I came across this term.
It is used in the following paragraph:
"This locomotive is fitted with a re-entering fire door and the very small amount of smoke issuing from the top of the stack showed the advantage of admitting air to the firebox above the fire and deflecting it downwards upon the bed of incandescent coal."
Can anyone explain what a re-entering fire door is?

http://www.azohwy.com/y/ymavlyrr.htm
hankmorris@earthlink.net