Someday there no longer will be any coal or oil for man to use. How soon can not be predicted exactly; there are differences of opinion among scientists. Yet that time will surely come—one thousand, ten thousand, or perhaps one hundred thousand years from now—if we continue using fuel at the present rate. How, then, will man do the world’s work? Trains and steamships would stop, since they require coal or oil. A great many of the machines operated by electricity would cease to turn because most electric generators are driven by engines requiring steam or oil. The few that are driven by water turbines would be hardly sufficient for modern purposes. Electric cells and batteries can not do the work. The automobile would be motionless. No airplane could leave the ground.

Many homes would be cold, and most factories would be silent. Of course, we should still have the wind and flowing water, such wood as could be had from forests and the fuel that can be manufactured from plants. Yet modern civilization could not get along on these sources of power alone.

Few of us realize how much we depend upon coal and oil. What are these substances and how did they accumulate on and in the earth? For the present it is sufficient to say that coal and oil are the remains of certain plants and tiny animals which lived millions of years ago. These ancient living things used sunshine, just as plants and animals do today. Each time we burn a lump of coal, and each time we “step on the gas,” we are using up the energy of ancient sunshine.

The sun is still shining and its energy is being used by living things that could some day form great deposits of coal and oil. But we can not afford to wait for that slow process. A way must somehow be found for putting to use more of the present-day sunshine; or else we must find sources of energy that do not depend upon the sun. Scientists are beginning to make progress in both directions. Let us consider first what might be done to harness the sun for doing some of the work of the world.

Day after day, the sun pours out vast amounts of energy. It is estimated that the earth’s surface receives from the sun each year the equivalent of many thousand horsepower for every square mile. If we could make good use of the energy absorbed by even a dozen square miles the threat of a coal-and-oil famine would be banished forever. In the last one hundred years, the minds of many men have been busy trying to solve this problem.

In the year 1866, Emperor Napoleon III of France visited the shop of a French inventor named August Mouchot. In the yard of the shop stood a large, cone-shaped object resembling a huge lampshade. The opening of the cone was directed toward the sun; its inside was lined with a thin film of silver. At the small end of the cone lay a small copper box, blackened on the inside. The Emperor was told that this curious device was a solar engine, that is, a sun engine. The rays of the sun were gathered by the cone and reflected by the silver lining down upon the small copper box which contained water. The heat caused the water to boil. So impressed was the Emperor that he urged his government to support and finance the building of many of these solar engines. Yet, the scheme was not very successful.

After Mouchot came several other inventors of sun engines. All of them used one or more of three important arrangements for collecting the sun’s rays—the conical mirror; the cylindrical reflector, and the hot-box - an airtight box, black inside, and covered with two layers of glass. Heat waves pass through glass; and black absorbs heat.

A solar engine was set up in the Arizona desert in 1904. It used a cone-shaped reflector and weighed about 8,300 pounds. Seven hundred square feet of sunshine was collected, which boiled water into steam, which, in turn, operated an engine. In 1913 a solar engine erected in Egypt gathered sunshine falling on an area of 13,000 square feet. This engine developed about 55 horsepower every hour. However, the machine proved to be too costly and could not be kept running easily.

One of the most workable solar engines ever built stands atop Mount Wilson in California. It consists of a large cylindrical aluminum mirror that is free to rotate about an axis parallel to that of the earth’s. A clock mechanism causes the mirror to follow the apparent motion of the sun. The rays of the sun are focused on three continuously connected oil-filled glass tubes about six feet long. Each of these tubes is covered with two other tubes which enclose a vacuum, so that very little heat is lost by the oil. As the oil gets warm it rises and soon a circulation is set up from the oil tubes to a storage tank and from the tank to the tubes. As this continues in the sunshine, the oil gets warmer and warmer, sometimes reaching a temperature of about 390 degrees Fahrenheit—which is hot enough to bake bread, cook food or boil water into steam for power purposes.

Seven hours of sunshine a day are enough to keep the machine going day and night at a temperature near that of boiling water. This machine is sometimes called a sun cooker.

There have been other efforts to make use of direct sunshine. One of the most interesting is to use the sun’s heat to produce cold. You are familiar with the type of kitchen refrigerator which is operated by a gas flame. The heat of this flame evaporates a specIal liquid called a refrigerant. The evaporated refrigerant (now a gas) is then compressed. When the gas is allowed to expand again rapidly, it produces a cooling effect which freezes the ice cubes and keeps the food cold. Similarly, the sun’s heat pouring down upon the roof of a tropical bungalow can be made to evaporate a refrigerant which can then keep the air inside the bungalow cool.

Another scheme for making direct use of the sun’s energy is to allow it to heat the junction of two pieces of different metals. When this is done an electric current begins to flow in the metals. The current, though small in amount, can ring a bell, light a lamp, or run a motor. The metal junctions are called thermocouples. Some years ago a German scientist, by using several thermocouples, succeeded in keeping an electric lamp lit by sunshine for several months. A French scientist has proposed a plant for connecting together half a million thermocouples.

The junctions would all be exposed to the sun and the ends would be embedded in concrete, so as to keep them at a lower temperature. In this way, huge amounts of electricity would be obtained. Unfortunately, the cost of building the arrangement would be too great as long as there is still enough cheap coal and oil available for generating electricity.

The most likely use of direct sunshine in the near future is the opening up of desert areas. These regions have plenty of steady sunshine. If this almost boundless energy can be caught by some form of solar engine, it can be changed either into the heat energy of steam or into electrical energy. With energy available, many such deserts can be irrigated and transformed into fertile farms and gardens. Excess electrical energy can be sent out to other regions which do not enjoy such intense and steady sunshine.

