CHAPTER I - GETTING READY

As soon as you have finished breakfast, and brushed your teeth and gone to the toilet, you are ready to run out of doors to play, if you have plenty of time, or, if not, to start for school.

Doesn’t it seem a nuisance, in winter time, to have to put on a coat and overshoes and a cap or a hood, and sometimes leggings and mittens, too? But your mothers know what is best for you; and when you are young and growing fast, you have so much more surface in proportion to your weight than when you are grown up, that you lose heat from the blood in your skin very fast; and unless you are warmly dressed, you become chilled.

When you are chilled, you are using up, in merely trying to keep yourself warm, some of the energy that ought to be used for growing and for working. It has been found out by careful tests that children who are not warmly dressed, and particularly whose arms and legs are not warmly covered, do not grow so fast as they ought to, and more easily catch colds and other infections. So take time to put on your cap and your coat, if the weather is cold; and, if it is snowy, to button on leggings over your stockings; and then you can play as hard as you like, and run through the snow, and keep warm and rosy and comfortable.

Wool is one of the best stuffs for coats and dresses and stockings and gloves and caps, not only because it is warm, but also because it is lighter in weight than anything else you could wear that would be equally warm, and because it is porous; that is, it will let the air pass through it, and the perspiration from the body escape through it.

Don’t wear any clothes so tight that you cannot run and jump and play and fling your arms and legs about freely, or so fine and stylish that you are afraid of getting them soiled by romping and tumbling.

It is best to wear fairly heavy, comfortable shoes with good thick soles; then you will not have to wear rubbers, except when it is actually pouring rain, or when there is melting snow or slush upon the ground. Felt, or buckskin, or heavy cloth makes very good “uppers” for children’s shoes; but only leather makes good soles.

It is best not to wear rubbers too much, because the same waterproofness, which keeps the rain and the snow out, keeps the perspiration of your feet in, and is likely to make them damp. When they are damp, they are as easily chilled as if they had been wet through with rain or puddle water. Always take off your rubbers in the house or in school, because they are holding in not only the water of perspiration, but the poisons as well; and these will poison your entire blood, so that you soon have a headache and feel generally uncomfortable.

CHAPTER II -  AN EARLY ROMP

The minute you are outside the door, the fresh morning air strikes your face, and you draw four or five big breaths, as if you would like to fill yourself as full as you could hold. If you have had a good night’s sleep and a good breakfast, the very feel of the outdoor air will make you want to run and jump and shout and throw your arms about. This warms you up finely and gives you a good color; but if you keep it up long, you will notice that two things are happening: one, that you are breathing faster than you were before; the other, that your heart is beating harder and faster, so that you can almost feel it throbbing without putting your hand on your chest.

If you run too hard, or too far, you begin to be out of breath, and your heart thumps so hard that it almost hurts. What is your heart doing? It is pumping; it is trying to pump the blood fast out to your muscles to give them the strength to run with.

Of course you have seen a pump? Perhaps some of you have to pump water every day at home. You take the handle in your hands, lift it up, then press it down, and out pours the water through the spout; and, as you keep pumping, the water spurts out every time you press the handle down. It is hard work, and your arms are soon tired; but, as you cannot drink the water while it is down in the well, you must pump to bring it up where you can reach it.

Just so the heart pumps to keep the blood flowing round and round, through the muscles and all over the body. If you put your finger on your wrist, or on the side of your neck, you can feel a little throb, or pulse, for every spurt from your heart-pump; and that means for every heart-beat.

This heart-pump is made of muscle, and is about the size of your clenched fist. And just as you can squeeze water from a sponge or out of a bulb-syringe, by opening and shutting your hand around it, so the big heart muscle squeezes the blood out of the heart. It squeezes it out from one side of the heart; and then, when it lets go, the blood comes rushing in from the other side to fill the heart again. So the heart goes on squeezing out and sucking in the blood, all day and all night as long as we live.

