thing like leather. Do you see why brown and black people are natives of hot countries where there is much sunshine, while the fairest nations of the white race live in cold, northern countries where there is the least sunlight?
WHY AND HOW WE GO TO SLEEP
"Why do we go to sleep?" That is what the little "why" boy asked his mama.
"Because we are sleepy."
"Why do we get sleepy?"
"Because we are tired."
"But why do we get tired?"
"Oh, dear!" The little boy’s mama said she never knew such a tiresome child for asking questions. He made her so tired she was sleepy. Now what had happened to her?
We all have two kinds of nerves. One kind makes us feel, see, hear, touch and taste. Their tiny, sensitive ends come to the surface all over us, and telegraph sensations to the brain. The brain telegraphs to the nerves of motion to make the body do things. When they are used all day long, these sensation and motor nerves get tired of sending messages. The brain gets tired of receiving them and sending orders. The muscles and bones of the body get tired of carrying out these orders.
You see, everything is made tired, or worn out by use—just as your shoes are. You have to throw a pair of tired-out shoes away. You cannot do that with your body. But it will make itself as good as new, if you give it a rest every so often. In sleep the wearing out is stopped. The nerves and brain—which is a big bundle of nerves, a switch-board for "central"—the muscles and bones all stop working. The heart, lungs, stomach, and all food-making organs, go right on working, although not as rapidly as when we are awake. The fires of life burn low. So the day's waste is made up, and we awake rested.
While grown people rest when asleep, children both rest and do most of their growing. Children need more sleep than grown people. Children who have too little sleep are apt to be small and weak, and not as bright in their minds as they might be. But how do we go to sleep?
By shutting all the little doors to the brain. Nature begins it. At the end of a day, we do not feel, hear or see as keenly as when we
