Very useful information. Interesting to see the differences with some of American practice, particularly on wide-firebox stoker-fired engines (compare the 1947 Reading 'book' on firing).

I presume that much of the 'skill' of firing -- where to put the '4 to 6 scoops' on the grate, when to rake or break up clinker, etc., would be 'known' to firemen and not covered here.

Is the 'split' of heat release between carbon and volatile matter described in this film applicable primarily to relatively small narrow-firebox engines? They seem to be assuming that carbon combustion occurs completely in the firebed and not above it, and also that the volatiles provide twice as much heat as the carbon in terms of making steam -- which would have to indicate restricted radiant absorption for effective steam generation (as late American practice would understand it). I had thought that one important aspect of a locomotive fire involved volatilizing the carbon so it would form a proper 'luminous flame' (with the luminosity directly related to the radiant heat transfer in zones of the firebox). I further thought that one purpose of 'intentionally lean' combustion of the volatiles (which is the real thing they seem to be espousing by 'firing to a light grey haze') was to get the 'invisible gases' reduced to carbon that would be heated to incandescens nfor best heat transfer as long as possible... I note they discuss cold-air impingement on the tubeplate but not soot accumulation there, whereas in another of these videos (on LMS locomotive maintenance) they make a point of how soot has to be blown out of the flues and elements each time.

This in turn was reminiscent of an article that used to be present on the Catskill Mountain archive (but I can no longer find it there) -- I believe it was a Railroad Magazine piece from the early 20th Century, about a 'college boy' who tries to make clean smokeless combustion the rule for 'efficient' locomotive firing but is set straight about why smoke is necessary in some practical circumstances.

Other interesting details, too -- I had not seen the disciplined use of that movable deflector plate before, or the careful nudging of the firedoors (with bare hands, unless I missed something, to get the secondary air just right. That method is highly likely to work better on narrow (and perhaps comparatively long) fireboxes than on typical late American power. What I wonder now is, if 'guns' or jets were in use for optimizing secondary air a la Porta, rather than just absolute smoke reduction in start-and-stop city or yard service, what combination of jet pressures/volumes from front to rear, combines with what sort of plume from the backhead and door/deflector, would be required for most effective combustion?