When the blood comes to the muscles, it is a beautiful bright red; but after the muscles have taken what they want of it for food to burn, and warm you up, the “ashes” and the “smoke” go back into the blood and dirty its color from red to purple. Then the blood is carried to the lungs, where the fresh air you breathe in blows away the “smoke” and makes the blood red again.

The blood is pumped all over the body through tubes or pipes, called blood vessels. Those that carry the red blood out from the heart, we call arteries. They are deep down under the skin, and we cannot see them. The pipes that carry the purple blood from the muscles and other parts back to the heart again, we call veins; and some of these are so close to the surface that we can easily see them through the skin. Let your hand hang down a minute or two, then you can see the veins on the inside of your wrist, or on the back of your hand, if it is not too fat.

The muscles, the brain, the skin, and other parts of the body get liquid food from the blood by “sucking” it through the walls of the smallest of the blood vessels, for these walls are very thin. In the same way, when waste passes from the muscles or the skin into the blood, it, too, soaks through the thin walls of the tiniest blood tubes, called capillaries.

Your heart beats or throbs about seventy-five times in a minute when you are well. Look at the second hand of a watch, while you count the beats in your wrist or in your neck.

Does your heart ever become tired? Not while you keep well, unless you over-drive it by running or wrestling too hard. It can rest between the beats. But the heart muscle, like any other muscle, must have plenty of good red blood to feed on. You put food into the blood by eating good breakfasts and dinners. The more you run and jump and play, the more work the heart has to do and the stronger it grows; and a good morning romp before school will send the blood flowing so merrily round from top to toe that you will feel fresher and brighter all the day.

CHAPTER III - FRESH AIR-WHY WE NEED IT

The heart is not the only thing that goes faster and harder when you run about in the morning and play hard. You are breathing faster and deeper as well, as if there were something in the air outside that you needed in your body as much as food.

But, of course, you know that air is not good to eat. It has no strength in it, as food has; it isn’t even a liquid like milk or coffee or tea. It is so thin and light that we call it a gas. Indeed, I suppose it is pretty hard for you to believe that air is a real thing at all. But all outdoors is full of the gas called air, and everything that seems to be empty, like a room or an empty box, is full of it.

You cannot even smell it, as you can that other gas which comes through pipes into our houses and burns at the gas jets; nor can you see it like the gas that comes out of a boiling kettle or from the whistle of a locomotive, and which we call steam. This is simply because air is so pure that it has no smell, and is so perfectly clear that we can see right through it. Almost the only way that we can recognize it is by feeling it when it is moving. But it is a very real thing for all that; and, like sunshine and food, is one of the most important things in the world for us.

What is it that air does in the body? We must need it very much, for we die quickly when we cannot get it: it takes us only about three minutes to suffocate, or choke to death, if we can’t get it.

You remember that the blood is pumped out from the heart, all through the body. Everywhere it goes,-to the feet and the hands and the head,-it is carrying two things: food that it has sucked up from the food tube, and hundreds and hundreds of tiny red sponges called red corpuscles. These little sponges are full of air which they sucked up as the blood passed through the lungs. When we stop breathing,-that is, taking in air,-the little red sponges of course can’t get any air to carry to the different parts of the body.

The body is made up of millions of tiny, tiny animals, called cells,-so tiny that they can be seen only under a microscope. Each of these cells must have food and air, just like any other animal. They eat the food the blood brings to them, and they take the air from the red corpuscles in the blood. With the air as a “draft,” they burn up the waste scraps, as we burn scraps from the kitchen, in the back of the stove.

Suppose you light a candle and place it under a glass jar and watch what will happen. The flame will become weaker and weaker, and at last it will quite go out. You might think at first that the wind blew it out; but how could the wind get through or under the jar? No, the glass keeps all the outside air away from the flame; and that is just the reason why it does go out. Unless it has fresh air, it cannot burn. There is something-a gas-in the air that makes the flame burn, and when it has used up all this gas inside the glass, and can’t get any more, it stops burning.