We spoke of finding sources of energy that do not depend on the sun. Men have dreamed for years of using the power of the tides; and successful experiments have been made. The greatest field for power research today is within the atom. Ceaseless activity goes on inside the atom, and an enormous amount of energy is occasionally developed accidentally when atomic particles collide. Some atoms, as you know, are breaking up and giving off (radiating) energy. Radium is one of these elements whose atoms are breaking up. Other atoms can be made to break up. We call the process atom-smashing. For some years atom-smashing has been going on in laboratories all over the world. Not until 1945 was a way found to employ the energy thus created. This use, as you know, was in the terrible atomic bomb. When we can learn how to harness the enormous energy that is now locked within the atom, we can have all the heat and mechanical power, all the electric power and light that we need. But even then we shall be dependent upon the sun for other things.

The Enormous Heat of the Sun, Our Source of Energy 

The sun is a star some 93,000,000 miles away. It consists of many different layers of gases at a very high temperature. The temperature of the surface of the sun is estimated at about i r,ooo degrees Fahrenheit. This is twice as hot as anything man has been able to devise. The sun’s interior may be ten times hotter. At these temperatures, the molecules in matter break down into the smaller particles called atoms. The atoms themselves undergo change, sending out rays of light and heat. Though these rays travel for 93,000,000 miles before they reach the earth, they can cause a pretty severe sunburn in less than fifteen minutes.

The sun is the basis of our existence and the source of all our usable energy. There are several forms of energy: light, heat, mechanical, electrical and chemical. Each form can be changed into another. The starting point for most of these changes, however, is the light energy which pours down from the sun. You have probably tried to concentrate the light rays of the sun with a magnifying glass or a mirror. The light changes into heat, which can boil water into steam. The steam can turn a small dynamo.

Thus the heat energy is changed into mechanical energy. The dynamo generates electricity, showing how mechanical energy can be changed into electrical energy. Electricity can decompose water into hydrogen and oxygen. This is a change from electrical to chemical energy. Aside from certain kinds of chemical energy and the energy within the atoms of matter, all means for carrying on life activities come to us from the sun.

How We Use Heat Energy to Get Electrical Energy 

The rays of the sun cause the water of lakes, rivers and oceans to evaporate into the air. Later the air moisture condenses and falls as rain, snow or hail. This fills the rivers, which can be dammed so as to store water at a height. When allowed to fall and press against the blades of a turbine or water-wheel, the mechanical energy is changed to electrical energy.

The sun warms the land and the water; but water heats up more slowly than land, and then holds the heat for a longer time. When the land is warmer (during the day) the air over it rises, letting in the cooler sea breezes. When the sea is warmer (during the night) the air over it rises, letting the cooler land air blow toward the sea.

You know that the earth is tilted with respect to its path around the sun. You know that because of this tilt certain regions of the earth receive the direct and concentrated rays of the sun, while other regions receive rays that are slanting and spread thinly over the area. The summer season comes to those parts of the earth which are bathed by direct sunshine, and the winter season arrives where a section of the earth receives the rays slantwise. Regions near the earth’s Equator receive rays that are close to perpendicular during the entire trip. Hence such regions enjoy hot summer weather all the time.

Areas near the Poles never receive direct rays, and have periods when they receive no sunshine. So polar regions are always cold.

The fact that certain areas are always warm and others always cold, sets up huge movements of the air. As the earth spins, these air movements are caused to swerve and give rise to the well-known wind belts. It is in these moving air masses that weather conditions start. In a sense, then, the sun is responsible for our weather. It is the sun’s energy which heats the land, heats the air, causes the air to rise and evaporates the water into the air. Even the electric storms are due to the sun, because evaporation produces electrical charges on the moisture particles and some of the sun’s rays help to increase these charges. We owe to the sun our seasons, our climate and our weather.

Light can stimulate the retina of the eye. The eye lens forms an image on the retina and the brain interprets the stimulus as the picture which we see. Certain chemicals are also affected by light. A piece of photographic film contains small grains of a chemical called silver bromide. This silver bromide is colorless and opaque. (Light can not pass through it.) When light strikes the film, the molecules of silver bromide are changed so as to leave a black silver deposit. This is what happens when a camera lens forms an image n the film. Even when you take a snapshot, the momentary flash of light produces an effect on the silver bromide. The effect is later continued when the film is developed and the picture printed.

Contained in sunlight is a kind of ray called ultraviolet. This ultraviolet light is colorless and invisible to our eyes, yet it makes its presence known and felt. It is very penetrating, and is responsible for sunburn. This can be observed in the effects produced by the mercury-vapor lamp, which is a rich source of ultraviolet light. While direct sunlight can produce a burn in about fifteen minutes, a mercury lamp can cause a similar, or even more serious, burn in two or three minutes. The nature of skin burning or tanning is quite interesting. The action of sunlight on the skin, or of the ultraviolet light contained in sunlight, is to produce a substance called vitamin D on the surface of the skin. The same vitamin D can be produced in foods, such as milk or oils and fats, by exposing them to ultraviolet light. The process is called irradiation. As you know, vitamin D is necessary if our bones are to grow strong, and it is most important to general good health.

It has been shown that ordinary window glass allows most of the sun’s light to pass but blocks the rays of ultraviolet. That is why we are warmed but not burned by the sun in a glassed-in porch, or sun-room. There are special types of glass which permit the passage of the ultraviolet rays. There is room for much further study and improvement in this field.

Every leaf, every blade of grass enjoys a secret which the wisest scientist does not know. For years scientists have been trying to find out how plants make use of sunshine. We know that water and minerals come up from the soil through the roots and stems of plants to the leaves. We know, too, that there are millions of openings on the under surfaces of leaves which let in air containing carbon dioxide. Then, in the presence of a green material called chlorophyl, and while the sun sends down its rays, a chemical action takes place in the cells of the leaves. As a result of this action, carbohydrates are formed and oxygen is released to the air. Carbohydrates—starches and sugars are examples of carbohydrates—are the food which the plant makes for its own use. Then we eat the plants. Thus corn, wheat, fruits and vegetables are the products which plants manufacture with the help of sunshine. They are the food for all animal life, including man. Yet we do not know all we should like to know about the chemical process in the leaf which means so much to our lives.

