"We took a tuft of down, tied to a thread, and held it in the cracks and places that the air came in at, to see which way it went. We held it at the window, and it blewinvery strong. At the bottom of the door, it blewinvery strong too; but at the top, it blewout, into the entry. So, when the entry is full of cold air, and this room full of warm, the cold air will press in and drive out some of the warm air, into the entry.Rollo."
"We took a tuft of down, tied to a thread, and held it in the cracks and places that the air came in at, to see which way it went. We held it at the window, and it blewinvery strong. At the bottom of the door, it blewinvery strong too; but at the top, it blewout, into the entry. So, when the entry is full of cold air, and this room full of warm, the cold air will press in and drive out some of the warm air, into the entry.
Rollo."
The other paper was also in Rollo's handwriting, and was as follows:—
"If the entry was full of water, and the parlor full of air, and the walls were water-tight, and you were to open the door between the two rooms, the water would flow into the parlor down below, and the airwould flow into the entry up above. We tried it with a tuft.Nathan."
"If the entry was full of water, and the parlor full of air, and the walls were water-tight, and you were to open the door between the two rooms, the water would flow into the parlor down below, and the airwould flow into the entry up above. We tried it with a tuft.
Nathan."
Why were Rollo and Nathan at first glad to see the rain? What did their mother say to herself on the second day, when she observed their weary and listless appearance? What did she at first direct them to do? How did she prepare the downy tuft? What experiments did they perform with it? Where did they find that the air came in which crowded the warm air up the chimney? What experiments did they perform when the door was opened? Which way did they find that the current of air was setting at the lower part of the door-way? Which way did the current set at the upper part of the door-way? What did Rollo write in his exercise? What was written in Nathan's exercise?
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Afterthe snow had all gone off, and the ground was dry, Jonas piled up a heap of stumps, roots, and decayed logs, in a field, not far from the brook, and one sunny afternoon he and Rollo went down to set the heaps on fire.
Jonas set one on fire, and then he told Rollo that he might set another on fire. After this, Jonas employed himself in gathering up sticks, bushes, roots, and other such things that lay scattered about the field, and putting them upon the fires, while Rollo amused himself in any way he pleased.
After a time, Rollo found, on the margin of the field, near the edge of a wood, an old stump, taller than he was, much decayed. There was a hole in the top. Rollo climbed up so that he could put a stick in, and run it down, to see how far down the hole extended.He found that it extended down very near to the bottom.
Then Rollo called out to Jonas, with a loud voice, saying,—
"Jonas, I have found a hollow stump here. It is hollow away down to the bottom. May I build a fire in it?"
"Yes," said Jonas, "if you can."
Rollo accordingly went to the nearest fire, and got a quantity of birch bark, which he had collected there to aid him in kindling his fires. He lighted one piece, and put it upon the end of a stick, and carried it to the stump, with the rest of the birch bark in the other hand.
Rollo then spent some time in fruitless attempts to make some lighted birch bark go down into the stump, and burn there. He succeeded very well in getting pieces completely on fire; but, after they were dropped into the hole, they would not burn. Rollo could not think what the reason could be.
At last he called Jonas to come and help him set the stump on fire.
Jonas said that he did not think that it could be set on fire.
"'Jonas, I have found a hollow stump here,' said Rollo, calling with a loud voice."—Page 122.
"Why not?" said Rollo.
"Because," said Jonas, "it is so wet."
"Yes, but, Jonas," replied Rollo, "your brush heaps burn, and why should not this stump?"
"Because," said Jonas, "the stump is more solid, and the water soaks into it more in the winter and early in the spring; and it takes it much longer to dry, than it does brush and small roots, which lie open and exposed to the air."
"Well, then," replied Rollo, "why does not my birch bark burn? that is dry; but as soon as I drop it down into the stump, it goes out."
Jonas looked into the stump, and down around the bottom of it, and said,—
"Because there is no air."
