After the explosion, James said that it was time for him to go home. It was about sundown. Rollo said that he would go home with him to keep him company, if his mother would let him. She had no objection, and Rollo and James went away together.

Rollo went with James to the door of the house where James lived, and then, bidding him good night, he left him, and began to return. When he had got about half way home, he saw a lady and a gentleman coming along the road. As he approached nearer to them, he found that it was his father and mother, taking a walk. Rollo joined them. They said, however, that they had walked far enough, and so in a few minutes they turned round, and went towards home.

“Didn’t our gunpowder go pretty well, father?” said Rollo.

“Yes,” replied his father, “better than I expected it would, without being more accurate in our proportions.”

“It was a very good experiment, I think,” said Rollo.

“Yes,” replied his father, “it was a good experiment, and it will prove useful to you, if it impresses upon your mind the nature of that property of gunpowder on which its power depends; namely, that its combustion is within itself. It doesn’t need the outward air.”

“Yes, sir,” said Rollo.

“There are other things that are more inflammable than gunpowder; that is, they will take fire more easily, and make a greater flame; but they cannot burn unless they have air. There is phosphorus, for example; it will take fire a great deal more easily than gunpowder, and I believe it will make a greater flame; but it must have air, and it can’t burn any faster than fresh air can get to it.”

“Then phosphorus will take fire easier than gunpowder,” said Rollo’s mother.

“Yes,” said Mr. Holiday; “that is, with a less degree of heat. I presume that, if I were to rub phosphorus in a mortar, it would almost certainly take fire. These friction matches are made of some composition of phosphorus, and the heat of rubbing the end upon a board is enough to set the composition on fire. But gunpowder would not burn by being rubbed so. But still, though less heat is required to inflame phosphorus than gunpowder, still air is necessary for the phosphorus, and it is not necessary for gunpowder; so that gunpowder will burn in confined places when phosphorus will not.

“Suppose, for instance,” continued Mr. Holiday, “that we had a barrel of phosphorus and a barrel of gunpowder, both open at the top, and were to set them on fire. The gunpowder would burn at once from the top to the bottom at a single flash, without any help from the outward air. The phosphorus would take fire on the top, and burn down gradually, as fast as the air could come to the flame. It would burn very fast and furiously, and I think it likely it would make, in all, a greater flame than the gunpowder. But then it would burn gradually and only as fast as it could get a supply of fresh air; so that if, while it was burning, men were to come and cover it all over with wet blankets, so as to keep away the air, it would smother it, and put it all out.”

“The water of the wet blankets would put it out,” said Rollo.

“No,” said his father; “it would be the same with any thing dry, if it would keep out the air. I presume, if a great quantity of dry sand was poured over it, it would put it out. But wet blankets or dry sand put over a barrel of gunpowder, even if we could have time to do it, would have no effect at all in stopping the burning; for the burning is not dependent upon the outward air at all; the combustion is entirely within itself; that is the essential peculiarity of gunpowder, on which all its powers depend.”

“I don’t see why it should burst open what it is confined in, after all,” said Rollo’s mother.

“Nor I,” said Rollo. “I should think it might burn up, without tearing things to pieces.”

“I don’t know myself,” replied Mr. Holiday, “exactly why it has such an expansive force. I’ll look in some book, when I get home, and see if I can find an explanation of it. But, at any rate, you see the difference in the manner of its burning. Now, there is wood, for example; it burns by degrees, as fast as the fresh air can come to it. When you put a stick of wood upon the fire, if it is dry and warm, and the fire is hot, first the outside takes fire. This burns because the air can get access to it. But the inside does not burn at all. If we were to take a stick off the fire, after it had been burning for half an hour, and saw it in two, we should find the middle as sound and solid as ever.”

“Should we sir?” said Rollo; “I should expect to find it all black coals.”

“No,” replied his father. “The blackness only extends in a very little distance; and the wood within is not burned any faster than the outside gets burned off out of the way, so as to let the air come to the inner layers, one after another.

“And there is a very curious contrivance in nature,” continued Mr. Holiday, “for supplying the fire all the time with fresh air.”

“What is it?” asked Rollo’s mother.

“Why, air is so constituted, that heat swells it, and makes it lighter; so that the air that is next to the outer layer of the wood, when the wood first begins to burn, becomes heated, and swells, and so, growing lighter, it immediately rises and goes out of the way, and a new supply of good, fresh air comes in to take its place. By the time that this is no longer good to promote the burning, it gets heated and rises; and so, there is a constant stream of hot air, that has passed through the fire, rising, and fresh air coming in to take its place. That is the reason, Rollo, why we have chimneys in a house. A chimney is nothing but an opening over a fire, so that the air can rise up through it as fast as it passes through the fire, and all the smoke and sparks pass up too.”

“I thought a chimney was only to let the smoke up,” said Rollo.