The Secret of Photosynthesis

It is estimated that one hour of sunshine, falling upon a square yard of leaf surface results in the manufacture of about one gram of carbohydrates. No wonder each plant always turns its leaves so that they catch as much direct sunshine as possible! In an acre of plants there are about two acres of leaf surface. During a summer’s growth, a wheat field may take from the air about eleven tons of carbon dioxide, and with the help of sun energy it will manufacture about seven tons of wheat.

Several scientists have already been able to duplicate the process of photosynthesis on a small scale, in the laboratory. It is as yet too costly for large-scale manufacture. Many are studying the substance, chlorophyl, whose presence is essential to the process. In the Boyce Thompson Laboratory for Plant Research, at Yonkers, New York, some very interesting experiments are now in progress. While the plant’s secret is not yet discovered, some strange results have been obtained.

Marine plant life is also affected by the light and heat of the sun. In the oceans there exists a kind of one-celled plant called the diatom. Diatoms are bacteria of a sort which, with the help of sunshine, can produce the starch needed for their growth. Small marine animals feed on the diatoms. Larger fish feed on the smaller ones, and so on. Thus the sun maintains ocean life.

The heat of the sun also affects all animal life. In the winter time, in the Northern Hemisphere, the sun is closest to the earth. However, since the sun’s rays at this time reach us slantwise and not perpendicularly, little heat can be gathered. This absence of heat and the decrease in amount of sunlight (since the days are short) causes many animals to hibernate, that is, to go into a sleepy state for the winter. Snakes, lizards, frogs, most wild bears, ants and squirrels retire for the winter. If it were not necessary to come out occasionally for food, it is likely that many animals would scarcely be seen during the winter months. As the earth revolves about the sun, and spring arrives, the animals come out of their partial sleep. They become active. Everywhere on the earth animals tend to follow the sun. This is not just accidental. It is necessary for the preservation of their lives.

It is sometimes asked how long could life exist without the sun. Would life suddenly cease, or would there be a gradual decay? As you know, in the far north there is an almost total lack of sunlight for about six months. Does life cease during that time, to be revived with the coming of the sun? No, enough energy is stored away during the dark period to maintain the necessities of life. Animals hibernate and become dormant. Man needs more than just food and shelter. He can not afford to hibernate. Life must go on.

Should the sun fail to make an appearance for a single year the result would be ruinous. Plant life as we know it would vanish and animal life would soon follow.

Is there a substitute for the sun? Can an artificial sun be created? The nearest thing to an artificial sun is artificial ultraviolet light. However, it requires electricity to operate the mercury-vapor lamps, and electricity is dependent upon the sun.

Our debt to the sun is one that can not be repaid. All our lives we are indebted to the sun for food, clothing and shelter. There is only one thing we can do to repay in part this great debt. We can practice conservation. This means saving and not wasting. It is true that the sun’s energy is apparently endless, yet we must learn to take all we need and yet leave some for succeeding generations. In this sense, conservation means careful and purposeful use. Only in this way can we repay partially our debt to the sun.

A German Fairy Tale

Once upon a time, near the borders of a dense forest, there dwelt a poor man who earned his living by cutting wood.

One day, on his way home through the wood, he found a poor little girl who had been carried away by an eagle, and left high up on the branch of a tree to die. He took the little girl home to his wife, and they called her Grethel, and brought her up with their only son, Hansel. But the wife died, and the woodcutter married again. After a little while he became very poor indeed, and could hardly earn enough money to buy bread.

One night as they were lying awake, weak from hunger, Hansel and Grethel heard their stepmother say to their father:

“In a few days we shall die of hunger. If we had only ourselves to keep we might manage to live. I know what we must do. Tomorrow morning we will take the children far into the forest and leave them there.”

“No, wife,” said the man. “How can I have the heart to leave my children alone in the forest for wild beasts to devour?”

But the hardhearted woman talked and talked until the poor man agreed to what she proposed.

Hearing this dreadful plan, Grethel wept bitterly. But Hansel comforted her.

“Do not cry, dear Grethel,” he said; “I will find a way to get home safely.”

He then got up quietly, crept out of the house, and filled his pockets with little white pebbles. At sunrise their stepmother wakened Hansel and Grethel, saying: “Get up, children! We are going into the forest to gather wood”; and she gave them two slices of bread for their dinner. Grethel carried both pieces in her apron, as Hansel’s pockets were full of pebbles.

As they went along, Hansel kept looking back, until at last his stepmother asked him sharply why he kept lingering and looking behind.

“I can see my little white cat sitting on the roof, and I am sure she is crying for me,” said Hansel.

“You stupid!” she replied. “It is only the sun shining on the chimney pot.”

When they reached the middle of the wood their stepmother said: “Run and collect twigs, and we will make a bonfire to keep warm.”

And Hansel and Grethel soon had a blazing bonfire of brushwood. Tired with their long walk, they fell asleep; when they woke up it was dark, and they were alone. Grethel began to cry bitterly; but Hansel said: “We shall be able to find our way home all right when the moon rises, because I dropped a white pebble every time I looked behind this morning.”

When they reached home they were scolded by their stepmother for straying away; but their father was pleased to see them come back safely.

Not long afterward, however, the same poverty came upon them, and the stepmother persuaded her husband to take the children much farther into the wood. The children again overheard the cruel scheme; but Hansel was unable to get a pocketful of stones because his mother bad locked the door. He bravely lingered behind, however, and dropped crumbs from his piece of bread all the way along.

“Why do you lag behind so, Hansel?” said the woman.

“I am looking at my little dove sitting on the roof to say good-bye to me,” replied Hansel.

“Silly!” said she. “It is only the morning sun shining on the housetop.”