"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 thebottom, 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, andput 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 makesthe 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 amusedhimself 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."
"No," replied Jonas, "it is not the smoke. I can prove that it is not."
So Jonas came up to the fire where Rollo was standing, and pointed out to Rollo a place, over a hot part of it, where there was no smoke, because the fire under it burned clear, being nearly reduced to coals. He told Rollo to hold his blazing bark there. Rollo did so, and found that it was extinguished at once, and as completely, as it had been before, when he had held it in a dense smoke.
"Yes," said Rollo, "it isn't the smoke. But perhaps it is because it is so hot."
"No," said Jonas, "it isn't that. It is a difference in the air. They sometimes collectdifferent kinds of air in glass jars, and then let a candle down in, and see whether it will go out."
"And will it go out?" said Rollo.
"That depends upon what kind of air it is," said Jonas. "They all look clear, just as if there was nothing in the jars; but when you let a candle down in, in some it burns just the same as before; in some it burns brighter; and in some it goes out."
"In what kinds does it go out?" asked Rollo.
"I only know of one kind," said Jonas, "and that is a kind that comes of itself in mines, and wells, and other places."
"What is the name of it?" asked Rollo.
"Why, the people in the mines call it choke damp; but I believe it has got another name besides."
"What do they call it choke damp for?" said Rollo.
"Because," said Jonas, "if the miners get into it and breathe it, it kills them. It is not any better to breathe than it is to make fires burn."
"I wish I could see some choke damp," said Rollo.
"O, you can't see it at all," said Jonas, "if it was right before you, any more than you can see common air. If a well or a mine is full of it, they cannot find it out by looking down."
"How do they find it out?" said Rollo.
"Why, they let a candle down," replied Jonas.
"And will the candle go out?" asked Rollo.
"Yes," said Jonas, "if there is choke damp in the well. Sometimes they make a little of it in a tumbler or a jar upon the table, and so let a little flame down into it, and it goes out immediately."
"I wish we could make some," said Rollo. "Do you know how they make it?"
"No," said Jonas; "but I believe it is pretty easy to do it, if we only knew how."
"I will ask my father," said Rollo; "perhaps he will know."
This conversation took place when Jonas and Rollo were about the fires; but now the fires had pretty nearly burnt out, and they prepared to go home.
That evening, just about sunset, Rollo went out behind the house, and found Jonasraking off the yard. The spring was fast coming on, and the grass was beginning to look a little green; and Jonas said he wanted to get off all the sticks, chips, and straws, so that the yard would present a surface of smooth and uniform green. Rollo told him that he had found out how to make choke damp.
"Did your father tell you?" said Jonas.
"No," replied Rollo.
"Who did tell you, then?" said Jonas.
"Guess," answered Rollo.
"Your mother," said Jonas.
"No," answered Rollo.
"Then I can't tell," said Jonas.
"It was Miss Mary," replied Rollo. "I met her in the road to-day, and I asked her."
"And how is it?" asked Jonas.
"Why, we make it with chalk and vinegar," said Rollo. "We pound up a little chalk, and put it in the bottom of a tumbler. Then we pour some vinegar over it. The vinegar takes the choke damp out of the chalk, and Miss Mary says it will come up in little bubbles. She says we can lay a paper over the top loosely,—she said loosely, but I think it ought to be tight."
"Why?" asked Jonas.
"So as to keep the choke damp from coming out," replied Rollo.
"No," said Jonas. "I understand why she said you must put it on loosely; that's to let the common air out."
"What common air?" said Rollo.
"Why, the air that was in the tumbler before," replied Jonas. "You see that, as fast as the choke damp comes up, it drives the common air out of the top of the tumbler; and so you must put the paper on loosely, and let it go out."
That evening Jonas and Rollo tried the experiment. First they put about two teaspoonfuls of chalk into the tumbler. Then they poured in the vinegar. It immediately began to foam.
"Ah," said Rollo, "that's the effervescence."
