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"It may be owing to the difference in the polish of the two blades, perhaps," replied Locke.

4. "Ah! that is an answer that don't go deeper than the surface," rejoined Bunker, humorously. "As good a thinker as you evidently are, you have not thought on this subject, I suspect. It took me a week, in all, I presume, of hard thinking, and making experiments at a blacksmith's shop, to discover the reason of this. It is not the polish for take two blades of equal polish, and the breath will disappear from one as much quicker than it does from the other, as the blade is better. It is because the material of the blade is more compact or less porous in one case than in the other.

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5. "In the first place, I ascertained that the steel was made more compact by being hammered and tempered, and that the better it was tempered the more compact it would become; the size of the pores being made, of course, less in the same proportion. Well, then, I saw the reason I was in search of, at once. For we know a wet sponge is longer in drying than a wet piece of green wood, because the pores of the first are bigger. A seasoned or shrunk piece of wood dries quicker than a green one, for the same

reason.

6. "Or you might bore a piece of wood with large gimlet-holes, and another with small ones, fill them both with water, and let them stand till the water evaporated, and the difference of time it would take to do this would make the case still more plain. So with the blades: the vapor lingers longest on the worst wrought and tempered one, because the pores, being larger, take in more of the wet particles, and require more time in drying."

7. "Your theory is at least a very ingenious one,” observed Locke, "and I am reminded by it of another of the natural phenomena, of the true explanation of which I have not been able to satisfy myself. It is this: what makes the earth freeze harder and deeper under a trodden

path than the untrodden earth around it? All that I have asked, say it is because the trodden earth is more compact. But is that reason a sufficient one?"

8. "No," said Bunker, "but I will tell you what the reason is, for I thought that out long ago. You know that, in the freezing months, much of the warmth we get is given out by the earth, from which, at intervals, if not constantly, to some extent, ascend the warm vapors to mingle with and moderate the cold atmosphere above.

9. "Now these ascending streams of warm air would be almost wholly obstructed by the compactness of a trodden path, and they would naturally divide at some distance below it, and pass up through the loose earth on each side, leaving the ground along the line of the path, to a great depth beneath it, a cold, dead mass, through which the frost would continue to penetrate, unchecked by the internal heat, which, in its unobstructed ascent on each side, would be continually checking or overcoming the frost in its action on the earth around.

10. "That, sir, is the true philosophy of the case, you may depend upon it. But we will now drop the discussion of these matters; for I am abundantly satisfied that you have not only knowledge enough, but that you can think for yourself. And now, sir, all I wish to know further about you is, whether you can teach others to think, which is half the battle with a teacher. But as I have had an eye on this point, while attending to the others, probably one experiment, which I will ask you to make on one of the boys here, will be all I shall want."

"Proceed, sir," said the other.

11. "Ay, sir," rejoined Bunker, turning to the open fireplace, in which the burning wood was sending up a column of smoke: "There, you see that smoke rising, don't you? Well, you and I know the reason why smoke goes upward, but my youngest boy does not, I think. Now take your own way, and see if you can make him understand it."

12. Locke, after a moment's reflection, and a glance round the room for something to serve for apparatus, took from a shelf, where he had espied a number of articles, the smallest of a set of cast-iron cart-boxes, as are usually termed the round hollow tubes in which the axle-tree of a carriage turns. Then selecting a tin cup that would just take in the box, and turning into the cup as much water as he judged, with the box, would fill it, he presented them separately to the boy, and said,

"There, my lad, tell me which of these is the heavier?" 13. "Why, the cart-box, to be sure," replied the boy, taking the cup, half-filled with water, in one hand, and the hollow iron in the other.

"Then you think this iron is heavier than as much water as would fill the place of it, do you?" resumed Locke.

"Why, yes, as heavy again, and more too-I know it is," promptly said the boy.

14. "Well, sir, now mark what I do," proceeded the former, dropping into the cup the iron box, through the hollow of which the water instantly rose to the brim of the vessel.

"There, you saw that water rise to the top of the cup, did you?"

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"Very well, what caused it to do so?"

15. "Why, I know well enough, if I could only think: why, it is because the iron is the heavier, and as it comes all around the water so it can't get away sideways, it is forced up."

"That is right; and now I want you to tell what makes that smoke rise up the chimney."

16. "Why, I guess," replied the boy, hesitating, "I guess, -I guess I don't know."

"Did you ever get up in a chair to look on some high shelf, so that your head was brought near the ceiling of a

heated room, in winter? and did you notice any difference between the air up there and the air near the floor?"

17 "Yes, I remember I have, and found the air up there as warm as mustard; and when I got down, and bent my head near the floor to pick up something, I found it as cold as could be."

"That is ever the case; but I wish you to tell me how the cold air always happens to settle down to the lower part of the room, while the warm air, somehow, at the same time, gets above."

18.Why, why, heavy things settle down, and the cold. air-yes, yes, that's it, I am sure-the cold air is heavier, and so settles down, and crowds up the warm air.”

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'Very good. You then understand that cold air is heavier than the heated air, as that iron is heavier than the water; so now we will go back to the main question— what makes the smoke go upwards?"

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19. 'Oh! I see now as plain as day; the cold air settles down all round, like the iron box, and drives up the hot air as fast as the fire heats it, in the middle, like the water; and so the hot air carries the smoke along up with it, just as feathers and things in a whirlwind. Well! I have found out what makes smoke go up-isn't it curious?" 20. "Done like a philosopher!" cried Bunker. "The thing is settled. I will grant that you are a teacher among a thousand. You can not only think yourself, but can teach others to think; so you may call the position yours as quick as you please."

DEFINITIONS.-2. In-tel-lěct'u-al, treating of the mind. 3. Těm'pered, brought to a proper degree of hardness. 4. Com-pǎet', closely and firmly united, solid, dense. 4. Pōr'oùs, full of pores or minute openings. 6. E-văp'o-rat-ed, passed off in vapor. 7. Inģēn'ious (pro. in-jen'yŭs), well formed, skillful. 7. Phe-nom'enon, whatever is presented to the eye. 8. In'ter-vals, spaces of time. 12. Ap-pa-rā'tus, utensils for performing experiments.

NOTE.-Locke Amsden is represented as a bright young student in search of a position as teacher of a district school in Vermont. Mr. Bunker, the “Examining Committee," is a queer, shrewd old farmer, who can neither read nor write, but by careful observation has picked up a large amount of valuable information. The story opens in the midst of the examination.

LXXIV. THE ISLE OF LONG AGO.

Benjamin Franklin Taylor (b. 1822, d. 1887) was born at Lowville N. Y. He graduated at Madison University, of which his father was president. In 1845 he published "Attractions of Language." For many years he was literary editor of the "Chicago Journal." Mr. Taylor wrote considerably for the magazines, was the author of many well known favorite pieces both in prose and verse, and achieved success as a lecturer.

1. Он, a wonderful stream is the river of Time,
As it runs through the realm of tears,
With a faultless rhythm and a musical rhyme,
And a boundless sweep and a surge sublime,
As it blends with the ocean of Years.

2. How the winters are drifting, like flakes of snow,
And the summers, like buds between;

And the year in the sheaf-so they come and they go,
On the river's breast, with its ebb and flow,
As it glides in the shadow and sheen.

3. There's a magical isle up the river of Time,
Where the softest of airs are playing;
There's a cloudless sky and a tropical clime,
And a song as sweet as a vesper chime,

And the Junes with the roses are staying.

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