Now you will want to know what this gas in the air is. When we write about it, we use its nickname, the large capital letter O; but its whole name is Oxygen.

Just as the candle flame must have oxygen to keep it burning, so our cells must have oxygen to burn their impurities, or waste; and if they don’t get the oxygen, and can’t burn their impurities, they are poisoned by them and “go out,” or die.

You can see the flame when the candle is burning, but you can’t see the fires that burn in our bodies; there are no real flames at all. I know it is hard for you to believe that there can be any burning when our bodies are so wet and damp. But if you can’t see it, you can easily feel it. Blow on your hand. How warm your breath is! Touch your hand to your cheek. It is quite warm, too. If you run or play hard, you sometimes become so hot that you want to take off your coat. That is because your fires are burning faster. The muscles are using more food and making more scraps to be burned. You breathe faster and faster till at last you are “out of breath” and feel as if you would smother or choke. The blood has hard work to bring oxygen enough to keep the fires going.

After the cells have burned the food scraps, they turn the “ashes” and “smoke” back into the blood-stream that is always flowing past them. If the cells did not do this, they would soon smother to death, just as you could not possibly live in a house without chimneys to carry off the smoke. And, of course, the blood wants to get rid of this waste just as quickly as possible.

Part of the waste in the body is liquid, like water, and can flow away through the blood pipes without needing to be burned. Some of this watery waste comes out through the skin and stands in beads or drops upon it. That is the part we call perspiration, or sweat. The rest of it goes in the blood to another strainer called the kidneys, passes through this as urine, and is carried away from the body as the waste water from the bathtub and the sink is carried away from a house.

For the “smoke” Mother Nature has still another beautiful plan. She sends the blood-stream flowing through the lungs, where it can send off its “smoke” and then get fresh air to carry to the cells in the muscles. When you breathe out, you are sending out the “smoke”; and when you breathe in, you are taking in fresh air.

Our body “smoke” is not brown or blue, like the smoke from a fire; it is a clear, odorless gas, called carbon dioxid. This is the same gas that makes the choke-damp of coal mines, which suffocates the miners if the mine is not well ventilated; and the same gas that sometimes gathers at the bottom of a well, making it dangerous for anyone to go down into the well to clean it. And this gas is poisonous in our bodies just as it is in the mine or the well.

You see, then, how important it is that we should live much of our lives in the clear pure air out of doors, and should bring the fresh air into our houses and schools and shops. “Fill up” with it all you can on your way to school, for the best of air indoors is never half so good as the free-blowing breezes outside.

CHAPTER IV - FRESH AIR - HOW WE BREATHE IT

When you are running and breathing hard, and even when you are sitting still and breathing quietly, air is going into your lungs and then coming out, going in and coming out, many times every minute. How does the air get in and out of the lungs? It will not run in of itself; for it is light and floats about, you know. Here, again, Mother Nature has planned it all out. She has made us an air bellows, or air pump, to suck it into the lungs. First we’ll see what shape this pump is, and then how it works.

Stiff rings of bone called ribs run round your body, just like the hoops in an old hoop skirt, or like the metal rings round a barrel. Here is a picture of the bones of the chest. Perhaps your teacher can show you the skeleton of some animal. You will notice how the rings, or ribs, slant and are joined by hinges behind to the backbone and in front to the breastbone. It looks somewhat like a cage, doesn’t it? Put your hands on the sides of your chest and you can feel your own ribs. Do they slant upward or downward?

This chest-cage is our breathing-machine. Before I tell you how it pumps, I want you to get a pair of bellows and see how they work. When you lift up the handle of the bellows, you make the bag of the bellows larger so that it sucks in air; and when you press the handle down again, the air puffs out through the nozzle.