"The what?" said Dorothy; for they were making this experiment upon the kitchen table, and Dorothy was standing by, looking on with great interest.
"Theeffervescence," said Rollo. "Miss Mary said there would be an effervescence, which would be occasioned by the littlebubbles of choke damp, coming up from the chalk."
"Poh!" said Dorothy; "it's nothing but a little frothing."
"It isn't frothing," said Rollo, very seriously; "it isn't frothing, it is effervescence. Don't you think Miss Mary knows?"
"Jonas," said Rollo again after a short pause, "how many of these little bubbles will it take, do you think, to fill the tumbler full of choke damp?"
"I don't know," replied Jonas; "we will wait a little while, and then try it."
"There, now, Jonas," said Rollo, "we have not got any candle."
"O, I will roll up a piece of paper, and set the end on fire, and then dip it down into the tumbler, and that will do just as well."
"What are you going to do that for?" said Dorothy.
"Why, to see it go out," said Rollo.
"It won't go out, unless you put it away down into the vinegar," said Dorothy.
"Yes it will," said Rollo; "we are only going to dip it down a little way, just into the choke damp, and it will go out."
"It won't go out, child," said Dorothy. "There's nothing to put it out."
"Well, you'll see. Won't it go out, Jonas?"
"I don't know," said Jonas.
"Don't know?" said Rollo. "Why, you told me that choke damp would put out a blaze."
"Yes," said Jonas, "I am sure of that; but there are a great many ways of failing in trying experiments."
"Well," said Rollo, "that may be; but this will not fail, I know, for I can see the little bubbles of choke damp coming up. There are millions of them."
By this time Jonas thought that the tumbler was filled with the gas, which was rising from the chalk and vinegar. So he rolled up a piece of paper, and set the end on fire, and, when it was well burning, he plunged the end of it into the tumbler. To Rollo's great disappointment and mortification, it continued to burn about as much as ever. The flame crept rapidly up the paper, and Jonas had soon to run with it across the floor and throw it into the fire, to avoid burning his fingers. Dorothy laughed aloud; Jonas smiled; andas for Rollo, he looked disappointed and vexed, and appeared to be overwhelmed with chagrin.
Dorothy continued to laugh at them, while Jonas went to the pump and washed out the tumbler. At length she said,—
"But come, Rollo, don't be so disconsolate. You look as if you had swallowed all the choke damp."
"Yes, Rollo," said Jonas, "we must keep good-natured, even if our experiments do fail."
"Well," said Rollo, "I mean to ask Miss Mary again, and then we can do it, I know."
Rollo accordingly went, the next day, to ask Miss Mary about the cause of the failure. Miss Mary said that she could not think of any thing which was likely to be the cause, unless it was that they put too large a flame into the tumbler.
"Well," replied Rollo, "and what harm would that do? Won't the choke damp put out a large flame?"
"Yes," replied Miss Mary, "if it only fairly surrounds and covers it; but, then, if you put a large flame into a tumbler, it makesthe first instant, a great current of air, and so the choke damp might be blown out, and common air get in, and so keep the paper burning."
"How does it make a current of air?" asked Rollo.
"Why, the heat of the flame, when you first put the paper in," replied Miss Mary, "makes the air that is above it lighter; and the common air all around crowds in under it, in buoying it up; and by that means, if the flame is too large, common air is carried into the tumbler. You ought to make a very small flame, if you leave the top of the tumbler open."
"How can we make a small flame?" said Rollo.
"One good way," replied Miss Mary, "is to roll up some paper into a very small roll. I will show you how."
So Miss Mary took a piece of paper, and cut it into the proper shape with her scissors, and then rolled it up into a long and very slender roll; one end of it was not much larger than a large knitting-needle. She gave this to Rollo, and told him that, if he tried the experiment again, he must light the smallend, and it would make a flame not so big as a pea.