Their parents left them when they were asleep, just as before. When they awoke Grethel said: “What are we to do, Hansel, for the night is coming on and we are much farther in the forest than we were last time?” Hansel replied: “Do not fear, dear Grethel; I have left all my bread in little crumbs on the wayside.”

So Grethel dried her eyes and shared her piece of bread with Hansel. When the moon rose they started off; but, to their alarm, they found that there were no crumbs to be seen. The birds had eaten them all up. They wandered about the forest all through the night and the next day, finding only berries to eat; but they could not find their way home, so they lay down and went to sleep.

About noon the next day they saw a lovely snow-whitebird sitting on a branch, and singing so beautifully that they listened to it for a long while. When it had finished singing it flew slowly away, looking round at the children as if inviting them to follow. This Hansel and Grethel did, and after a little while the bird perched on the roof of a tiny house.

To their surprise they found that the walls of this little house were made of gingerbread, the roof of cake and the windows of frosting.

“Oh! Something to eat at last!” cried the hungry Hansel. And the two children pulled pieces of gingerbread off the walls, and ate to their heart’s content. Suddenly came a voice from within: “Munching, crunching, munching,
Who is eating up my house?”

And the children answered: “The wind, the wind, ‘Tis only the wind ‘” and went on eating hungrily.

In a minute or two the door opened, and a little old woman hobbled out.

“Poor little children,” said she. “How tired and hungry you look! Come in with me, and I will give you plenty to eat and drink.”

The children followed her in, and had a meal of milk and pancakes and apples and nuts. And then she put them into two pretty little beds, and they fell asleep.

Now, the old woman was really a bad witch, who had built this gingerbread house to attract children, so that she could capture them and eat them. So when Hansel was asleep she took hold of him and quickly shut him up in an iron cage. Then she shook Grethel, and said: “Get up, lazy-bones, and help me get water and cook some food, for I am going to fatten your brother and eat him.”

After breakfast the old woman went out. Grethel immediately ran and told Hansel all the old woman had said.

“The old woman must be a witch,” said Hansel. “Search for her magic wand and pipe, and then help me out of this cage.”

So Grethel found the wand and pipe, and they ran away together. After some time the old witch came back, and was very angry to find that Hansel and Grethel had escaped. She put on her seven-league boots, and quickly caught up with the children.

As soon as she saw the witch, however, Grethel waved the magic wand, and changed herself into a lake, and Hansel into a swan floating on it. The witch tried hard to entice the swan to the shore by offering him crumbs of bread and cake, but he would not move, so she gave it up and went home in disgust. Grethel then changed Hansel and herself back into their proper forms, and on they went. Next day they saw the witch overtaking them again. This time Grethel changed herself into a rose in a prickly hedge, and Hansel sat on a mossy bank beside it and waited.

The witch soon came up and mounted the bank to pick the rose which she knew must be Grethel. Hansel quickly put the pipe to his mouth and began to play. Now, as it was a fairy pipe, everyone who heard its music had to dance, even the old witch, and there she capered and jigged, till she was fixed firmly into the hedge, where the sharp thorns tore her clothes off and pricked her skin.

Grethel freed herself and the children once more started for home, but, getting tired, they went to sleep in an old hollow tree.

In the morning when they awakened, the sun had risen high above the trees, and it was very hot. Little Hansel said: “Sister, I am very thirsty; if I could find a brook I would go and drink, and fetch you some water too. Listen! I think I hear the sound of one.”

Then Hansel rose up and took Grethel by the hand and went in search of a brook. But the witch had found out all that had happened, and was ready to do them harm. When they had found a brook that ran sparkling over the pebbles, Hansel wanted to drink, but Grethel thought she heard the brook, as it babbled along, say: “Whoever drinks here will be turned into a tiger.” Then she cried out: “Ah, brother, do not drink, or you will be turned into a wild beast and tear me to pieces.”

“I will wait,” said Hansel, “for the next brook.”

But when they came to the next, Grethel listened again, and thought she heard: “Whoever drinks here will become a wolf.”

Then she cried: “Brother, brother, do not drink, or you will become a wolf and eat me!”

So he did not drink, but said: “I shall wait for the next brook; there I must drink, say what you will, for I am so thirsty.”

As they came to the third brook, Grethel listened, and heard: “Whoever drinks here will become a fawn.”

“Ah, brother,” said she, “do not drink, or you will be turned into a fawn and run away from me!”

But Hansel had already stooped down upon his knees, and the moment he put his lips into the Water he was turned into a fawn.

Grethel wept bitterly over the poor creature, and the tears, too, rolled down his eyes as he laid himself beside her. Then she said: “Rest in peace, dear fawn; I will never leave you.”

So she took off her little bead necklace, and put it around his neck, and plucked some rushes and plaited them into a soft string to fasten it, and led the poor little thing by her side farther into the wood.

After they had traveled a long way they came at last to a little cottage; and Grethel having looked in and seen that it was empty, thought to herself, “We can live here.” Then she went and gathered leaves and moss to make a soft bed for the fawn, and every morning she went out and plucked nuts,. roots and berries for herself, and sweet shrubs and tender grass for her companion; and it ate out of her hand, and was pleased; and played and frisked about her. They lived thus a long while in the wood by themselves, till it chanced that the king of that country came to hold a great hunt there. And when the fawn heard all around the echoing of the horns, and the baying of the dogs, and the merry shouts of the hunts- men, he wished very much to go to see what was going on.

“Ah, sister,” said he, “let me go out into the wood. I can stay no longert”

And he begged so hard that at last she agreed to let him go.

“But,” said she, “be sure to come to me in the evening. I shall bar the door to keep out those wild hunts- men; and if you tap at it, and say: ‘Sister, let me in,’ I shall know you; but if you don’t speak, I shall keep the door fast.”

