Rollo's Philosophy. [Air]

"Do you think so?" said his father. "Then take the down, and lay it gently upon the hearth, before the fire, as near as you can."

Rollo did so. He had to take his hand away very quick, for it was quite hot there. The little tuft remained quietly upon the hearth where he placed it.

"There," said his father, "is not that a hotter place than it was over the lamp?"

"Yes, sir," said Rollo.

"Then, if it was heat that made it rise, why does not it rise now?"

Rollo could not tell.

"I will tell you how it was," said his father. "Heat makes air more expansive. When air is heated, it swells; when it is cool, it shrinks again. Now, if it swells, it becomes lighter, and so it is buoyed up by the heavier air around it; just as wood at the bottom of the sea would be buoyed up, and would rise to the surface of the water. Now, the heat of the lamp heats the air that is in the glass chimney, and swells it. This makes it lighter; and so the air around it, which is heavier, buoys it up, and it carries up the feather with it."

"No, the down, father," said Nathan.

"Yes, the down," said his father.

"Then it seems to me, after all," said Rollo, "that it is the heat which makes it rise."

"Yes," said his father, "it does, indirectly. It expands the air; that makes it lighter; then the heavy air around it buoys it up, and, when it goes up, it carries up the down. So that it is not strictly correct to say, that the heat carries it up. The heat sets in operation a train of causes and effects, the last of which results in carrying up the feather.

"Now," continued his father, "there is always a stream of air going up, wherever there is a lamp, or a fire, or heat, which heats the air in any way. The expanded air from a fire goes up chimney. The cool and heavy air in the room and out of doors crowds it up."

"The air out of doors?" said Rollo. "How can that crowd it up?"

"Why, it presses in through all the crevices and openings all around the room, and crowds the light air up the chimney. All the smoke is carried up too with it, and it comes pouring out at the top of the chimney all the time."

"You can see that the air presses in at all these crevices," continued Rollo's father, "by experiment."

"What experiment is it?" said Rollo; "let us try it."

"I will let Nathan try it," said his father, "and you may go with him and see the effect. First," he continued, "you see by the smoke, that the air really goes up the chimney; and I will show you that other air really crowds into the space, from other parts of the room."

So he took a lamp from the table,—not the study lamp; it was a common lamp,—and held it at various places in the opening of the fireplace, by the jambs and near the upper part; and Rollo and Nathan saw that the flame, in all cases, was turned in towards the chimney.

"Yes," said Rollo, "I see it is drawn in."

"No," said his father; "strictly speaking, it is not drawn in; it is pressed in, by the cool and heavy air of the room."

"I thought," said Rollo's mother, "that the chimney drew the air from the room into it."

"That is what is generally said," replied Mr. Holiday, "but it is not strictly true. The common idea is, that the hot air rises in the chimney, and so draws the air from the room to supply its place; but this is not so. In the first place, nothing can rise unless it is forced up. The lightest things have some weight, and would, if left to themselves, fall. The hottest and lightest air in a chimney would fall to the earth, if there was no cooler and heavier air around it, to force it to rise;—just as the lightest cork, which would rise very quick from the bottom of the sea, would fall back again very quick, if the water was not there.

"Remember, then, Nathan and Rollo, that, when a fire is built in a fireplace, so as to warm the air in the chimney, it makes this air not so heavy; and then the cool air all around it in the room and out of doors, presses in, and crowds under the light air, and makes it ascend."

"But, father," said Nathan, "you said I might perform an experiment."

"Very well, I am ready now. Take the lamp, and carry it around the room, and hold it opposite any little opening you can find."

"I can't find any little openings," said Nathan.

"O yes," said his father; "the key-hole of the door is a little opening, and there is a narrow crevice all around the door; and you will find little crevices around the windows. Now, hold the lamp opposite any of these, and you will see that the air presses in."

So Nathan went with the lamp, Rollo following him, and held the lamp opposite to the key-hole, and the crevices around the door and windows; only, when he came to the window, his father told him to be very careful not to set the curtain on fire.