Rollo explained to Jonas what Miss Mary had said, and they resolved on attempting the experiment again that evening. And they did so. Dorothy stood by watching the process, as she had done the evening before, but Rollo did not assert so confidently and positively what the result would be. He had learned moderation by the experience of the night before.
When all was ready, Jonas lighted the end of the slender roll in the lamp, and plunged it carefully into the tumbler. It went out immediately.
"There!" said Rollo, clapping his hands, "it goes out."
"Why, it is only because the wind blew it out."
"No, Dorothy," said Rollo, "there isn't any wind in the tumbler."
"Yes," replied Dorothy, "when you push it down, it makes a little wind, just enough to blow it out."
"Get another tumbler," said Jonas, "and let us see."
So Dorothy brought another tumbler, andJonas put the burning end of the paper down into it, with about as rapid a motion as that with which he had put it before into the tumbler he had at first. The paper continued to burn.
"There," said he to Dorothy, "when I put it down into common air, it burns on the same as ever; so it can't be that the wind puts it out." Jonas repeated the experiment a number of times; the effect was always the same. Whenever he put it into the tumbler of common air, it burned on without any change; but whenever he put it into the choke damp, it immediately went out. Even Dorothy was satisfied that there was a difference in the kind of air contained in the two tumblers.
That evening, when Rollo gave his mother a full account of their attempts,—describing particularly their failure at first, and their subsequent successes,—his mother seemed much interested. When he had finished, she said,—
"Well, Rollo, I don't see but that you have learned two lessons in philosophy."
"Two lessons?" said Rollo.
"Yes," replied his mother. "The first is,that fire will not burn in choke damp; and the second is, that it requires nice attention and care to verify philosophical truths by experiment."
"Yes," said Rollo, "we missed the first time, just because we had too big a paper."
Why did Jonas suppose that the stump would not burn? What was Rollo's first mode of setting it on fire? How did it succeed? What did Jonas do with his axe, when he came? What was the object of this? What did he say was necessary to make fires burn? What did Rollo at first think was the reason why the bark went out when held over the fire? What did he next think was the reason? How did Jonas say that different kinds of airs were prepared? In what places did he say that choke damp was naturally produced? How did they attempt to prepare some of this gas? Did they succeed in preparing it? Did they succeed in their experiment at first? What was the cause of the failure?
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Oneevening, after tea, when Rollo was a pretty big boy, he came and began to climb up into his father's lap. When he had climbed up, he took his place astride of his father's knee, as if he were riding a horse. His little brother Nathan came up and stood near, wanting to get up too, only there was not room. His cousin James was there, that evening, on a visit. He sat upon a cricket before the fire, and his mother was at the table doing some sort of work.
"O dear me!" said Rollo's father, imitating the tone in which Rollo sometimes uttered that exclamation.
"What, sir?" said Rollo.
"Why, I should like very well to hold you in my lap," said his father, "if it was not for the great mighty earth, down below us."
"How?" said Rollo. He did not know what his father meant.
"Why, when you are upon my knee, the earth, the ponderous earth, pulls you down hard and heavy upon it." So saying, he put his hands upon Rollo's shoulders, and crowded them down, by way of showing him how the earth acted upon him. "It pulls," he continued, "with a strong and steady pull, all the time; and so makes you a very heavy weight."
"Is that what makes weight?" said Rollo.
"Yes," said his father. "So, if I had a monstrous stone to move, and if I thought the earth would listen to me, and let go its hold, I might make a speech to it thus:—
"'O earth, thou vast and ponderous ball, please to relax thy hold, for a few minutes, upon this stone, and leave it free to move; and then Rollo can tie a string to it, and move it easily along to the place where I want it to lie; then thou mayst seize it again with thy mighty attraction, and hold it down as firmly as thou wilt.'"
"O father!" exclaimed Rollo; Nathan and James laughed, and Rollo's mother looked up from her work to listen to this strange apostrophe.
