Chapter XXII: A Boy's Bargain (2)

When people go up rapidly in a balloon or climb very high mountains, they are troubled by a ringing noise and a feeling of great pressure in the ears and head, and by palpitation of the heart, bleeding at the nose, and fainting. These unpleasant and often dangerous symptoms are caused by the expansion of the air inside their bodies. In ascending very high mountains it is necessary to go very slowly and to stop very often, to give time for some of the expanded air to escape, and equalize the pressure again. Now, many birds, the condor, for example, fly over the tops of the highest mountains, and nearly all birds, either occasionally or habitually, ascend to very great altitudes, and, unless there were some plan for regulating the pressure of the air inside their bodies, they would suffer great inconvenience and even pain and danger. But they are provided with an arrangement by which the air within them can escape easily as it expands and thus keep the pressure within just equal to that outside, so that they can ascend and descend as rapidly as they wish, without feeling the least inconvenience. In the body of the bird there are several large bags, like the lungs, called air-chambers; many of their bones are hollow, and others are pierced with long winding tubes called air-tubes. All these air-chambers and air-tubes are connected with the lungs so that air can pass into and out of them at each breath. The connection between these chambers and the lungs is so complete that a wounded hawk can breathe through a broken wing almost as well as through its mouth. When a bird mounts upward, the air inside its body gradually expands, but the bird does not feel any inconvenience; for, at each breath, part of the air passes from the air-chambers into the lungs, so that the pressure on the inside does not become greater than that on the outside.

I could easily fill the whole of this chapter with an account of the different ways in which the body of a bird is fitted for life in the air, but we have room to examine only one of these,--the way in which the wing is adapted to its use.

Did you ever look at a bird's wing carefully, and try to find out from it the way in which it is used? People usually suppose, either that a bird flies because it is lighter than the air, like a balloon, or that it rows itself along as a boat is rowed through the water. Neither of these suppositions is true. A bird is not lighter than the air, and does not float; for when a bird is shot on the wing it falls to the ground just as quickly as a squirrel. On the contrary, a bird flies by its own weight, and could not fly at all if it were not heavier than the air.

You know that when you move a large, flat surface rapidly through the air, it meets with considerable resistance. A bird's wing is so large, and is moved so rapidly, that the resistance of the air is enough to raise the bird a short distance each time the wings are flapped downward; but after each down-flap there must be an up-flap, and the air resists this just as it does the down-flap; so, unless there were some arrangement to prevent it, the bird would drive itself down each time it raised its wings, just as far as it had raised itself by the down-stroke before, so that it would never get into the air at all. To meet this difficulty, the wing is so shaped that it is concave or hollow upon its lower surface, so that it gathers the air together and prevents it from escaping; while the upper surface is convex or bulging, so that the air slides off from it when the wing is moved upward. If you have ever been caught in a sudden squall of wind with an open umbrella, you will easily understand how great a difference in resisting power this difference in the shape of the two sides of the wing will make. As long as you can keep the bulging side of the umbrella pointed toward the wind, you find no difficulty in holding it; but if the wind strikes the hollow under-side of the umbrella, it pulls so violently that, unless you are able to turn around and face the wind, the chances are that the umbrella will either be pulled away from you or turned inside out. But in the latter case, the wind slides out over the edges again, so that there is no trouble in holding on to the umbrella.

The peculiar shape of the wing is only one of the ways by which the down-stroke is made to strike the air with more force than the up-stroke. If you will look at a quill-feather, you will see that, on each side of the central shaft or quill, there is a broad, thin portion, which is called the _vane_. The vane on one side of the shaft is quite broad and flexible, while that on the other side is narrow and stiff; and by looking at a wing with the feathers in their places, you will find that they are placed so that they overlap a little, like the slats on a window-blind. Each broad vane runs under the narrow vane of the feather beside it, so that, when the wing is moved downward, each feather is pressed up against the stiff narrow vane of the one beside it, and the whole wing forms a solid sheet like a blind with the slats closed. After the down-stroke is finished and the up-stroke begins, the pressure is taken off from the lower surface of the wing, and begins to act on the upper surface and to press the feathers downward instead of upward. The broad vanes now have nothing to support them, and they bend down and allow the air to pass through the wing, which is now like a blind with the slats open. By these two contrivances,--the shape of the wing, and the shape and arrangement of the feathers,--the wing resists the air on its down-stroke and raises the bird a little at each flap, but at each up-stroke allows the air to slide off at the sides, and to pass through between the feathers, so that nothing is lost.