Then away sprang the fawn and frisked and bounded along in the open air. The king and his huntsmen saw the beautiful creature and followed, but could not overtake him; for when they thought they were sure of their prize, he sprang over the bushes and was out of sight in a moment.

As it grew dark he came running home to the hut, and tapped, and said: “Sister, sister, let me in.” Then she opened the little door, and in he jumped, and slept soundly all night on his soft bed of moss.
Next morning the hunt began again; and when he heard the huntsmen’s horns, he said: “Sister, open the door for me, I must go again.”

Then she let him out, and said: “Come back in the evening, and remember what you are to say.”

When the king and the huntsmen again saw the fawn with the beaded collar they chased him; but he was too quick for them. The chase lasted the whole day; but at last the huntsmen nearly caught up with him, and one of them wounded him in the foot, so that he could hardly crawl home. The man who had wounded him followed close behind, and hid himself, so that he heard the little fawn say: “Sister, sister, let me in.” Then the door opened, and shut again. The hunts- man went to the king and told him what he had seen and heard. The king replied: “To-morrow we shall have another chase.”

Grethel was very much frightened whe’i she saw that her dear little fawn was wounded; but she washed the blood away and put some healing herbs on it, and said: “Now go to bed, dear fawn, and you will soon be well again.”

The wound was so small that in the morning there was nothing to be seen of it, and when the horn blew, the little creature said: “I can’t stay here; I must go to look on.”

But Grethel said: “I am sure they will kill you this time; I will not let you go.”

“I shall die,” answered he, “if you keep me here. When I hear the horns, I feel as if I could fly.”

Then Grethel was forced to let him go; so she opened the door with a heavy heart, and he bounded out gaily into the wood.

When the king saw him, he said to his huntsmen: “Now chase him all day long till you catch him; but let none of you do him any harm.”

The sun set, however, without their being able to overtake him, and the king called away the huntsmen, and said to the one who had watched the fawn: “Now come and show me the hut.”

So they tapped on the door, and said: “Sister, sister, let me in.”

Then the door opened, and the king went in, and there stood a maiden more lovely than any he had ever seen. Grethel was frightened to see that it was not her fawn but a king with a golden crown. However, he spoke kindly:
“Will you come with me to my castle and be my wife?”

“Yes,” said the maiden. “But if I do, my fawn must go with me.”

“Well,” said the king, “he shall come and live with you, and want for nothing.”

Just at that moment in sprang the fawn, and his sister tied the string to his neck.

Then the king took Grethel to his palace, and celebrated the marriage in great state. And she told the king all her story; and he sent for the witch and punished her. And the fawn was changed into Hansel again, and he and his sister and the king lived happily together all their days.

The last division of the Tertiary system is known as the Pliocene period. It was during this period that the great land masses of the world took on forms much like those of the present day. Although the seas still covered many areas which are now dry land, the great bodies of water were gradually becoming less and less extensive. This is shown by the limited number of remains of Pliocene sea life which we find stored as fossils in the rocks of the period.

Vast mountain-making movements, which began in the Eocene period, continued during the Pliocene. In Europe, for example, the mighty Alps were still in the process of being formed. In North America the Rocky Mountain region and the eastern part of the continent were being elevated. Many of the famous volcanoes about which we have read, such as Mount Etna in Sicily, show signs of great activity during the Pliocene period. The geysers and bubbling hot springs of Yellowstone National Park are the result of the violent volcanic disturbances that occurred during the Pliocene period.

In a great many ways the animal life of the Pliocene period closely resembled that of to-day. In fact, some of our present-day animals have come down to us from that far-off age almost completely unchanged in form and structure. Hyenas, wolves, bears and bison roamed the countryside. Fleet- footed deer, the hipparion (the three-toed horse), and long-necked camels fled before the ferocious attacks of the sabre-tooth tiger. The hippopotamus, tapir, wild boar and rhinoceros were also present during the Pliocene period. The mastodon, the great elephant-like beast that appeared in the Miocene period, lived on into the Pliocene of Europe and disappeared only late in that age. In America he continued to exist on into the Pleistocene period that followed.

Pliocene deposits have revealed a few scant indications that man may have existed at that time. Among the best known of these remains are those of Pit Izecant hro pus erectus, found in Java in 1891, and Sinanthro pus pekinensis, or Peking man, found in China in 1929. These early men knew how to make fire; and certain stones found with their remains may have been formed into implements of various sort by hand. These stones are known as eoliths, or “dawn stones.” It is not altogether certain that they were worked by hand. They may have been given their shape by purely natural action.

Toward the close of the Pliocene period the climate gradually turned colder and colder, a sign that the next age of the earth’s history was approaching.

This next period, called the Pleistocene, was the first section of the Quaternary, iii which we are now living. It is distinguished by the remarkable climatic changes which occurred, transforming whole continents into fields of ice. For this reason it is often called the Ice Age.

The climate grew colder than it ever had before. The snow fell in great quantities and became packed into vast ice-sheets a mile or more thick. From Canada, Greenland and northern Europe these ice-sheets, or glaciers, slowly spread south. A great ice-sheet covered England, filled the basins of the North Sea and the Baltic, and extended through Middle Europe as far as Silesia, Galicia and Poland. Enormous glaciers filled the Alpine valleys, and descended from the Pyrenees into Spain, while glaciers penetrated even into the heart of France. Practically all of Canada was under an ice-sheet, at least two miles thick in places. In the United States the ice covered New England, New York, northern New Jersey and Pennsylvania, and most of the region between the Ohio and Missouri rivers. In the Far West there was another ice-sheet. The mountainous regions of South America and Asia were also covered.

All Living Things Fled before the Advancing Ice 

Animal and plant life was unable to stand the bitter cold brought on by the glaciers and began to move towards milder climates in the south. It is difficult to imagine plants moving, but they really can if they are given sufficient time. However, it is an extremely slow process.