"It would seem," continued his father, in a pompous tone, as if still addressing the earth—"it would seem, most mighty planet, a very easy thing for thee to release this single stone, for a few minutes, from the grasp with which thou holdest all things down upon thy surface. And by it I shall gain much, while thou wilt lose nothing; for, if thou wilt not willingly give up the stone, I must get three or four yoke of strong oxen, and, by main force, pull it away."
"Is that what makes everything heavy?" said Rollo.
"Yes," said his father, answering now in his natural tone; "the attraction of the earth is what makes everything heavy, and holds it down."
"And could we move a monstrous great stone," said Rollo, "as light as a feather?"
"No," said his father, "it would not move along quick and light, like a feather. You could not move it quick. Suppose, for instance, you had two boats, floating upon the water, of the same size; one made very light indeed, of something very thin, like paper, and empty; and the other made of wood, and loaded with iron as heavily as itwould bear. Now, they would both be supported upon the water, so that their weight would be neutralized; and yet they would move very differently. You could push the light one about easily, anywhere, but the heavy one would move very slowly. You would not have to push very hard upon it, but you would have to pushfor some time, to set it in motion; and then it would be hard to stop it. This is called itsinertia."
"Yes," said Rollo, "it would go harder against the bank."
"The reason is," continued his father, "that the heavy boat contains a great many more particles of matter than the light one, and they have all got to be put in motion. So it requires greater effort, or the same effort must be continued a longer time.
"For instance, if we suppose that the light boat has one million of particles of matter, the heavy one would have, perhaps, twenty millions. Of course the effect of the pushing has to be divided among twenty times as many particles, and of course will only carry them one twentieth part as far; so that the bodies that are now large and heavy, would only move slowly, thoughthey would moveeasily, if the attraction of the earth were to cease.
"There is another way to illustrate it," he continued. "Suppose there was a large mass of lead, as big as a load of hay, hanging by a chain; and also a great puff of feathers, or a balloon of the same size, hanging in the same way. Now, if they were both suspended freely, they would both move easily, for their weight would be supported by the chain; but the heavy one would move very slowly. Nathan could move it, but he could only move it slowly and a little way."
"I should not think that he could move it but very little," said Rollo.
"No, he could not; because you see that, in that way of suspending anything, the moment that it begins to move, it begins to swing off and to rise; so that it cannot be moved at all without beinglifteda little. And the more it is moved, the higher it is lifted, so that it would take a great force to move it far away from the centre, where it was hanging. But we can hang it in a way to avoid that difficulty."
"How, sir?" said Rollo.
Rollo seemed to be very much interested in this conversation. He had dismounted from his father's knee, and stood by his side, listening eagerly. His mother, too, was paying close attention. As for Nathan, he sat still; though it is not by any means certain that he understood it very well.
"Let us suppose," said his father, "that the mass of lead, as big as a load of hay, is fastened to one end of a stick of timber."
"That would not be strong enough to hold it," said Rollo.
"Well, then, to a beam of iron, as large as a stick of timber," rejoined his father.
"O," said James, "you could not get such a big bar of iron."
"No," replied his father, "only an imaginary one; and that will be just as good as any. Now, suppose the great mass of lead is fastened to one end of this bar, and another one, just like it, to the other end, to balance it. Now, suppose that the lower end of the great chain is secured around the middle of the iron beam, and the upper end to be fastened to some strong support up in the air. Now, we can move the mass of lead without having to lift it at all; for, if we push againstit, and make it move, it will move round and round, without rising at all, as it did before, when it was hung up directly by the chain."
Rollo's father then went on to explain to them that, in such a case as this, the weight of the two masses of lead would not prevent their moving easily, for they would exactly balance each other. A little child would be able to move them; but still they would move exceedingly slow at first, and it would be hard to stop them, when they were in motion. So, he said, if the earth should cease to attract and draw down any great, heavy body, like a large stone, for example, the smallest child could lift it, though it would come up slowly, just as a very heavy body would move, if it was suspended by a string, or was afloat upon the water.