“No,” replied his father, “that is not all, by any means. If a fire made no smoke, it would still be almost as necessary as it is now to have a chimney. In fact, some fires do not make any smoke; some kinds of coal, dug out of the ground, do not make any smoke, and charcoal fires do not make any smoke; but still it is always necessary in such cases to have chimneys.

“Because,” he continued, “you must understand, that air gets changed in passing through a fire, so that it will not answer afterwards either to breathe, or to make a fire burn again; and therefore there must be some way for it to escape, not only out of the way of the fire, but also out of the room where people want to live and breathe. There is always such a stream of air rising up from every fire, great or small, even from a lamp.”

“Why, father, is a lamp a fire?” said Rollo.

“Certainly,” said his father, “it is a small fire made by burning oil on the top of a wick, and the hot air rises in a constant stream above it. So in a room, if there was no chimney over the fire, all the air that had passed through the fire, and become heated, would ascend to the top of the room. I saw the proof of this once, in a very singular manner.”

“How was it, sir?” said Rollo.

“It was one day when I was travelling. It was in the winter. I came to a hotel and was going up stairs to my room just before dinner. When I got to the head of the stairs, and was about going along the passage-way to my room, I saw, a little way before me, a door open, which led into another room; and there was a thick stream of white smoke, pouring out in the most beautiful manner, at the upper part of the door, and falling up to the ceiling.”

“Falling up!” said Rollo.

“Yes,” said his father. “It looked precisely like a little waterfall, falling up. There was no smoke at all coming out, except close to the top of the door; and, as soon as it got out, it went up to the ceiling of the entry, and from that it spread all around like water. It was very beautiful, but I had not time to stop to admire it, for I presumed that the room was on fire.”

“And did you cry fire?” said Rollo.

“No,” replied his father. “It is never best to call out for help, unless you are sure you need it. My room was very near. I remembered that my pitcher was full of water in my wash-stand. I ran and got the pitcher, and went into the room which the smoke was coming from. I saw a great blazing by the side of the fireplace.”

“And did you run and pour your water on?” said Rollo.

“No,” replied Mr. Holiday; “I didn’t pour it on, for in that case a great deal of it would have all run down upon the floor, and been wasted. I went up to the place, and put my hand into the pitcher, and began to sprinkle the water on as fast as I could, and it put the fire right out at once.”

“What was it that was burning?” asked Rollo.

“A basket of chips,” replied his father.

“A basket of chips!” repeated Rollo.

“Yes,” replied his father. “It seems that the man who occupied that room had gone out without taking down his fire, and he had left a small basket, with a few chips in the bottom of it, near the corner. Now, while he was gone, one of the sticks of wood had burned off, and the two ends outside of the andirons, not having been burned at all, were heavy; and so the ends of the stick fell over, one on one side and the other on the other. The stick which fell over towards the basket, threw a coal against it and set it on fire; and the basket, being very dry and thin, burned very fast. Scarcely any thing of the size makes a greater blaze, than a basket, for it is thin, and of such a form that the air can get to it on both sides.”

“That was a narrow escape,” said Rollo.

“Yes,” replied his father, “I think it was.”

“And I expect the landlord thanked you for saving his house from burning up,” said Rollo.

“On the contrary,” replied his father, “I had a scolding.”

“A scolding!” exclaimed Rollo.

“Yes,” replied his father; “I stepped out into the entry, and asked the chamber-maid who was there, if she would go and ask the landlord to come up into that room. When he came, I pointed to the wet and blackened ruins of the basket, and said,—

“‘We came very near having a fire, sir.’”

“And what did he say?” asked Rollo.

“Why, he thought that it was my room, and he was quite angry, and began to scold me for being so careless as to leave that basket so near the fire.”

“And what did you say?” asked Rollo.

“Nothing,” replied his father.

“Nothing!” exclaimed Rollo.

“No, I did not say any thing at all. I listened to hear all that he had to say, and then I went away to my room.”

“Why didn’t you tell him?” said Rollo.

“I thought I would let him find out in his own way,” replied his father.

“And did he find out?” said Rollo.

“Yes,” replied his father. “He came to me after dinner, and made a very humble apology. He told me that he was very sorry for what he had said, but that he supposed that that was my room.”

“And what did you tell him?” asked Rollo.

“I told him it was of no consequence,—and that a man who allowed himself to condemn before he made inquiry, must expect to fall into some mistakes.”

Under what circumstances did Rollo find himself taking a walk with his father and mother? What did Rollo’s father say was the peculiar and essential property of gunpowder? Which is more inflammable, phosphorus or gunpowder? How did Mr. Holiday illustrate this? What did Mr. Holiday say about the expansive force of burning gunpowder? By what process are fresh supplies of air furnished to fires? Why does the air which has once passed through the fire rise? What is a chimney for? Would a chimney be necessary if a fire made no smoke? Relate the incident which occurred to Mr. Holiday at the tavern. What example of prudence and presence of mind is furnished by this case? What example of hasty judgment? What example of patient forbearance?