These arctic conditions passed away and the climate grew warmer. The glaciers ceased to spread over the world.

Plants began to move northward to those lands in which they had once flourished. They were followed by the animals who were dependent upon the plants for their food supply. This climatic change was only temporary, however, and again a period of ice and snow set in. It seems indeed likely that there were several glacial periods separated by intervals of warmer climate; certainly there are indications that the ice and snow alternately advanced and retreated more than once before they finally retired to the North. They left behind them many signs of their great force.

Ice Sheets, Thousands of Feet Thick, Marched Over Europe

In Europe the great distributing centre of the ice and snow seems to have been Scandinavia. From the high table-lands there the ice advanced over Europe in all directions, but the ice-sheet covering Great Britain, though joined with the Scandinavian ice- sheet, was independent, and slid down its own mountains and valleys. In the Scottish Highlands the ice-sheet was tremendous, and filled up valleys and lakes and fords, accumulating to a height of 4,000 or 5,000 feet. Mountains 3,000 feet high, with deep lakes at their bases, show marks of ice up to their summits.

In Canada there seem to have been three separate sheets which ran together, called the Labrador, the Keewatin, and the Cordilleran sheets. All of them came down into the United States.

As all these enormous ice-fields and glaciers moved along they brought about considerable geological changes. Huge masses of moving ice ground up the rocks over which they passed, and converted their surface layers into a mixture of clay, sand and stones known as boulder clay. As they carried the boulder clay along with them the sand and stones acted like great sheets of emery paper, and still further ground down the rocks. The glaciers even scoured over the floors of seas and lakes, and carried shells of shellfish in their further journey overland.

How the Glaciers Carved the Face of the Earth

There can be no doubt that the moving ice-sheets wore down the rocks to a considerable extent. We find everywhere rocks scratched, eaten away, ad polished, and the great masses of boulder clay sugest that enormous destruction occurred. Not only were rocks worn down, but they were often broken off, crumpled and bent by the weight and pressure of the ice. Thousands of lakes in Canada and the United States owe their origin to the ice-sheets. On the other hand, many lakes which existed during the period have now disappeared. The Great Lakes, once larger than at present, are of glacial origin.

When the ice-fields and the glaciers melted they naturally gave rise to streams and torrents whose rushing water continued the work of destruction. The direction of many streams was changed. Many of the waterfalls which now furnish power go back to glacial times. How long since the ice-sheet receded we can only guess. Few scientists think it was less than twenty-five thousand years.

Man and His Struggle to Exist in a Hostile World

Through all these changes man persisted. Flints, tools and skeletal remains are found in Pleistocene deposits, showing that man made great progress during that period. He must have had a hard fight for his life, but he managed to survive. He had to fight not only the glaciers but also the many formidable animals that then roamed the world. In this period the English Channel and the Irish Sea and the North Sea were all dry land and Britain was joined to the continent. The whole of northwestern Europe was overrun with elephants, mammoths, the wooly rhinoceros and the hippopotamus. Bears and hyenas were particularly plentiful in England. There were also great herds of reindeer, elk, bison, red deer and wild horses. All these man must have fought and hunted, and in the caves of the IJordogne Valley in France are found the bones of reindeer, elk, bison and other animals killed and eaten by the cave-men of those days. Even mammoths and bears fell a victim to these early hunters, for their bones are also found in the cave larders.

As man became better acquainted with the world about him, he developed a more advanced culture. Great strides were made in the fields of religion, social organization and the arts. In some of the caves of Spain and France are found remarkably life-like drawings of the animals hunted by early man.

Other drawings hint at religious ceremonies and rituals. On pages 192 and 193 some of these drawings are reproduced.

For tools, weapons and other implements to help him in his daily life, man first used naturally-formed stones found in stream- beds and along the shore. Later he discovered that these stones could be made into more serviceable implements by shaping them artificially. To be sure, his first attempts were crude, but as time went on he learned to become quite expert at chipping beautiful knives, arrow-points, axes and many other useful articles from stone. Still later he learned to polish these implements until they almost looked as though they bad been shaped and finished by modern machinery.

With each forward step, man slowly but surely became master oxer the other animals that had ruled the earth before him for millions and millions of years.

The Pleistocene period shades gradually into what we call the Recent or Human Age, and all the time there have been changes and redistributions of life. The mammoth has disappeared from America, the sabre-tooth tiger has gone, the elephants have departed from Europe. Such changes are still slowly going on. The wolf, among other animals, is doomed to extinction; even races of men are disappearing. Some animals are increasing in numbers and others are changing their haunts and habits. In many cases the march of civilization, more than nature, is responsible for these changes.

The surface of the earth, though in its larger features much the same through the Quaternary, has also been changing. It is changing still; the mountains are still being worn down into the sea, and under the sea new mountain ranges may still be in the process of formation.

Thomas Alva Edison, Inventor

Suppose you are a boy or girl living on a farm remote from town. Only fifty years ago you would have been dependent upon the feeble and uncertain light of candles or kerosene lamps at the coming of nightfall. But now the wonderful electric light is at your beck and call. You have only to reach out your hand and turn a switch, and the room in which you are will be flooded with light. You will be able to read or write and play games by artificial light that rivals even the light of the lordly sun.

Perhaps you may wish to hear a great orchestra or violinist or singer. Your radio may not provide you with what you want, but it does not matter. You have but to select the proper phonograph record, place it on your phonograph or combination phonograph and radio, and soon you will be listening to the magnificent chords of the orchestra or the singing tones of the violin or the superb voice of a great soprano. You may even study a foreign language through phonograph records.

