Ear-trumpet.
Sound, I have told you, spreads in all directions in vibrations or waves. Now the more of these waves the ear can catch, the more distinct is the hearing. Some animals that need to hear very well have very large ears. Here is one, the long-eared bat. He must hear very well indeed, for his monstrous ears must catch a great many of the waves of sound. We could hear better if our ears were larger; but large ears would not look well on our heads; and we hear well enough commonly. Sometimes, when we do not hear as distinctly as we wish to, we put up the hand to the ear, as you see represented on the opposite page. This helps the hearing by stopping the waves of sound, and turning them into the ear. Those who are very deaf sometimes have an ear-trumpet, as it is called. In using it, the large trumpet end is turned toward the person speaking, so as to catch the vibrations, while the tube part of it is in the ear.
Ears of rabbits, deers, etc.
Some animals can turn their ears so as to hear well from different directions. How quickly the horse pricks up his ears when he sees or hears something that he wants to know more about; and then he can turn his ears backward when he wants to do so. It is in such timorous animals as the hare, the rabbit, and the deer, that we see the ears most movable. They are on the watch all the time for danger, and the least sound that they hear they turn their ears in the direction of it. Their ears, too, are large, so that they hear very easily.
How the ear is guarded.
I have told you how the eye is guarded. The ear is well guarded also. I do not mean its outer part: it is the inner parts, where the hearing is really done, that are so well guarded. You remember that I told you that there are passages filled with a fluid. The nerve of hearing has its fine, delicate fibres in these passages. They feel the shaking of the fluid, and tell the mind of it. Now it is necessary that this part of the hearing apparatus should be well guarded; for this reason, these passages are inclosed in the very hardest bone in the body.
How the ear-wax guards the ear.
Then, too, the very entrance into the ear is well guarded, and in a curious way. The pipe that leads into the drum of the ear is always open, and you know bugs are very apt to crawl into such holes. What do you suppose is the reason that they do not often crawl into the ear? There is something there to prevent them. It is the wax. They probably do not like the smell of it, and so, if they come to the entrance, they turn about. Once in a while one goes in, and then he is prevented from doing much harm by the wax. He is soon covered with this, and it is so sticky that it keeps him from kicking very hard. And, after all, though he may cause some pain, he can not get at the delicate part of the machinery of the ear. He dies after a while, if he is not got out, and perhaps the bitterness of the wax has something to do with killing him.