Rollo wanted Nathan to let him try it once; and so Nathan gave him the lamp. He said he meant to make a crevice; and so he pushed up the window a very little way, and held the lamp opposite to the opening. The air pressed the flame in towards the room, in all cases.

"People commonly say, that it is drawn in," said his father, "but that is not strictly correct; it is really pressed in. There is no power of attraction, in the air that is in the room, to draw in the air that is out of doors, through the crevices; but the air that is out of doors, is so heavy, that it presses in, and crowds the warm and light air up the chimney.

"And now," said his father, "I cannot tell you anything more this evening; but, if you remember this, I will give you some further instruction another time."

"Well, sir," said Nathan, "only I wish you would tell me a little story, as you did last evening. Have not I been still?"

His father had noticed, that he had been very still and attentive, but did not think before, that it was in expectation of being rewarded with a story.

"Well," said his father, "I will tell you a story, or give you a little advice. How should you like a little advice?"

"Well, father, a little advice; just which you please."

"I advise you, then,—let me see,—what shall I advise you?—No, on the whole, I will tell you a story. Once there was a man, and he was a philosopher. He understood all that I have been explaining to you about the air being light when it was hot. So he got some very thin paper, and made a large paper bag. He cut the paper very curiously, and pasted it together at the edges in such a way, that the bag, when it was done, was round, like a ball; and it had a round opening at the bottom of it. In fact, it was a large paper ball."

"How large was it?" said Nathan.

"It was so large, that, when it was swelled out full, it would have been higher than your head."

"O, what a large ball!" said Nathan. "But what was it for?"

"Why, the man thought, as hot air is lighter than cool air, and floats up, that perhaps, if he could fill his paper ball with hot air, it would go up too."

"And did it?" said Nathan.

"Yes," said his father. "He filled it with hot air; and the hot air was so light, that it rose up and carried the paper ball with it."

"How did he get the hot air into it?" said Rollo.

"Why, he held it over a little fire, with the mouth down. Then the hot air from the fire went up into the ball, and swelled it out full."

"How high did it go?" said Nathan.

"O, it soared away," said his father, "away up into the air, very high; until at length it got cool, and then it came down."

"I should like to see such a ball as that," said Nathan.

"Such a ball as that is called a balloon," said his father.

"I wish I could see a balloon," said Nathan.

QUESTIONS

What is the important difference between air and water, which was explained in the last chapter, and mentioned in this? Does the air tend to expand again after it is compressed? What is this property of the air called? Is the air around us already condensed, or is it in its natural state? What causes it to be condensed? Suppose a thin glass vessel were to be filled with air, and another with water, and the air suddenly removed from the room around them; what would be the effects? What effect does heat have upon the expansibility of air? How may this effect be made to appear over a lamp? In a chimney? What was the story which Rollo's father told Nathan?

CHAPTER VII.

PHILOSOPHICAL DISCUSSION

Some time after this, Rollo, and Nathan, and James, were playing in the shed, one pleasant morning in the spring. They were building with sticks of wood, which they piled in various ways, so as to make houses. They took care not to pile the wood, in any case, higher than their shoulders, for Jonas had told them that, if they piled the wood higher than that, there would be danger of its falling down upon them.

After some time, Rollo went into the house a few minutes, and James and Nathan went to the open part of the shed, and began to look out of doors. The sun was shining pleasantly, but the ground was wet, being covered with streams and pools of water, and melting snow-banks.

"What a pleasant day!" said James. "I wish it was dry, so that we could go out better."

"I wish we could fly," said Nathan, "for it is very pleasant up in the air."

"I wish we had a balloon," said James. "If we had a balloon, we could go up in the air, easier than to fly."

"O James," said Nathan, "you could not get into a balloon if you had one."

"Why not?" said James.

"Because," said Nathan, "it would not be big enough."

"Why, Nathan," said James, "a balloon is bigger than this house."

"O James, it is not higher than my head."

"It is," said James, "I know it is. I have read about balloons bigger than a house."

