On Fri, 29 Jul 2011 07:36:14 -0700, Andy Dingley wrote:

On Jul 29, 11:23Â*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.

The S&D managed to burn coke for a few years (as a trial) in flue-type
'boxes, and coal in fireboxes. It produced rather a lot of smoke,
but as most of the land around the railway was owned by shareholders in
the company that wasn't an issue (the same, I think, could be said of
the other companies which burned coal - both in flue-type furnaces
and fireboxes - in the same era)

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.

Coke was mandated for smoke reduction, and firebox engines seem to have
been perfectly capable of burning coal (possibly with a different
arrangement of air-holes and firebars), ablet at the cost of a lot of
smoke.

Some railways were burning coal with (relatively) low smoke emission
before the brick arch too. Even neglecting the complex fireboxes of
McConnell, Cudworth and Beattie there was the arrangment of air-holes
in the box developed by Cowan on the GNoS in the middle 1850s that worked
so well that (IIRC) it was only under Pickersgill that they switched to
the brick arch (about 1900, I think...).

--
Andy Breen, not speaking on behalf of Aberystwyth University "The
internet, that wonderful tool for bringing us into contact with things
that make us wish we could scrub our brains out with dental
floss.." (Charlie Stross)