Well, what was installed on the 4100 was the large pipe running from the engineer's side of the steam dome, along the upper side of the boiler, and terminating in a plug on the smokebox front. Both Mister Nutbar and I thought that this was for a snow "melter" - the original version of the jet-powered one that came later:
However, the term used in the CNR SIG Magazine called the device a Barber Green Snow Loader, although no explanation or photo of this device was offered. I googled "Barber Green Snow Loader", and it came back with a description of the device used to clear snow from city streets - it picks up the snow, then uses an integral conveyor to transfer it to waiting trucks. We are guessing that the railroad device was a steam-powered version that was pushed by the locomotive, gathering snow in yards or urban areas, and transferring it to gondolas, most likely between the loco and the loader. However, this is just a guess: we would welcome comments from anybody with more info on this machine and its operation. A photograph would be nice, too.
Wayne