The other girls left their tasks and watched the lesson in fire-building. Nita said, "Why not—I should think the easiest way would be to drop a match down to the paper while you have the stove-lid off!"
Miss Miller felt well repaid for her trouble by seeing Nita sincerely interested.
"First, the smoke rises and may cause one unpleasant choking or watering eyes. Then, too, the open lid prevents the draft that circulates from chimney down the back of the stove and underneath where ashes accumulate and up against the fire-pit to force a fire higher. If you lean over I will show you the back-damper."
Miss Miller took off the last back lid on the top of the stove and showed the girls a closed damper. By pushing in a small key just over the oven which the girls had never noticed on a stove before, she demonstrated how the little door dropped back and left the current of air and smoke to escape from the fire and rise through the chimney. She also pointed out the wide mouth at the back of the stove that permitted the air from the chimney to go down and find its way into the ash-pit directly under the fire.
"If your ash-pit is filled with ashes the fire never will force any heat into the oven, of top-lids. It may burn slowly, but not until the ashes are removed can you look for any right result in your stove! Lazy house-keepers dislike to take out ashes and keep on heaping coal on top of their fire; that only burns out the enduring qualities in your stove top. A fire that barely reached to the top of the fire-pit is always best, and to keep it at that height you must keep the ashes that are always forming under the fire well raked down until you see a red reflection at the under side of the grate. If you do not quite understand, I can show you later, when the cake is in the oven."
Nita then knelt down before the fire-pit and carefully placed a burning match under the paper. It flared up and in a few seconds, they all heard wood crackling. But smoke backed out of the lids and seemed to be ready to burst the stove-pipe.
"Oh, Miss Miller, what's wrong?" cried Zan, anxiously.
Miss Miller smiled and said, "After my lesson, can't one of you discover the trouble?"
The girls coughed and rubbed their eyes but no one had an idea what to do. Smoke kept pouring forth while they looked about for some clue to the knowledge which the Guide seemed to keep to herself. Finally, they had to give up, and she immediately took hold of a key, similar to the oven damper, that was seen in the stove-pipe, and turned it up vertically. Immediately the smoke was released into the chimney, it stopped coming from the stove.
"Well! what a simple thing to do!" exclaimed Zan.