Great thread Senter Cove Guy!
Could the big drum that is not part of the Mount be part of the train station? The old building came way out from the shore and the drum is not in any of the old photographs. I can find no mention of what fuel was used. Wood seems to be the most common, as it is readily available.
Perhaps this scan of her plans might help. Taken from Farewell Old Mount Washington. The picture is huge to allow greater detail, so I am putting it as a link to PhotoPost.
Mt. Washington Boiler and Engine Plans