uses a multi-tubular boiler design. Previous locomotive boilers consisted of a single pipe surrounded by water (though the ''[[Lancashire Witch]]'' did have twin flues). ''Rocket'' had 25 copper{{sfnp|Snell|1973|p=84}} fire-tubes that carried the hot exhaust gas from the firebox, through the wet boiler to the blast pipe and chimney.  This arrangement resulted in a greatly increased surface contact area of hot pipe with boiler water when compared to a [[flued boiler|single large flue]]. Additionally, radiant heating from the enlarged separate firebox helped deliver a further increase in steaming and hence boiler efficiency.

The original innovator of multiple fire-tubes is unclear, between Stephenson and [[Marc Seguin]]. It is known that Seguin visited Stephenson to observe [[Locomotion No 1|''Locomotion'']] and that he also built two multi-tubular locomotives of his own design for the [[Saint-Étienne–Lyon railway]] before ''Rocket''. ''Rocket''{{'}}s boiler was of the more highly developed form, with the separate firebox and a blastpipe for draught, rather than Seguin's cumbersome fans, but ''Rocket'' was not the first multi-tubular boiler, although it remains unclear just whose invention it was.

The benefits of increasing the fire-tube area had also been attempted with [[John Ericsson|Ericsson]] and [[John Braithwaite (engineer)|Braithwaite]]'s ''[[Novelty (locomotive)|Novelty]]'' at Rainhill. Their design though used a single fire-tube, folded in three. This offered an increased surface area, but only at the cost of a proportionately increased length and so poor draught on the fire. Its arrangement also made tube cleaning impractical.

The advantages of the multiple-tube boiler were quickly recognised, even for heavy, slow freight locomotives. By 1830, Stephenson's past employee [[Timothy Hackworth]] had re-designed his [[return-flue boiler|return-flued]] [[Royal George (locomotive)|''Royal George'']] as the return-tubed ''Wilberforce'' class.{{sfnp|Snell|1973|pp=55–56}}