Perhaps it is Friday evening. Home lessons are laid aside, for you are going to a movie in the nearest town. For two hours or more you will be taken to places of interest in your own country or in one far distant; you laugh heartily over a comedy, or your heart aches over some sad, pathetic story. A great parade is held in a distant city, and within a few days the men and women will march down toward you on the picture screen. You see the launching of a proud ship, the forging of a giant anchor, a carnival held in New Orleans or in Rome, or perhaps a native wedding procession in faroff Bombay, or a football game at Yale. Here we are going to read something about the man to whom we owe the fact that our lives are so much richer than the lives of our grandfathers and grandmothers, or even our fathers and mothers when they were young.

Thomas Alva Edison worked out his inventions by known laws of science. He had studied these laws, so that he was able to apply them to make real the visions of his imagination. Yet he had few advantages and little help, and his story is one of those that inspire us to great effort to cultivate the talents that have been given to each one of us.

He was born in February, 1847, in the little village of Milan, in Ohio. His parents were poor because his father did not keep to a settled occupation. Mr. Edison senior had the same kind of mind as his wonder - working son - the kind of mind that is called versatile, that can turn easily from one thing to another. He had not learned, however, that it is wise for a man with a versatile mind to find out how to do one thing thoroughly before he turns to another, and so he was not successful.

Thomas Alva Edison was a quiet, thoughtful little boy, but very inquisitive and always wanting to know how things were done. He was not very strong, however, and was not sent to school until he was quite a big child. When he did go, his teacher, who does not seem to have been very wise, thought him stupid because he asked so many questions. So his mother, who had herself been a teacher, took him away from school at the end of two months and taught him at home. With so kind and loving a teacher he made rapid progress; and above all, he learned to think. His mother had some good books, which he learned to enjoy; and when he was ten years old he read Gibbon’s Decline and Fall of the Roman Empire and Hume’s History of England. About that time he began to study an encyclopedia. It was probably from the encyclopedia that he first learned to take an interest in chemistry and to make experiments.

Edison’s First Sample Laboratory 

By this time his parents, who had moved with him to Port Huron, Michigan, were able to indulge him in his love for making experiments. He bought some books, made a little laboratory in the cellar of his home, and there, by himself, with no teacher, laid the foundation of his knowledge of chemistry.

When he was twelve years old he decided to start out in life for himself, and he became a newsboy on the train which ran from Port Huron to Detroit. Such a newsboy had never been seen before. He was given a corner in the baggage car in which to keep his stocks of newspapers, magazines and candy. To this corner he moved his little laboratory and library of chemical books, and when he was not engaged in his business, went on with his experiments. Still time hung heavy on his hands, and to fill it up he bought a printing-press and type and published on the train a weekly newspaper filled with local news, stories of things that happened on the railway and notes of the markets. The trainmen and passengers were glad to buy the paper from this enterprising young publisher.

An Accident With Sad Consequences

All went well for two or three years. But when he was in his sixteenth year, one day a phosphorus bottle was jarred off one of his shelves and broke on the floor. It set fire to the baggage car, and in his anger at the danger to his train the conductor not only put the boy off the train, but soundly boxed his ears. That was the most unfortunate part of the accident, for as a result of the boxing Edison gradually lost his hearing and became almost totally deaf. His stock was lost, but an act of great bravery and presence of mind on his part brought to his aid a new resource and opened up a new field for him to work in.

He was standing one day on the platform of the depot at Mt. Clemens, Michigan, watching a train come in, when he saw the station agent’s little boy on the track right in front of the oncoming engine. Another moment and the child would have been crushed, but Edison sprang to the track, seized the little one in his arms, and rolled with him to one side, just in time to escape the wheels. To show his gratitude the baby’s father offered to teach Edison telegraphy. The offer was gratefully accepted, and now that his career as a train newsboy was closed, he turned to his new accomplishment as a means of making a living.

First Jobs in Telegraphy

He worked at telegraphy for some years, first in Port Huron, Michigan, thea at Stratford, Canada, and a little later in the western states, and finally in Boston. At the same time he spent all his spare moments studying chemistry and electricity and experimenting on improved telegraph apparatus. It was during these years that he first turned his attention to duplex telegraphy, but through no fault of his own he was unable to sell his invention, and the matter dropped for a time.

In 1869, when he was in his twenty second year, he went to New York. He arrived penniless in the City; but he was a good telegraph-operator, and was fearless of the future. And now a strange thing happened. He applied to the Gold and Stock Telegraph Company for work, and while he was waiting for a reply part of the apparatus broke down. No one knew what was the matter, and everything was in confusion until Edison said he could set the machine at work again. Permission was given him to try, and at the end of two hours, work in the office was going on as if nothing had happened. Edison was asked if he would accept a position at a salary of three hundred dollars a month and, needless to say, he accepted.

Edison Sells His Telegraph Inventions 

In a little over a year Edison sold his telegraph inventions for a large sum of money; this enabled him to set up in business for himself. First he built a factory at Newark, New Jersey, for the manufacture of telegraph apparatus.

He gave up this factory in 1876, and set up a laboratory at Menlo Park, New Jersey. Later this laboratory was moved to West Orange, New Jersey. His chief business now was making inventions. He gave employment to hundreds of workmen and his inventions made him famous the world over.

His first great invention was the quadruplex system of telegraphy.

The First Phonograph is Invented 

It was about the same time that he invented the phonograph. The idea of an instrument which would “write sound” and reproduce it had been thought of before by scientists, though it is doubtful if Edison knew of their efforts to make such an instrument. At any rate, he was the first to make an instrument which would work, and even he did not know that it would work until he heard it repeat the words that he shouted into it.

Edison patented his invention, which from the first excited the wonder of the world. Of course, like all first things, it was crude, and the sounds that it gave back were harsh. For the time he had to lay it aside, for he was busied with many other important projects. But others took it up, and from his parent idea the phonograph and other instruments were invented. Later on, when he had more leisure, Edison himself worked out a phonograph that gave back each beautiful vibration from voice or instrument.

