The way in which it happened that Rollo’s father first began to explain to him something about the nature of fire, was this: It was one evening early in the autumn. Dorothy was going away to visit one of her friends, and Rollo was waiting for Jonas to come out, and see the fire-flies, or lightning-bugs, as he called them, which were flying about the yard. But Jonas did not come as soon as Rollo had expected, and so he went into the kitchen to see what had become of him. He found that, as Dorothy was rather late for her visit, and still had her kitchen fire to cover up, Jonas was just offering to cover it up for her, so that she could go at once without any further delay. So Rollo came in, and stood by the kitchen hearth to see Jonas cover up the fire.

The fire had nearly burned out, but it had left quite a large bed of embers, and a few coals among them. Jonas took the long-handled iron shovel, which belonged to the kitchen fire, and with it he drew forward all these coals and embers, so as to leave the back part of the hearth bare. Then he took the tongs, and with the tongs he gathered out from the hot ashes all the coals which he could find among the ashes, and put them back upon the bare place which he had made upon the hearth. He spread them evenly over it in a row against the back of the chimney.

“What are you going to do, Jonas?” said Rollo.

“I am going to cover up a stick of wood,” replied Jonas.

So Jonas opened a small door which led to a little wood closet by the side of the fire, and took out a short stick of wood, flat on one side and round on the other. It was a stick which was round first, but Jonas had split it in two. It was part of a great branch of a tree, large enough to make a good log, only Jonas saw that it would split easily, and so he had split it in two. The other half of it was still in the wood closet.

“This is just the stick,” said Jonas.

“Why?” asked Rollo.

“Why, the lower side is flat,” said Jonas, “to lie upon the coals, and the top is round, so that I can cover it all up the easier.”

So Jonas laid the stick down, with the flat side against the coals, and the round side outwards. Then with the great shovel he began to shovel the ashes and embers back over it. He put all the hot embers in first, and then the ashes, and he tried to cover up the stick entirely; but there was not quite ashes enough. One of the ends remained out.

“There, Jonas,” said Rollo, “now come.”

“No,” said Jonas, “I must cover the stick all up.”

“O, that little end won’t do any harm,” said Rollo.

“Yes,” said Jonas, “because, when the stick burns down, that place would make a hole, and let too much air in.”

“Don’t you want any air to get in?” said Rollo.

“Very little,” said Jonas. “I want a very slow combustion to go on until to-morrow morning, and then there will be a good bed of coals for Dorothy.”

“I don’t see why you take so much pains to cover up a stick of wood,” said Rollo. “You might light a fire with your tinder-box.”

“But it takes a great deal longer to make a good fire with a tinder-box, than when we have a good bed of coals.”

“Then take a friction match,” said Rollo. “I can light a friction match in half a minute.”

“You can light the match, but not build a fire. It takes a long time with a match light to get heat enough to set large sticks of wood on fire; but, with a bed of burning coals, we can do it very soon.”

“You might have some sticks and shavings for kindling,” said Rollo, “and they will burn quick.”

“Yes,” said Jonas, “but it is more trouble to prepare sticks and shavings every night, than it is to cover up a stick of wood.”

While Jonas had been saying these things, he had taken more ashes from the ash-hole, and had covered the stick over entirely. He then put away the shovel, and was brushing up the hearth, when Rollo, after standing a moment, as if in thought, said,—

“Jonas, what do you mean by combustion?”

“Did I say combustion?” rejoined Jonas.

“Yes, you said you wanted slow combustion.”

“Well, I meant burning. I want the wood to burn slowly all night.”

“Then why did not you say burning,” said Rollo, “so that I could understand you. I don’t see where you get all your learned words. I suppose it is out of some of your books.”

“Yes,” said Jonas, “they call it combustion in the books that I read, but I don’t know exactly why. I think there must be some difference between combustion and burning, but I don’t know exactly what it is.”

“I mean to ask my father,” said Rollo.

“But do you expect that that stick of wood will burn, Jonas?” continued Rollo, after a moment’s pause.

“Yes,” said Jonas, “it will burn slowly. A little air will get through the ashes so as just to keep it burning slowly. It is very dry.”

“Suppose that there could not any air get through at all?” said Rollo.

“Why, then,” said Jonas, “it couldn’t burn at all. It would go out. Sometimes I have buried up a fire so deep in ashes that it has gone out, and then I find nothing but black coals there in the morning, when I rake it open. That’s the way they make charcoal.”

“How?” said Rollo.

But Jonas had no opportunity to answer this question then, for they were just going out into the yard when Rollo asked it, and the attention of both the boys was attracted to the fire-flies. They, however, soon had looked at the fire-flies as much as they wished. Rollo tried to catch one, but he could not. He would see a flash at a little distance from him, and he would run to the place with his cap in the air; but, by the time that he got there, the fire-fly would of course have gone on to another place, though Rollo could not tell where, without waiting to see him flash again. Then he had to run again; but before he got to this second place the fire-fly would be gone again. One of the fire-flies led him a zigzag chase, in this way, all around the yard, and finally flashed at last just over the garden fence, so that Rollo gave up in despair.

In the meantime, Jonas had gone to the barn; and now Rollo went to see what had become of him. He found him shutting the doors up for the night, and then they both came back towards the house, and sat down upon the edge of the platform, under the piazza, and Rollo asked Jonas to tell him how they made charcoal.

