On Jul 29, 11:23*am, Andy Breen wrote:

Reading this prompts another thought, regarding the development of
locomotives in the earlies. I've not seen it listed before, but surely
one of the major advantages of a separate firebox (as adopted by
Stephenson's works from Rocket onwards, though not by some other builders
until much later [1]) is that it would allow the fire to be dumped
reasonably easily

The biggest difference is that a furnace in a flue can burn coal,
unlike Rocket, which had to burn the more expensive coke. It wasn't
for a few decades after Rocket prompted the switch to Stephenson's
more powerful firebox and thus a more compact locomotive, before the
invention of the brick arch allowed a return to coal burning.