"And so," said Rollo, "if the earth should not attract us, could we push ourselves right up off from the ground?"
"Yes," said his father, "most undoubtedly."
"What, and go about anywhere in the air?"
"Certainly."
Rollo began to laugh aloud at this idea, and looked very much interested and pleased.
"O, then I wish there was no gravitation," said Rollo; "I do, really."
"But, then," continued his father, "if you should get up into the air, you could not get down again."
"Why not?" said Nathan, beginning to look a little concerned.
"Unless," said his father, "you had something above you, to push against, so as to push yourselves down. You would be just like a boy in a boat, off from the shore, and without any paddle or pole. He could not get back again."
"We might tie a rope to something," said James, "before we went up, and so pull ourselves down."
"Yes, that you might do."
"And could not we flap our hands, like a bird, and so fly a little?"
"Perhaps you could," said his father.
Here the children all began to flap their hands, like young birds trying to fly; and Rollo said again, he wished, with all his heart, there was no gravitation; "for then," said he, "we should have strength enough to fly."
"That would lead to serious consequences," said his father.
"What consequences?" said James.
"Much more serious than you would suppose."
"Tell us what they would be, uncle," said James.
"O, I know," said Rollo; "you could not stand up straight without gravitation."
"O, we could, couldn't we, father?" said Nathan.
"What makes you think, Rollo," said his father, without replying to James's question—"what makes you think that we could not stand up straight without gravitation?"
"Why, you see," said Rollo.—Here he paused, and looked confused, and did not know what to say. He had an indistinct recollection of having read something about it in some book; but he could not tell what.
"I don't see what should prevent any body's standing up straight, if the attraction of the earth should cease; in fact, if it made any difference, it would be rather easier to stand up straight."
Here Rollo looked rather foolish, but he did not reply. The truth is, like almost allother children, who take an interest in reading, he was sometimes a little vain of his knowledge; and in this case, instead of listening attentively, and endeavoring to learn something new from his father's explanations, he seems to have thought it a good plan for him to help him elucidate the subject to James and Nathan. He exchanged the character of learner for teacher too soon.
"Well, uncle," said James, "what would be the consequence if gravitation should cease?"
"Why, in the first place," said Rollo's father, "all the streams in the world would stop running."
"The streams!" said Rollo, astonished.
"Yes," said his father, "every river, brook, and rill. The reason why the streams flow is, that the earth attracts the water from the mountains and hills, down into the valleys and towards the sea."
"Well, sir, what else?" said Rollo.
"Why, there would never be any more rain."
"No more rain!" exclaimed all the children.
"No," he replied. "The drops of rain fallonly because the earth draws them down by its attraction; and, of course, if this attraction should cease, they would remain where they are."
The children were musing a minute upon these strange effects, when Rollo asked if anything else would happen.
"Why, yes," said his father, "worse disasters than these; but I do not know whether you would understand them, if I should explain them."
"O, try," said Rollo; "I think we shall understand."
"Well, let me think," said his father. "You have noticed how a chaise wheel, on a muddy road, in a wet day, holds the mud upon it, until when it is going very swiftly down a hill, and then the mud flies off in all directions."
"Yes, sir," said all the children.
"And if the mud did not stick to the wheel pretty tight, it would be thrown off at all times, even when the wheel was going slow. You understand this."
"Yes, sir."
"Well, now, this whole earth, you all know, is whirling around through space, and movingon also around the sun. And all the loose things upon the surface would be thrown off at once, if they were not held to it by a strong attraction. If this attraction were to cease suddenly,—whisk!—away we should all go in an instant—rocks, houses, men, animals, all in confusion."
"O father!" exclaimed Rollo; "where should we go to,—off into the air?"
"Not exactly into the air, for the air would all fly off, and be dissipated too; we should fly off into the sky somewhere, some in one direction, and some in another. You'd be a thousand miles off from the earth, almost before you would know it."
"Would it kill us, father?" said Nathan.
