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, but down 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.
