Sentence:  He looked around his cab at his black greasy <WSD>fireman</WSD>, saying 'shovel on a little more coal, and when we cross that White Oak Mountain, you can watch Old 97 roll'. 
Meaning of the word marked with <WSD> tags:  A person (originally a man) who keeps the fire going underneath a steam boiler (originally, shoveling coal by hand), particularly on a railroad locomotive or steamship.