"Yes," said his father. "I don't know that there would be any shock that would hurt us, but we should have no air to breathe, and it would be dark and dismal."
"Dark?" said Rollo. "There would be the sun."
"Yes," said his father, "there would be the sun; and the sun would look bright enough when you looked directly towards it, but there would be no general light about you, unless there was air."
The children all paused to reflect upon the strange results which their father had told them would ensue from a suspension of the earth's attractive force. Rollo began to think that he had been too hasty in his wish that there was no gravitation.
"But, father," said he, "the houses would not go off, certainly;—only the loose things would go."
"Very well; houses are loose."
"O father! they are fastened down."
"How are they fastened down?" asked his father.
"O, they are nailed—and,"
"Not nailed to the ground, certainly," said his father.
"No," said Rollo, laughing; "but then they are built with great stones and mortar."
"Yes, but there is no mortar under the lowest stones. The foundations are simply laid upon the ground."
"Well," rejoined Rollo, "I thought they were fastened somehow or other."
"No," said his father; "they dig the cellar, and only just lay the foundations upon the ground, without any fastening. The earth holds them in place."
"Well, father," said Rollo, "that is what I meant, when I said we could not stand up straight. I meant the houses. I read in a book that houses would be blown away, if the gravitation did not hold them down."
Here Rollo's father had a hearty laugh; and he told Rollo that he thought that was rather wide shooting. Rollo wanted to know what he was laughing at; and Nathan asked him what he meant by wide shooting.
"Why," said he, "Rollo, you undertook to explain to us, from your stores of knowledge, what the effects of a suspension of gravitation would be; and, in attempting to tell that houses would be in danger of being blown away, you came no nearer than to tell us that boys could not stand up straight; and that is what I call pretty wide shooting."
So saying, he rose from his seat, and walked away, appearing to be very much amused. James laughed too, and even Rollo could not help smiling at the ridiculous figure which his display of his learning made. As for Nathan, he continued to look grave; and said he did not see that it was any shooting at all.
After a short pause, Rollo's mother said, "So you see, children, the cause of all the pressure, both of air and of water, and all the effects produced by them, are the results of their gravitation towards the earth."
"Yes," said Rollo, "I believe I understand it now."
After this, Rollo took James and Nathan out into the yard, to see if some beans had come up, which he had been planting in a sunny corner of the garden the day before.
What was Mr. Holiday's apostrophe to the earth? What is the cause of weight? Why did the boys wish that there was no gravitation? What was the first evil consequence which their father said would ensue, if there was no gravitation? What was the second evil consequence? What did their mother say after the conversation with their father was closed?
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Rollo's dam, which he had made when he was studying the philosophy of water, and which was at first undermined by the pressure of the water, was afterwards carried away by its momentum. Rollo learned, at that time, that water moving rapidly had a great momentum; and about this time he had an opportunity of learning that air, when in motion, had a momentum too, capable of producing very powerful effects. The circumstances of the case were as follows:—
One morning, towards the latter part of March, Jonas, being out in the barn, observed some indications that the roof wanted repairs. It had been strained and weakened by the heavy snows in the winter. He reported the fact to Rollo's father, who said that he might go, the next day, and get the carpenter to come and repair it. The carpenterlived ten miles distant, near the shore of a long pond.
When Rollo heard of this proposed expedition, he wanted to go too; and his father gave him permission. Jonas was going in the wagon. He told Rollo, the evening before, that he meant to set out at six o'clock.
"But suppose it looks like a storm," said Rollo.
"Then there will be more need of going," said Jonas; "for if the equinoctial storm comes on before the roof is strengthened, it may get carried away."
"What is the equinoctial storm?" said Rollo.
"O, it is a great storm, which comes generally about this time of year. I shouldn't wonder if it should come on to-morrow. But it may not come for a week; and so I hope we shall have time to get the roof mended first."
"Does it look like a storm to-night?" said Rollo.