“Why, they only bury up wood, as I did my log, lightly, so that enough air can get in, until it is burnt through; and then they cover it up tight, so that no air can get in, and so it goes out; and when it is all cold, they open it, and find the heap is all black coals.”

“How big a heap do they make?” asked Rollo.

“O, they make a very large heap, sometimes,” said Jonas; “as big as this.” So Jonas rose from his seat, and marked out a circle in the yard with a stick, which he had in his hand, in order to show Rollo how large a heap they make, when they pile up wood for a charcoal bed.

“And how high do they make it?” asked Rollo.

“As high as that” said Jonas; and he reached his stick up in the air as high as he could, to show Rollo how high the heap was.

“That must take a great deal of wood,” said Rollo.

“Yes,” said Jonas, “and when it is turned into charcoal, they get a great many loads of it.”

“How do they get ashes enough to cover it up?” asked Rollo.

“O, they don’t cover it with ashes,” said Jonas; “they cover it with turf.”

“With turf?” repeated Rollo.

“Yes,” said Jonas, “turf is the best thing to cover the heap with. If they had ashes, it would be very troublesome to put it on, and then it would be sliding down, and letting the fire break out. But they cut square pieces of turf, and cover the heap all over with them, very tight, and so only just air enough gets in to keep the fire slowly burning.”

“Slow combustion?” said Rollo.

“Yes, slow combustion,” said Jonas.

“How do you set it on fire?” asked Rollo.

“I believe they leave a hole in the middle,” said Jonas, “from the top down to the bottom, and then they put the fire down there.”

“I wonder if I couldn’t make a charcoal bed,” said Rollo.

“Yes,” replied Jonas, “you might make a little one, I suppose.”

“How should I do it?” asked Rollo.

“Why, you might take some dry wood from the shed, and wheel it down the lane, and through the gate into the pasture. Then you might take a spade, and cut up some turf, though that would be rather hard work for you.”

“I wish you would cut the turf for me,” said Rollo.

“Well,” said Jonas, “perhaps I will. Then you must hollow out a little place in the bare spot I make by taking up the turf, and make your pile of wood there, leaving a hole in the middle.”

“How can I leave a hole?” asked Rollo.

“Why, you can take three short pieces of board, as long as you intend the height of your pile to be, and stand them up on the ground, so as to leave a three-cornered space between them, and then pile your wood around the three boards.”

“So I can,” said Rollo.

“Your wood must be small,” continued Jonas, “or else you can’t pile it very snugly in a small pile. You had better take small round sticks, and saw them short, and lean them up against your boards all around, and so make a snug pile. After the pile is ready, you must bank up a little against the bottom of your heap with the loose earth, and then begin to put on the turf. But that will be a nice business.”

“Why?” asked Rollo.

“Because you must fit them carefully all around; and, as the heap will be round, and will grow smaller towards the top, square pieces of turf will not fit. You will have to cut them into shape with a knife. You can get an old knife to cut them with, and so fit them together. But you must fit them together well, or the air will get in, and your heap of wood will blaze up, and so it will be spoiled for charcoal.”

“I can make it tight,” said Rollo, “I know. I’ll shave away the sides of every turf, till it fits its place exactly.”

“There must be some air,” said Jonas, “or else the wood will not burn at all. You must leave a few holes around at the bottom, to let a little air in, then you can plug some of them up, if you find the fire burns too fast.”

“Well,” said Rollo, “I mean to make some charcoal some day. I’ll get my cousin James to come and help me. I’ll begin to saw up some wood for it to-morrow.

“But, then, Jonas,” he continued, after a moment’s pause, “what good will the charcoal do me when I get it made?”

“O, I don’t know,” said Jonas; “I wasn’t thinking of your getting any good from the charcoal. All the advantage would be, the pleasure of making it.”

“Isn’t there anything I can do with it,” said Rollo, “when I get it made? What is charcoal good for?”

“It makes a very hot fire. They use it when they want a great heat. Blacksmiths use it in their forges.”

“I wish I had a little forge,” said Rollo.

“They use it to make gunpowder, too,” said Jonas.

“How?” said Rollo.

“Why, they take some charcoal, and some sulphur, and some saltpetre, and pound it up together, and it makes gunpowder.”

“That’s what I’ll do with my charcoal,” said Rollo, jumping up from his seat. “I’ll make some gunpowder. I’ll ask my mother to give me some sulphur and saltpetre, and I’ll make some gunpowder.”

QUESTIONS.

What was the condition of the fire, on the evening when it was left to Jonas to cover up? Describe the arrangements which he made for covering up the fire. What was the shape of the stick of wood? Why was this form convenient for the purpose? What plan did Rollo propose, instead of covering up the fire? What objection did Jonas make to this plan? What term did Jonas use to designate the process which would go forward, during the night, under the ashes? What did he say that combustion meant? Would any air at all be necessary for the slow combustion? How was the necessary air to get access to the wood? Why could not Rollo catch the fire-flies? How did Jonas describe the process of making charcoal? What did he say were the uses of charcoal? To which of these uses did Rollo intend to put his charcoal, if he should succeed in making any?