"And my father," said Nathan, putting down his foot in a very positive air, "my father told me himself, that a balloon was about as high as my head."

The boys disputed some time longer upon the subject, and finally, when Rollo came out of the house, they both appealed to him very eagerly to settle the dispute.

"Isn't a balloon higher than Nathan's head?" said James.

"Is it as high as a house?" said Nathan.

"Why, I know," said Rollo, "that a man made a balloon once about as high as Nathan's head, because my father said so; but perhaps it was a little one."

"Yes," said James, "I know it must be a little one; for balloons are big enough for men to go up in them."

"O James," said Nathan, "I don't believe it. Besides, the fire would burn 'em."

"What fire?" said James.

"The fire they burn under the balloons, to make the air hot," said Nathan.

"I don't believe they have any fire," said James.

Just then Nathan, happening to look around, saw Jonas standing behind them; he had just come out of the house, and was going out to his work. Hearing the boys engaged in this dispute, he stopped to listen. The boys both appealed to Jonas.

Jonas heard all that they had to say, and then replied,—

"I cannot tell you much about going up in a balloon, but I can tell you something about getting along pleasantly down here upon the earth, which I think may be of service to you."

"What is it?" said James.

"Why, that you will neither of you get along very pleasantly until you can bear to have any body else mistaken, without contradicting them. James, you think Nathan is mistaken about the size of a balloon, do you?"

"Yes, I know he is," said James.

"Well," said Jonas, "now why not let him remain mistaken?"

"Why,—I don't know," said James.

"He isn't willing to be convinced, is he, that a balloon is as big as a house?"

"No," said James, "he is not."

"Then why don't you let him remain unconvinced? Why should you insist on setting him right, when he don't want to be set right?"

"And you, Nathan, suppose that James is mistaken, in thinking that the balloon is so big."

"Yes," said Nathan, "and that men can get into it, and go up in the air."

"Well, now, if he wants to believe that balloons are so big, why are you not willing that he should? Why should you insist upon it that he should know that they are smaller?"

"Because I know," said Nathan, very positively, "that they are small; and, besides, the paper would not be strong enough to bear a man."

"I did not ask you," said Jonas, "why you believed that men could not go up in balloons, but why you were so anxious to make James believe so. Why not let him be mistaken?"

"Why—because," said Nathan.

"You see, Nathan," continued Jonas, "the world is full of people that are continually mistaken; and if you go about trying to set them all right by disputing them, you'll have a hard row to hoe."

"A hard what?" said Nathan.

"A hard row to hoe," repeated Jonas. "It's never of any service to attempt to convince people that don't want to be convinced; especially if they are wrong."

"Especially if they are wrong!" repeated Rollo, in astonishment.

"Yes," replied Jonas. "The very worst time to argue with a boy, is when he is wrong, and does not want to be set right. It is a great deal harder to get along in argument with one who is right, than with one who is wrong; for the one who is wrong, disputes; the one who is right, reasons."

"Well, Jonas," said James, "which of us was disputing?"

"Both of you," said Jonas.

"Both of us," said James; "but you said that only the one who was wrong, disputed."

"Well," replied Jonas, "you were both wrong."

"Both wrong! O Jonas!" said James.

"Yes, both wrong," replied Jonas; and so saying, he was going away to his work.

"But stop a minute longer," said James, "and tell us how it is about the balloon; we want to know."

"O no," said Jonas, "you don't want to know; you want to conquer."

"What do you mean by that?" said Nathan.

"Why, you don't really wish to learn any thing; but you want to have me decide the case, because each of you hopes that I shall decide in his favor. You want the pleasure of a victory, not the pleasure of acquiring knowledge."

"No, Jonas," said Nathan, "we do really want to know."

"Well," said Jonas, "I can't stop now to tell you; perhaps I will this evening; but I advise you always, after this, not to contradict people, and dispute with them, when they say things that you don't believe. Do as the gentleman did, when the man said the moon was a fire."

"What did he do?" said Rollo.

"Why, he let him say it as much as he wanted to."

