The lesson then took up heating the ovens, which was still more important. Her mother showed Margaret how to push in and out the dampers over the oven doors, and explained the shutter inside which they worked. "When we want the oven hot we pull the shutter open to let the heat go all around the oven. When we want to cool it we shut the shutter. The first thing to learn about a stove is this: find out whether the damper is pushed in or pulled out to heat the ovens; you can tell by taking off the top covers and watching, for you can see in that way how the shutter works. Some push in and others pull out, and each stove may be different. These push in when you want to get the oven hot. Now, if you want to cook on top of the stove, and want all the heat up there, of course you do not need the ovens heated, so you shut them away. When you are all done with the fire never let it burn uselessly, but close it up, and so keep it. The reason of the draft in the front of the stove at the bottom, is this: the air rushes in up through the coal and on into the chimney, and makes the fire go hard. If you want to have it go slowly and not waste the coal, of course you must shut this tight. The other draft, directly in front of the fire, lets the cool air right in on the hot coals, and keeps them from burning up rapidly, so if you want a hot fire you must shut this, and when you want the fire to go down you must open it. Is that plain?" "Yes," said Margaret, thoughtfully. "When I bake I make the ovens hot by pushing in the dampers, and opening the slide at the bottom and shutting it at the top. When I want to make something on top, I pull out the dampers to get the ovens cool, and I open the one at the bottom and shut the one at the top. When I'm all done I leave the oven dampers out, shut the bottom draft in front and open the top one. Then the fire gets cool. But what do I do to the chimney dampers?" "Sure enough," said her mother, "we almost forgot those. You see the queer handles on them--thin and straight; those are like the flat plates inside the pipe that turn just as they do. When you want the fire to burn hard you turn the handle along the pipe, and that turns the plate the same way, and the heat can get out and make a good draft. But if you are shutting up the fire you turn the handle across the pipe, and that makes the plate turn straight across, too, and stops the heat from getting out, and so the fire dies down." "Oh, yes," said Margaret, "that's easy to understand. But what do people do who don't have coal fires? Sometimes they have wood to burn." "But the dampers and drafts all work the same way," said her mother. "Wood is nice and clean to burn, and makes a quick, hot fire, but it has to be watched all the time or it will go out. Coal makes a steady heat, and so for most things it is better to use. Now look in and see how things are going."