"No air?" repeated Rollo.
"No," replied Jonas; "it is all close and solid around; the air cannot get in."
"It can get in at the top," said Rollo.
Jonas made no reply to this remark, but walked away a few steps, to a place where he had put down his axe; he took up the axe, and brought it to the stump. He immediately began to cut into it, at the bottom, as if it were a tree which he was going to fell.
"O Jonas," said Rollo, "don"t cut it down."
"I am not going to cut it down," said Jonas; "I am only going to cut a hole into it."
"What for?" asked Rollo.
"To let the air in," replied Jonas.
Jonas continued to cut into the side of the stump, near the ground, until he perceived that the edge of his axe went through into the hollow part. Then he cleared away the chips a little, and showed Rollo that there was an opening for the air.
"Now," said he, "I presume you will be able to make sticks and birch bark burn in the stump, though you can"t make the stump itself burn very well."
Rollo now dropped a blazing piece of birch bark into the stump, and, to his great joy, he found that it continued blazing, after it reached the bottom. He then dropped in another piece upon it, which took fire. He then gathered some dry sticks, and put in; and, finding that the flame was increasing, he proceeded to gather all the dry and combustible matter, which he could find around, and put them in, so that in a short time he had a fine blaze, a foot above the top of the stump; and the inside of the stump itself seemed to be in flames.
"Jonas," said Rollo, "it does burn."
"Does it?" said Jonas; "I am glad to hear it."
"But you said the stump would not burn."
"You ought to wait until it is all burnt up, before you triumph over me."
"Why, Jonas," said Rollo, "I didn"t mean to triumph over you; but why would not the fire burn before you cut the hole through?"
"Because," replied Jonas, "there was not air enough."
"There was air in the stump," said Rollo.
"Yes," replied Jonas, "but all the life of it was consumed by the first piece of birch bark which you put in."
"The life of it?" said Rollo.
"Yes," replied Jonas; "what do you suppose it is, that makes anything burn?"
"Why, it burns itself," said Rollo.
"No," answered Jonas; "the air makes it burn: it must have good air around it, or else it won"t burn. There is something in the air which I call the life of it; this makes the fire burn. But when this is all gone, then that air will not make fire burn any longer. It will only burn in good fresh air, which has got the life in it."
"I thought fire would burn in any kind of air," said Rollo.
"No," replied Jonas; "you can see if you stop up the hole I made here."
Jonas then took a piece of turf from the field, and put it before the hole, and crowded it in hard with the heel of his boot. Rollo observed that the fire was almost immediately deadened.
"Now," continued Jonas, "light a small piece of birch bark, and put it in."
Jonas helped Rollo fasten a small piece of bark upon the end of a stick, and then Rollo set it on fire, and held it down a little way into the stump. It burned very feebly.
"See," said Jonas, "how quick it is stifled."
"Yes," replied Rollo, "it goes out almost directly."
"You see," said Jonas, "that the fire already in the stump consumes all the goodness of the air; and I stopped up the hole, so that no fresh air can come in."
"Why doesn"t it go in at the top?" said Rollo.
"It does a little," said Jonas, "but not much, because the hollow of the stump is already full of bad air, and there is nothing to make a current. When there is an opening below, then there is a current up through."
"Yes," said Rollo, "it is just like a chimney."
"Yes," replied Jonas, "the stump is the chimney, and the hole is the fireplace."
"And the air in the stump," said Rollo, "gets hot, and so the cold air all around is heavier, and so it crowds down under it, and buoys the hot air up out of the stump. My father explained it all to Nathan and me."
Rollo then wanted to open the hole again, to see if the effect would be as he had described.
Then Jonas pulled away the turf from the hole at the bottom of the stump, and Rollo observed that the fire brightened up immediately.
He then held a smoking brand near the hole, and he saw that the smoke was carried in, in a very strong current, by the cool air, which was pressing into the hole.
"Yes," said Rollo, "it operates just like a fireplace."
"So you see," continued Jonas, "that whenever you build a fire, you must see to it, that there is an opening for air to come up from underneath it. And it must be good fresh air too."
"What is it in the air, which makes the fire burn?" said Rollo.
"I don"t know what the name of it is," said Jonas; "it is some part of the air, which goes into the fire, and is all consumed, and then the rest of the air is good for nothing."
"Isn"t it good for anything at all?" asked Rollo.
"I don"t know," said Jonas, "how that is; only I know that it isn"t good for anything for fires. It stifles them."
"I should like to know what the name of that part of the air is, which is good for fires," said Rollo.
"I knew once," said Jonas, "but it was a hard word, and I have forgotten it."
"I mean to ask my father," said Rollo.
Jonas then went on with his work, gathering up everything that he could find around the field, to put upon the fires. Rollo amused himself by putting large rolls of birch bark around the end of a stick, and then, after setting them on fire, holding them over the fires, which Jonas was making, to see how soon the flame was extinguished: then he would draw them away, and see them revive and blaze up again in the open air. At last, he called out to Jonas, once more.
"Jonas," said he, "I have found out what makes the blaze go out. It is the smoke. I don"t believe but that it is the smoke."