"No, not much," replied Jonas. "It is a little hazy in the south-west. However, if it looks like a storm in the morning, you need not go, unless you choose; though I shall."
"I wish you'd wait till the storm is over," said Rollo.
"No," said Jonas, "I had rather go in the storm than not."
"Why?" said Rollo.
"Because," said Jonas, "I like to be out in storms. Sometimes it is very grand."
The next morning, when Rollo awoke, he found that it was light, but not yet sunrise. He arose, and looked out of the window to see if it was pleasant. The sky was somewhat overcast, but there was a little blue to be seen, and Rollo thought that it would be pleasant. He heard a noise in the barn-yard, and, looking in that direction, he saw Jonas just leading the horse out of the stable. So he dressed himself soon, and went down.
When he got ready, he went down into the yard, and found that Jonas had got the horse harnessed, and everything prepared. There was a little bag of oats in the back part of the wagon, and also a tin pail, with a cover, which contained a luncheon. Jonas fastened the horse to a post, and said,—
"Now, Rollo, we'll go in and get some breakfast."
"I thought that luncheon was for breakfast," said Rollo.
"No," said Jonas, "that is for dinner."
"Shall we be gone all the day?" said Rollo.
"We may be gone till after dinner," said Jonas, "and so I thought I would be sure."
The two boys went into the house, and there they found that Dorothy had got some breakfast ready for them upon the kitchen table. After eating their breakfast, they got into the wagon, and set out. Jonas first put in a large umbrella. Just as they were driving out of the yard, the first beams of the morning sun shone in under the branches of a great tree in the yard, and brightened up the tips of the horses' ears and the boys' faces. At the same time, a rude gust of wind came around the corners of the house, and slammed to the gate of the front yard.
"It's going to be pleasant," said Rollo; "the sun is coming out."
"I'm not very sure of that," said Jonas; "the wind is rising."
"We start just at sunrise," said Rollo.
"Yes," replied Jonas, "the sun always rises at six o'clock at this time of the year."
The boys rode along for about three hours, before they came to the carpenter's. They were obliged to travel very slow, for the roads were not good. It is true that the snow was all gone, and the frost was nearly out of the ground; but there were many deep ruts, and in some places it was muddy. The sun went into a cloud soon after they set out, and it continued overcast all the morning. There was some wind too, but, as it was behind them, and as the road lay through woods and among sheltered hills, they did not observe it much. Jonas said that there was a storm coming on, but he thought it was coming slowly.
They arrived at length at the pond. There was a little village there, upon the shore of the pond. The reason why there happened to be a village there, was this: A stream of water, which came down from among the mountains, emptied into the pond here, and, very near where it emptied, it fell over a ledge of rocks, making a waterfall, where the people had built some mills. Now, where there are mills, there must generally be a blacksmith's shop, to mend the iron work when it gets broken, and to repairtools. There is often a tavern, also, for the people who come to the mills; and then there is generally a store or two; for wherever people have to come together, for any business, there is a good place to open a store, to sell them what they want to buy. Thus there was a little village about these mills, which was generally called the Mill village.
Jonas inquired where the carpenter lived, and then drove directly to his house. He found that he was not at home. He had gone across the pond, to mend a bridge, which had been in part carried away by the floods made when the snow went off. Rollo sat in the wagon in the yard by the side of the carpenter's house, while Jonas stood at the door, making inquiries and getting this information.
"If you want to see him very much," said the carpenter's wife, "I presume you can get a boat down in the village, and go across the pond."
"How far is he from the other side of the pond?"
"O, close by the upper landing," said she;"not a quarter of a mile from the shore, right up the road."
Jonas thanked the woman for her information, and got into the wagon.
"Let us get a boat and go over, Jonas," said Rollo, as they were turning the wagon round.
"I should," said Jonas, "if there was not such a threatening of a storm."
"It does not blow much," said Rollo.
"No," said Jonas, "not much now, but the wind may rise before we get back. However, we'll go and see if we can get a boat."