Bones of a bird’s wing like the bones of the arm and hand.
Birds walk upon two legs as we do; but, instead of such hands as we have, they have hands made for the purpose of lifting them up in the air. The bones in a bird’s wing are very much like the bones in our arms and hands; but they make a frame-work for the feathers of the wing to spread out from. The bones that go out almost to the very end of the wing are like the bones of our fingers, only they are much longer.
A bird’s wing, when it is stretched out, is a very large thing. It needs to be large to do its work well. A bird could not fly with small wings. You know that by trying very hard you jump up into the air a very little way. But see, the bird goes up very easily as high as it pleases, and does not seem to be tired. This is because its wings spread out so broadly.
Why wings are so large.
The reason that birds need such large wings is this. As the bird rises by pressing upon the air, it must press on a good deal of air to do this. If it pressed upon only a little air it could not rise at all, because the air gets out of the way so easily when it is pressed upon. Swimming is flying in the water; and, as water when pressed does not get out of the way as easily as air does, the tail and fins, with which fishes swim, do not need to be as large as the wings of birds. For the same reason, hands and feet answer very well for us to swim with, though we can not fly with them. I shall tell you more particularly about this in Part Third.
Wings of the condor.
Here is a very large bird, the condor. To lift such a heavy body as he has up into the air must require very large wings, and you see that he has them.
Muscles that work the wings of birds.
Now, to work such broad wings, the bird has very stout muscles. You know how the breast of a bird stands out. You see it here in the condor. This is because the muscles with which it works its wings are there. You can see that this is the reason when a bird is cooked. The meat, you know, is very thick on the breast-bone—thicker than in any other part of the body. If we had as large muscles on our breast-bones we should look very strange. But we do not need such large muscles to work our arms as birds do to work their wings.
Why men can not fly.
A man could not fly if he had wings fixed on to his arms. It has been tried. I knew a man once to make something like wings for himself. After he had made them, he went up on to the roof of a shed to try them. He jumped off and flapped his wings, butdown he came about as soon as if he had no wings, and he was so much bruised that he was not disposed to try the experiment again. Now why could he not fly? It was not for want of wings. There the wings were, and he had made them right, for he had shaped them like the wings of birds. They were large enough and light enough; the difficulty was, that the muscles of his arms were not strong enough to work them well. They were arm-muscles and not wing-muscles. A man can not be like a bird merely by having wings. He must have a bird’s flying muscles, or he can not fly.
Short wings.
The ostrich.
Different birds have wings of different sizes. Those that fly very far and swiftly have the largest wings. The wings of the hen are not large enough to carry her far up into the air. The most that she can do is to fly over a very high fence; and if her wings are partly cut off, or cropped, as it is called, she can not even do that. There are some birds that do not use their wings in flying.The ostrich, represented on the previous page, is a great runner. He can not fly, but his wings help him some in running.
In what way the wings act in raising birds and carrying them along I will explain to you in Part Third, when I come to tell you about the air.
The beautiful motions of birds.
The swallow.
How beautiful are the motions of many of the birds as they fly in the air! How easily and gracefully their wings work! See that bird as it goes up and up; and now see it as it makes a turn, and comes down so swiftly on its outstretched wings, taking a beautiful sweep off at a distance; and then up it goes again to come down, in the same way that boys do when they travel up a long hill to slide down so swiftly on their sleds. The swallow, as he has this fine sport, is, at the same time, getting his living. As he skims along close to the ground or the water, as represented here, quick as thought he catches any unlucky fly that happens to be in his way.
The humming-bird.
Especially beautiful are the motions of the humming-bird. See him as he stops before some flower fluttering on his wings, or as he darts with them from one flower to another. The muscles of his wings are very nimble workmen. Our muscles can make no motions as quick as these.
The structure of feathers.
Did you ever examine a feather from a bird’s wing to see whata curiously-made thing it is? The quill part of it is very strong, but, at the same time, light. The plume or feather part is quite strong also. It is made up of a great many very thin and delicate flat leaves, as we may call them, which are locked together curiously by fine teeth on their edges. If you separate them they soon come together again, and are locked as fast as ever. You can see the teeth by which they hold on to each other very well with a common microscope.
The delicacy of a bat’s wing.
No wonder that the bat can fly so swiftly with such very broad and light wings as he has. Did you ever observe how a bat’s wing is made? It is a very curious and really beautiful thing. It is an exceedingly fine, thin skin, on a frame-work of long, slender bones. These are to it what sticks of whalebone are to an umbrella; and the wings can be folded up somewhat as an umbrella is. This is done whenever the bat is not flying. When it is on the ground it is very awkward in its movements. It can not get a start to fly, and so it pushes itself along with its hind feet, at the same time pulling by the hooks in its wings, which it puts forward, first one and then the other, hooking them into the ground. It never likes to get upon theground, and it takes its rest always, as you see represented on the previous page, by hanging itself up by the two hooks in its wings.
The vampire bat.
Here is a picture of the vampire bat, a native of South America, that lives by sucking the blood of animals when they are asleep.
Locust’s wing.
Nothing is more delicate than the wings of insects. They are like gauze; but they have a frame-work that makes them quite firm, just as leaves are firm from the ribs that are in them. Here is a drawing of the wing of a locust. But you can get no idea of the beauty of insects’ wings from such drawings. You must examine the wings themselves. Even the wing of a common fly is very beautiful, so delicate is its structure.
Wing of the katydid.
The wing of the katydid, as it is called, is peculiarly beautiful. Here it is. You see that it is very delicate. Its color is a light green. You see that rather thick three-cornered ridge at that part of thewing which joins the body. There is a similar ridge on the wing of the other side. In the space within this ridge there is a thin but strong membrane or skin, so that it makes a kind of drum-head. It is the rubbing together of these two drum-heads on the wings that makes the noise. It is a queer sound. There is no music in it, but the katydids seem to enjoy making it.
How the katydid makes its noise.
How you can stop it.
The katydid commonly makes three rubs at a time with its drum-heads. It sounds somewhat as if it said Katy-did, and from this comes its name. Sometimes there are only two rubs, and then you can fancy that it says She did or She didn’t. The katydids, you know, are all quiet in the daytime, but when evening comes they are very noisy. I have often been amused to hear them as they begin just at dusk. One will begin, and perhaps say its Katy-did several times; then another, on a neighboring tree, will reply; and after a little time the whole tribe will be at work. Each one appears to rest upon it after each rubbing, and so it seems as if they answered each other from one tree and another. It is curious that you can at once stop the noise of this insect by striking the trunk of the tree on which he is with your hand.
Questions.—What are the bones in a bird’s wing like? What is said about the size of birds’ wings? What about the muscles that work them? Why can not a man fly if he makes wings for himself? What birds have the largest wings? What is said about the hen? What about the ostrich? What is said about the motions of birds in flying? What is said of the swallow? What of the humming-bird? Tell about the parts of a feather from a bird’s wing. What is said about the bat’s wings? What about its motions on the ground? How does it rest? What is said about the wings of insects? How does the katydid make its noise?
Questions.—What are the bones in a bird’s wing like? What is said about the size of birds’ wings? What about the muscles that work them? Why can not a man fly if he makes wings for himself? What birds have the largest wings? What is said about the hen? What about the ostrich? What is said about the motions of birds in flying? What is said of the swallow? What of the humming-bird? Tell about the parts of a feather from a bird’s wing. What is said about the bat’s wings? What about its motions on the ground? How does it rest? What is said about the wings of insects? How does the katydid make its noise?