So much for the way in which the bird is raised into the air. Rising in the air is not flying, for a balloon and a kite rise but do not fly. Now, how is a bird able to move forward? This is not quite as easy to understand as the other, but I hope to be able to make it clear to you. I must first say, however, that it is not done by rowing with the wings, for they move up and down, not backward and forward, and no amount of rowing up and down would drive a bird forward, any more than rowing backward and forward would lift a boat up into the air.

You will find, if you carefully examine a bird's wing, that all the bones and muscles are placed along the front edge, which is thus made very stiff and strong. The quill feathers are fastened in such a way that they point backward, so that the hind edge of the wing is not stiff like the front edge, but is flexible and bends at the least touch. As the air is not a solid, but a gas, it has a tendency to slide out from under the wing when this is driven downward, and of course it will do this at the point where it can escape most easily. Since the front edge of the wing is stiff and strong, it retains its hollow shape, and prevents the air from sliding out in this direction, but the pressure of the air is enough to bend up the thin, flexible ends of the feathers at the hinder border of the wing, so the air makes its escape there, and slides out backward and upward. The weight of the bird is all the time pulling it down toward the earth; so, at the same time that the air slides out upward and backward past the bent edge of the wing, the wing itself, and with it the bird, slides forward and downward off from the confined air. You will have a much better idea of this if you will cut out a little paper model of a bird's wing and watch the way in which it falls through the air.

Take a sheet of stiff paper and cut it in the shape shown in the diagram above, but considerably larger. Be very careful to have the two sides alike, so that they shall balance each other. Now fold up the front margin of each wing, along the dotted lines _a_, _a_, _a_, _a_, to form a stiff rim to represent the rim of bone along the front edge of a bird's wing, and cut out a small strip of wood, about as thick as a match and twice as long, and run this through the two slits, _b_, _b_, to represent the body of the bird. If you hold this model about three feet from the ground, and allow it to fall gently, you will see that, instead of falling straight to the ground, it will slide forward, and strike the ground two or three feet ahead of you. It is really its weight which causes it to do this, so that the statement that a bird flies by its own weight is strictly true.

This is true, also, of insects and bats. They all have wings with stiff front edges, and flexible hind edges which bend and allow the air to pass out, so that flying is nothing but sliding down a hill made of air. A bird rises, then, by flapping its wings, and it flies by falling back toward the earth and sliding forward at the same time. At the end of each stroke of its wings it has raised itself enough to make up for the distance it has fallen since the last stroke, and accordingly it stays at the same height and moves forward in a seemingly straight line. But if you watch the flight of those birds which flap their wings slowly, such as the woodpecker, you can see them rise and fall, and will have no trouble in seeing that their path is not really a straight line, but is made up of curves; although most birds flap their wings so rapidly that they have no time to fall through a space great enough to be seen. Birds also make use of the wind to aid them in flight, and by holding their wings inclined like a kite, so that the wind shall slide out under them, they can sail great distances without flapping their wings at all. They are supported, as a paper kite is, by the wind, which is continually pushing against their wings, and sliding out backward and downward, thus lifting or holding up the bird, and at the same time driving it forward.

The birds are not compelled to face the wind while they are sailing, but by changing the position of the wings a little they can go in whatever direction they wish, much as a boy changes his direction in skating by leaning a little to one side or the other. Some birds are very skillful at this kind of sailing, and can even remain stationary in the air for some minutes when there is a strong wind; and they do this without flapping their wings at all. It is a difficult thing to do, and no birds except the most skillful flyers can manage it. Some hawks can do it, and gulls and terns may often be seen practicing it when a gale of wind is blowing, and they seem to take great delight in their power of flight.

Of all birds the albatross is the most skillful in the art of sailing in the air. It is a large sea-bird, about the size of a swan, and has very long and powerful wings. It lives far out upon the open ocean, hundreds of miles from land, and spends nearly all of its life in the air, very seldom alighting upon the water. It flies almost entirely by the aid of the wind, and sometimes does not flap its wings for an hour at a time. Albatrosses often follow a ship clear across the ocean, or, rather, they keep company with the ship, for as they are able to fly one hundred miles an hour with ease, the rate at which a ship travels is much too slow for them; so they make long journeys ahead and behind, like a dog taking a walk with his master, returning occasionally to the ship to pick up any food which may have been thrown overboard.

NANCY CHIME.

