Flue

The girl stood by the cold hearth and looked up into the dark throat of the chimney, where a narrow passage climbed out of sight. She asked Nyra why the opening above the fire was made so much smaller than the hearth below it, when a wider gap would surely let the smoke go up more freely. Nyra crouched beside her and pointed up into the shadow. “That narrow part is the flue,” Nyra said. “It is the passage that carries the smoke away, and it is made narrow for a reason.”

The girl frowned and leaned closer to the sooty brick. “A wide road is quicker than a narrow one,” the girl said. “Why should a narrow flue carry the smoke better than a broad one?”

“Because a narrow flue draws,” Nyra answered. “When the fire warms the air, that air wants to rise, and a close passage gathers it into one strong pull instead of letting it spread and cool. The draught lifts the smoke up and out, and cool air comes in low to feed the fire. A wide throat would let the warm air drift and stall, and the smoke would spill back into the room.”

The girl wanted the flue written into the book, the narrow climbing passage and the pull of the warm air and the soot that gathered on the brick. Nyra let her set it down, and watched the slow letters form. A book gathers what can be set down in a line and counted, and leaves the rest to the one who was there.

“You can set down the shape of the flue and the depth of it,” Nyra said, “but not the sound of a good draught on a cold night, nor the warmth that holds a whole room while the wind pulls at the roof.” The girl looked at the page, and then up into the quiet dark of the chimney, and she understood. The book keeps the flue, and you keep the draught of it.