In A Christmas Carol by Charles Dickens, mentioning the size of Scrooge’s fire compared to that of his clerk Bob Cratchit’s is significant because it underscores how stingy Scrooge is. Scrooge is too cheap to have a robust fire himself, but he provides even fewer coals for Bob Cratchit. Bob works in the outer office. Because Scrooge cannot part with money, Bob’s work area is small and meager. It is a “dismal little cell beyond, a sort of tank.” The author writes about their fires:
Scrooge had a very small fire, but the clerk’s fire was so very much smaller that it looked like one coal. But he couldn’t replenish it, for Scrooge kept the coal-box in his own room; and so surely as the clerk came in with the shovel, the master predicted that it would be necessary for them to part.
Cratchit’s fire is small, and he is afraid to replenish or enlarge it. He fears that if Scrooge sees him approach the coal-box, Scrooge will dismiss him from his job. Importantly, in Victorian England, the fire was generally the only source people had to keep themselves warm during the cold winter months.
Bob overhears a conversation between Scrooge and his nephew and is so overcome by the nephew’s remarks that he applauds. He then stokes his fire in an effort to cover up. Unfortunately, because it is so small, the fire goes out. Dickens drives home the point that Bob’s fire is so weak by describing it as “frail.” It is not sufficient to keep him warm and he must wear a heavy "comforter." This is consistent with the Christmas scene at Bob’s home, when it is made clear that Scrooge pays Cratchit so little that he is not able to provide much for his family on Christmas.
The author maintains the imagery of the cheap fire when Scrooge returns to his home. Dickens notes how dim the fire is in both the lamps and hearth for light and warmth:
And in his rooms, It was a very low fire indeed; nothing on such a bitter night. He was obliged to sit close to it, and brood over it, before he could extract the least sensation of warmth from such a handful of fuel.