 
We say that a room with no furniture in it is empty. But this is not exactly true. There is one thing that the room is full of to its very top. It is something that you can not see. But it is as real a thing as the furniture. This thing is air. If you take all of your books out of the box in which you keep them, you say there is nothing left in it. But the box is full of air. When you shut it up and put it away, you put away a box full of air. When the books were in it, it was full of books and air together. Now it is full of air alone. The air is everywhere. It is always ready to go where there is a place for it. Every crack and crevice is filled with it. You see a little boy playing with a ball. What is it that he is throwing against the wall? It is a rubber ball, you say. But is Suppose that you prick a hole in the ball and squeeze it. It is now good for nothing. But the rubber is all there. Why is the ball good for nothing? It is because the air which filled the ball and made it round has escaped. The ball is of no use unless you can keep it full of air. Perhaps you think that air does not weigh anything. But it does weigh something, though very little, and its weight is well known. You can not see air, but you can sometimes feel it. You can not feel it while it is still if you are still at the same time. You can feel it only when it is in motion. When the wind blows upon you, it is air in motion that you feel. When you fan yourself, the air strikes upon your face, and you feel it. When there is a gust of wind, the air comes against you just as a wave of water does. Sometimes we say the wind blows very When the air moves very fast, it sometimes does a great deal of harm. It roots up trees and blows down houses. The air is clear, like glass. That is, it lets you see through it. But when you look up through the air, you see that it is of a blue color. You call the blue air the sky. The sky is the blue air that surrounds the earth. —Worthington Hooker. |
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