"Tell us all about it," said James.

"Well, then," said Jonas, "once there was a man, and he saw the moon coming up behind the trees, and thought it was a large house burning up. He went along a little way, and he met a vulgar fellow, riding in a carriage."

"Riding in a carriage!" repeated Rollo, astonished.

"Yes," said Jonas, "handsomely dressed. 'Sir,' said the man, 'see that great fire!'

"'It isn't a fire, you fool,' said the vulgar fellow; 'it's nothing but the moon.'

"'The moon! no it isn't,' said the man; 'it is a monstrous great fire. Don't you see how it blazes up?'

"'It is not a fire, I tell you,' said the vulgar fellow.

"'I tell you 'tis,' said the man.

"'You don't know any thing about it,' said the vulgar fellow.

"'And you don't know the moon from a house on fire,' said the man, and so passed on.

"A minute or two after this, he met a gentleman driving a team."

"A gentleman driving a team!" said James.

"Yes," said Jonas, "with a frock on. He was tired and weary, having driven all day. The man asked him if he did not see that house on fire.

"'Ah,' said the gentleman, 'I thought it was the moon.'

"'No,' said the man, 'it is a house on fire.'

"'Well,' said the gentleman, 'I am very sorry if it is. I hope they'll be able to put it out!'

"So saying, he started his team along, and bade the man good evening."

Jonas then, having finished his story, stepped out of the shed, and went along towards the barn; Nathan called out after him to say,—

"Well, Jonas, I don't understand how the gentleman came to be driving a team all day."

Jonas did not reply to this, but only began to laugh heartily, and to walk on. Nathan turned back into the shed, saying, he did not see what Jonas was laughing at.

The boys wanted very much to have the question about the balloon settled; and, after some further conversation on the subject, they concluded to go in and ask their mother. So they all three went in. Rollo proposed this plan, and he led the way into the house. He found his mother sitting in the parlor at her work.

"Well, boys," said she, "have you got tired of your play?"

"No, mother," said Rollo, "but we want to know about balloons: how big are they?"

"O, some of them," said she, "are very large."

"Ain't they as big as this house?" said James.

"Yes, I believe they have been made as big," said she.

"But, mother," said Nathan, "father told me, his very self, that they were no higher than my head."

"O no," said his mother; "he said that a man made one which was about as high as your head; but that was only a little one, for experiment. When they make large ones, for use, they are as high as this house."

"For use, mother? what use?" said Nathan.

"Men go up in them, don't they, aunt?" said James.

"Not in them, exactly," said his aunt. "They could not live in them, but they go up by means of them."

"How?" said Nathan.

"Why, they have a kind of basket, which hangs down below the balloon, and they get into that."

"I knew they could not get into the balloon," said Nathan.

"Then you have had a dispute about it," said his mother.

"Why,—yes," said Nathan, with hesitation, "we disputed a little."

"I am sorry to hear that," said his mother, "for disputing seldom does any good. The fact is, however, that men have often been carried up by balloons, but they never get into them. They could not live in them. They could not breathe the kind of air which balloons are filled with."

"It is hot air," said Nathan.

"No," said his mother, "the kind of balloon which your father told you of was filled with hot air; but the balloons which people generally use to go up with, are filled with another kind of air, which is very light when it is cool. They make an enormous bag of silk, and fill it with this light air, which they make in barrels; and then, when the bag is filled, it floats away above their heads, and pulls hard upon the fastening. There is a net all over it, and the ends of the net are drawn together below, and are fastened to the basket, or car, where the man is to sit. When it is all ready, the man gets into the car, and then they let go the fastenings, and away the great bag goes, and carries the man with it, away up into the air."

"And then how does he get down?" said Nathan.

"Why, he can open a hole in the bag, and let some of the light air out; and then he begins to come down slowly. If he comes down too fast, or if he finds that he is coming into the water, or down upon any dangerous place, there is a way by which he can make his balloon go up again."

"What way is it, aunt?" said James.