Our air machine, though it is somewhat different from the bellows in shape, works in exactly the same way. You remember that you found that the ribs slant down and can be moved on hinges. Suppose, now, you place your hands against your ribs and feel the ribs lift as you draw in a long breath. The air will be sucked into your nose just as it was into the bellows when you raised the handle. By lifting your ribs, you have made the chest-cage larger; and the air has rushed into your nose, down your windpipe, and filled your lungs. If you breathe very deeply, you will find that your stomach, too, swells out. This shows that the muscular bottom of the cage, called the diaphragm, has been pulled down, making the cage larger still.

In this chest-cage are millions of tiny air bags that make up the lungs; and every time you take a breath, the air bags are puffed out with the fresh air that comes rushing in. By the time you let your ribs sink again, the air has given its oxygen to the blood, and the blood has poured its carbon-dioxid smoke into the air bags for you to breathe out. Nature, with the same bellows, pumps in the oxygen and pumps out the “smoke.”

Now, we breathe into our lung-bellows whatever air happens to be around us. So we should take care that the air around us is fresh air.

Unless the air were kept in motion by the heat of the sun, causing breezes and winds, it would become stale and wouldn’t do at all for our lung-bellows to use. The air we breathe must be kept moving and fresh if it is to make us feel bright and strong and happy. Mother Nature has given us miles upon miles and oceans upon oceans of this clear, fresh air to breathe-“all outdoors,” in fact, as far as we can see around us and for miles above our heads. She sends the winds to move the air about and blow away the dust and dirt; and the sunshine, you remember, not only to warm the air and keep it moving, but to burn right through it and kill the poisons. But this brings us to something else.

You have learned that the air we breathe out would soon smother us, just as smoke would; and now we will see why. If you blow against the window pane on a cold day, the glass is no longer clear; and when you look at it closely, you see that it is covered with tiny drops of water. This is part of the breath you have just blown out. If the room is cold enough, you can see your breath in the air; that is, the steam in your breath becomes cold and appears as tiny water-drops. You have seen how in the same way, the steam, an inch or so from the spout of the teakettle, cools, making little water-drops that float in the air like clouds. Part of the breath, then, is water; but most of it is a gas, and you can’t see it at all as it floats away into the air about you.

If your teacher has a glass of limewater, and will let you breathe into it through a tube, you will see that your breath soon makes the water look milky. This shows that the gas in your breath is not like the air about you; because air was all over the top of the limewater, yet did not change it at all. The milky look is caused by carbon dioxid, one of the poisons in your breath.

When some people come close to you, you want to turn away your head, because you do not like the smell of their breath. Even when one is quite well, the breath has a queer “mousey” odor, so that we never like to breathe the breath of another person. This disagreeable odor comes not only from the lungs but from the teeth.

We are always breathing out poisons into the air. One of these you can see in the milky limewater, and others you can smell when you happen to come close to anyone else.

If you blow on your fingers, you feel that your breath is much warmer than the air. If people are crowded together in rooms with doors and windows shut, their breath soon heats and poisons the air, until they begin to have headache, and to feel dull and drowsy and uncomfortable. If they should be shut in too long, without any opening to let in the fresh air, as in a prison cell, or in the hold of a ship during a storm, the air would become so poisonous as to make them ill, and would even suffocate them and kill them outright. Even the bees found this out thousands of years ago; and in their hives in hot weather they station lines of worker-bees, one just behind another from the door right down each of the main passages, whose business it is to do nothing but keep their wings whirring rapidly, so that they fan a steady current of fresh air into every part of the hive.

How does Mother Nature get rid of these poisons from our breath? Of course, you say, “She uses the wind and the sunshine.” Yes, the winds can whisk up the poison and blow it away so fast, and the sunshine can burn up the horrid smell so quickly, that even the air above big cities, and in their streets, is quite clean enough for us to breathe, except where the people are very closely crowded together and very dirty. Mother Nature wants all of us to help in keeping the air clean. This we can do by keeping ourselves and our houses clean, and by being careful not to leave scraps of waste, or dirty things, in the streets and cars and parks and other public places. And you children ought to be very careful about your school yard and the halls and the classrooms, where you spend so much of your time.