CHAPTER XXVI.
WINGS.
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.