"Why, he has some bags of sand in his balloon," said his aunt; "and the balloon is made large enough to carry him and his sand-bags too. Then, if he finds that he is coming down too fast, he just pours out some of his sand, and that makes his car lighter; and so the balloon will carry him up again."

"That's a good plan," said Rollo.

"Yes," said his mother; "the reason why he takes sand is, because that will not hurt any body by falling upon them. If he should take stones, or any other heavy, solid things, and should drop them out of his car, they might possibly fall upon some body, and hurt them. So he takes sand in bags, and, when he wants to lighten his balloon, he just pours the sand out."

Rollo's mother then told the boys that there was a large book, which had several stories in it of men's going up in balloons, and that she would get it for them. So she left her work, and went out of the room; but in a few minutes she returned, bringing with her two very large, square books, with blue covers. One of them had pictures in it, and among the rest there were pictures of balloons. She opened the other book, and found the place where there was an account of balloons, and she showed the place to Rollo.

She told the boys that they had better go out in the kitchen, or into the shed, if it was warm enough, and read the account.

"You and James, Rollo," said she, "can read by turns, and let Nathan hear. Then, when the plates are referred to, you must look into the other book and find them."

"Yes," said Rollo, "we will; only, mother, if you would let us sit down here and read it—and then, if there is any thing which we cannot understand, you can tell us what it means."

"Very well," replied his mother, "you may sit down here upon the sofa."

So the boys sat down upon the sofa. They put Nathan between them, so that he might look over. Rollo and James took turns to read, and they continued reading about balloons for more than an hour. There was one story of a sheep, which a man carried up in his car, under a balloon, and then let him drop, from a great height, with a parachute over his head, to make him fall gently. And he did fall gently. He came down to the ground without being hurt at all.

QUESTIONS

How was the subject of balloons introduced into the conversation? What was Nathan's opinion about the possibility of being carried up by a balloon? What was the dispute about the size of balloons? What was Nathan's evidence? What was James's evidence? What did Jonas say when they appealed to him? What was the story that he related? Which of the boys did he finally say was wrong? Whom did the boys appeal to afterwards? What did Rollo's mother say about the size of balloons? How did she say that large balloons were filled? How can they make the balloon come down? How can they make it go up again, if they wish to do so?

CHAPTER VIII.

TASKS

A few days after this, there commenced a long storm of rain. Rollo and Nathan were glad to see it on one account, for their mother told them it would melt away the snow, and bring on the spring. The first day, they amused themselves pretty well, during their play hours, in the shed and in the garret; but on the second day, they began to be tired. Nathan came two or three times to his mother, to ask her what he should do; and Rollo himself, though, being older, his resources might naturally be expected to be greater, seemed to be out of employment.

At last, their mother proposed that they should come and sit down by her, and she would tell them something more about the air. "How should you like that, Rollo?" said she.

"Why, pretty well," said Rollo; but he spoke in an indifferent and hesitating manner, which showed that he did not feel much interest in his mother's proposal.

"I can't understand very well about the air," said Nathan.

Their mother, finding that the boys did not wish much to hear any conversation about the air, said nothing more about it just then, and Rollo and Nathan got some books, and began to read; but somehow or other, they did not find the books very interesting, and Rollo, after reading a little while, put down his book, and went to the window, saying that he wished it would stop raining. Nathan followed him, and they both looked out of the window with a weary and disconsolate air.

Their mother looked at them, and then said to herself, "They have not energy and decision enough to set themselves about something useful, and in fact I ought not to expect that they should have. I must supply the want, by my energy and decision."

Then she said aloud to Rollo and Nathan,—

"I want you, boys, to go up into the garret, and under the sky-light you will see a large box. Open this box, and you will find it filled with feathers. Select from these feathers three or four which are the most downy and soft about the stem, and bring them down to me."

"What are they for?" said Rollo.

"I will tell you," replied his mother, "when you have brought them to me."

So Rollo and Nathan went up into the garret, and brought the feathers. They carried them to their mother. She said that they would answer very well, and she laid them gently down upon the table.