BY S. SMITH.

Untarnished by the breath of fame,
Untouched by prose or rhyme,
The world has never heard that name,--
The name of Nancy Chime.

Domestic, friend, and monitor,
She served us long and well;
Not many "helps" could equal her,
And none, perhaps, excel.

No evil lurked within her breast;
Her face was always bright;
Her trusty hands, scarce needing rest,
Were busy day and night.

Her voice was sweet as voice of birds
That to each other call;
And when she spoke, her striking words
Were listened to by all.

E'en Baby Bunting--darling boy,
The happiest of his race--
Would clap his little hands with joy,
And look up in her face.

But none can reach perfection here;
Like all beneath the sun,
She, too, could err, and her career
Was not a faultless one.

She only did, here let me tell,
Each day the best she could;
Would young folks all but do as well,
The world might soon grow good.

But all is past! Ah! cold that face!
That bosom throbs no more!
Oh! must another take her place,
And we our loss deplore?

Nay, nay, we could not bear the pain
Of losing one so true;--
Old Nancy Chime shall tick again,
And be as good as new.

HOW HE CAUGHT HIM.

WHO PUT OUT THE TEA-PARTY?

BY ELLEN FRANCES TERRY.

One day, when I was a small girl, my little sister Katy and I found in the yard a dry-goods box, in which the new carpets had been sent home. As usual, we ran to where grandma sat knitting and nodding:

"Oh, grandma, _mayn't_ we have it?" cried I.

"Yet hab it, dranma?" echoed Katy.

"You know we never had a baby-house."

"No, nebber had no baby-'ouse."

"Oh, say yes!"

"'Ay 'et!"

"Do, do!"

"Pede do!"

Then, before she knew what she was to do, or say, or what she never had done, or said, we coaxed her to the back door and pointed to our treasure. She couldn't refuse us, and the box was given to us.

John made us a card-board chimney, and cut a square window in either end, for, of course, we set it on its feet, turning its back to the lane against whose fence it stood, looking into the yard. Grandma gave us red curtains for the windows, and a big striped apron, which hung across the front and did for a door. We had to have a door, for, when we took tea, the chickens came, without invitation, peeping inside, looking for crumbs. And, seeing what looked like a party, down flew, with a whir and rustle, a flock of doves, saying, "Coo-oo! how do-oo-do!" and prinking themselves in our very faces. Yes, we really had too many of these surprise-parties; for, another time, it was a wasp that came to tea, and flew from me to Katy, and from Katy to me, till we flew, too, to hide our heads in grandma's lap. Then she gave us the apron, which was very grand, though the blue stripes were walking into the red ones, and there were a good many little holes which let small arrows of light fly out. That was when we lighted the chandelier, and they (the holes and the arrows) were the very things to let people know what grand doings there were inside.

Then, when our crockery was arranged on the shelf at the back, a stool set in the middle for a table, our two small green chairs placed one at either end, and a good many nails driven into the "walls" to serve as hooks,--then we gave a party. The dolls were invited, of course, and their invitations Katy wrote on her slate. To be sure, the letters looked a good deal like Jack and Jill,--climbing up hill and tumbling down again,--still the dolls understood us. There were no little girls invited, because little girls couldn't have squeezed in, unless they were willing to be hung up, like the extra dollies.

But oh! wouldn't they have liked to go? We had ice-cream, just made of vanilla, cream-candy, and water,--delicious! Then there was a whole tea-potful of chocolate-tea, which was a chocolate-cream drop scraped fine and mixed with water. Do just try it sometime. Thimble-biscuits, too, and holes with cookies round them. I never expect to be as happy again as I was when I dropped the curtain at half-past four precisely, and lighted the chandelier, which I forgot to say was a candle cut in two, stuck in cologne-bottles of different shapes and colors.

We well knew--for didn't we go out twice to look?--how splendidly the light streamed through the two windows and the eight holes. Why, the chickens knew it, too, on their perches, for they opened one sleepy eye after another, solemnly changed legs, and dozed off again. Those long rays of light, playing truant, ran down the lane and flashed into the very eyes of naughty Billy Quinn, who was going home from a visit, whistling, and with his hands in his pockets.

Of course the dolls arrived promptly, and took off their shawls in the best bedroom, which was that convenient shelf that was turned into anything on short notice. The baby-dolls had to go early to bed under the table, and you can imagine how much pleasanter it is to say, "Bed-time, children!" than to have it said to you. Mrs. Green was a perfect little Mrs. Herod in her treatment of her children. Indeed, their yells under punishment were heart-rending; but when she was only dear Katy she was tender as one of those cooing doves.

So we ate up the ice-cream, and turned the tea-pot upside down to squeeze out the last drop of chocolate-tea. Mrs. Green was just doing this very thing when the most dreadful event happened. Crash!--bang!--clatter!--the whole world had turned upside down. Out went the lights, and everything fell together in a dismal heap; but whether up or down nobody could tell. There was a splash of cold, cold water in my face as the wash-bowl and pitcher fell and crashed beside me. Katy lay with her small nose buried in the butter-plate. _The house had tumbled over!!_

For a few seconds not a sound was heard, but then there was a half-stifled burst of laughter, which quickly died away as some thickly shod feet scampered down the alley. Yes, the beautiful house was tipped over, and the tea-party put out, as an extinguisher is slipped over a candle, or a hat clapped upon a butterfly. Inside, there was a confused heap, with legs uppermost,--table-legs, chair-legs, little legs clad in white stockings, and, mixed hopelessly up with these, the dolls, the dishes, the candles.

This heap, however, was silent only for a moment. Then a feeble cry struggled up through it,--a cry which, reaching the upper air, grew loud, doubled itself, became two cries, and rushed out through a window, which, having lost its way, was where the roof ought to be. Then growing fast and shrill, the cry ran toward the house, waking up the Brown baby, who at once joined in. The rooster waked suddenly, and feeling that something had happened, thought it could do no harm to crow, and that agitated his household to the last hen. Then to the cackling and crowing, Beppo added a bark of duty, and nearly turned inside out, tugging at his chain, and howling between times. The canary began his scales, and the scream grew and grew and rushed into the house through every door and window. Uncle John was reading the paper, but, hearing the fearful uproar, he dashed into the yard, turned back the house with one hand, with the other picked out from the heap of legs all the white ones, and dragged us from the wreck of our residence. It was quickly done, but not too soon, for a little flame, which was hiding under the close mass of ruins, now hopped merrily up on the tarletan skirts of Alice Isabella, the prettiest of the dolls.

While we were being taken to grandma to be cried over and comforted, and the poor old house lay on its side forgotten, that flame finished off poor dolly, ran up to the roof, ate up the red-striped curtain in the twinkling of an eye, and, in fact, made short work of the whole thing. We knew nothing of this that night, but were so honored and indulged as to make us think everything else had turned a new leaf as well as the house.

The next morning, grandma, coming into the breakfast-room, was called to the window by Uncle John, who was looking at something in the yard. There was a forlorn little figure sitting on a log among the charred embers of the burnt house. It was I, sobbing as if my heart would break, and beside me was Katy, who stood sadly by, trying with a corner of her apron to dry my tears. But her eyes were wet, too, and in the fat arms were squeezed a leg and shoe, which was all that was left of Alice Isabella.

What wicked eye had watched the festivities through the window, or what cruel heart had yielded to the temptation to turn over the house upon it all, we never knew. I heard that Billy Quinn was punished that night for coming home late to supper, and now, looking impartially at the matter over all these years, I am inclined to think it was that very Billy Quinn, and no other, who put out the tea-party.

THE FOX, THE MONKEY, AND THE PIG.

BY HOWARD PYLE.

The fox, the monkey, and the pig were once inseparable companions. As they were nearly always together, the fox's thefts so far reflected upon his innocent associates, that they were all three held to be wicked animals.

At length, the enemies of these three laid a snare, in a path they were known to use.

The first that came to the trap was the pig. He viewed it with contempt, and, to show his disdain of his enemies and his disregard for their snare, he tried to walk through it with a lofty tread. He found he had undervalued it, however, when, in spite of his struggles, he was caught and strangled.

The next that came was the monkey. He inspected the trap carefully; then, priding himself upon the skill and dexterity of his fingers, he tried to pick it to pieces. In a moment of carelessness, however, he became entangled, and soon met the fate of the unfortunate pig.

The last that came was the fox. He looked at the snare anxiously, from a distance, and, approaching cautiously, soon made himself thoroughly acquainted with its size and power. Then he cried, "Thus do I defeat the machinations of my enemies!"--and, avoiding the trap altogether, by leaping completely over it, he went on his way rejoicing.

DAB KINZER: A STORY OF A GROWING BOY.

BY WILLIAM O. STODDARD.