Wonderful Improvements in Electric Lights

When electricity was first used for illumination only large arc-lights were used. The lamps sputtered and scattered sparks, and the light was so harsh that it could be used only for street-lighting and large buildings, such as factories, drill halls and the like. Such a thing as incandescent lights, which make possible the use of softly shaded lamps or indirect lighting in our homes, or brilliant illumination of concert halls and theatres, was not even thought of. For this work Edison put aside the work of his phonograph. He believed that a number of lights could be supplied from one distributing wire, and he believed that the light could be improved so that its use would be a common thing, so he invented the incandescent lamp, from which our modern light.ing has grown. He spent a couple of years over tH work, and to perfect his system improved dynamo machines, and invented a whole scheme of distributing electricity so that it might be used on a large scale for supplying light, heat and power.

Now we come to the moving pictures, where again Edison took up an idea which others had had before him. While it can not be said that Edison invented the moving pictures, he did work out the underlying principle on which they are based, insofar as motion is shown on a screen. The development of “sound” pictures came later and was worked out by others.

Some Other Industrial Inventions

Other inventions of his were hardly less wonderful. He invented the apparatus called the Giant Rolls, by means of which huge rocks could be reduced to fragments in a few seconds. He perfected a new type of storage battery, which did away with the lead and sulphuric acid of the old type. He increased the speed of cement manufacture with his “Long Kiln,” used in burning the mixture of cement material. His new method of cement pouring made it possible to pour the cement for a complete house in a few hours.

When World War I broke out, he found himself in danger of being cut off from his source of supply of carbolic acid for his factories at West Orange. He therefore devised a means of making it for himself. He also erected a number of plants for manufacturing products which formerly had been obtained from Europe.

Artificial Rubber from Goldenrod

During the last years of his life he was busied with the problem of producing synthetic, or artificial rubber. Finally, in 1930, he patented a process for extracting rubber from goldenrod. He died October x8, i9r, at the age of eighty-four.

We have mentioned here but a few of the numberless inventions of this wonderful man. An attempt was made, indeed, to estimate the value of these inventions. When the United States Congress awarded Edison its Gold Medal, it set the value of his contributions to mankind at $15,599,000,000. Any estimate of this sort is futile. It is enouch to say that few men have done so much to make life more complete for countless millions.

Shortly before the death of this great man another important inventor, Henry Ford, established near Dearborn, Michigan, a museum known as Edison Institute. Among the memorials to Edison that it contains is his original laboratory, moved from Menlo Park.

CAESAR (see’-zer)

Gaius Julius Caesar (100-44 B.C.) was the greatest man of ancient Rome. Though he was descended from an old aristocratic family, he was a member of the popular party from his earliest youth.

Marius, the leader of this party, had married Caesar’s aunt; and he took a great interest in the promising youth.

When he was eighteen, Caesar faced mortal danger. Marius was now dead; Sulla, who had been his bitterest enemy, was in power. He demanded that Caesar should divorce his wife Cornelia, the daughter of one of Marius’ friends. Caesar refused; and he escaped the wrath of Sulla only because the Vestal Virgins (see page 3226) pleaded for the lad. “That boy,” grumbled Sulla, as he granted Caesar’s pardon, “will some day be the ruin of the aristocracy, for there is in him many a Marius.”

In 76 B.C. Caesar sailed for the island of Rhodes, in the Mediterranean Sea, in order to study oratory—the art of making speeches. He was captured by pirates off Miletus, in Asia Minor, and kept a prisoner upon the island of Pharmacusa till he was ransomed by his friends. While in captivity Caesar laughingly told the pirates that some day he would have them all crucified. His captors thought it a great joke. But, sure enough, after he was released, young Caesar came back with a powerful expedition, captured many of the pirates and succeeded in carrying out his threat.

When he returned to Rome, he did all in his power to win the favor of the people by means of gifts and entertainments of all kinds. After he had used up his own fortune in this way, he borrowed large sums from the moneylenders of Rome. His efforts bore fruit. He became a great favorite with the people, who elected him to public office again and again.

Caesar had won success as a public leader, but his debts threatened to overwhelm him. So he got the help of his friend Crassus, the wealthiest man of Rome, in arranging for payments to the anxious moneylenders. Caesar was now put in charge of a military campaign in Spain, and for the first time he showed his military genius.
In 6o B.C. Caesar formed a political partnership with Crassus and Pompey, who at that time was considered the foremost Roman citizen. These three men were now all-powerful in Rome; and Caesar had no difficulty in winning election as consul. After serving a year as consul, he was made governor of several provinces, including Gaul (the land we know as France).

In the course of the next ten years he conducted a series of magnificent campaigns in Gaul; he subdued the barbarians who had defied Rome in many parts of that region. While governor of Gaul, Caesar crossed the Rhine River twice and carried the war to the German tribes that dwelt on the other side of that river. He also made two expeditions to England, where no Roman had ever landed before. Caesar has told us the story of his campaigns in his Commentaries of the Gallic Wars, a work familiar to all young people who study Latin.

Caesar’s victories caused Pompey to turn against him, and by 49 B.C. open fighting broke out between the two men. Caesar defeated his rival in the battle of Pharsalia in 48 B.C. and pursued him to Egypt, where Pompey met his death. Caesar remained in Egypt for a time, for he had fallen victim to the charms of Cleopatra, a beautiful Egyptian princess. He even fought a war so that Cleopatra might rule over Egypt together with her young brother.

He then departed for Asia Minor, where King Pharnaces of Pontus was threatening the Asiatic possessions of Rome. Caesar routed the army of Pharnaces in the battle of Zela (47 B.C.). Then he sent the senate a message that consisted of just three words:

Veni, vidi, vici.—”I came, I saw, I conquered.”

Cesar turned his attention next to the remaining supporters of Pompey. The victories of Thapsus (46), in Africa, and Munda (45), in Spain, made him the master of the Roman world. Many people at Rome were now filled with fear and trembling, for hitherto the victors in civil warfare at Rome had generally brought about a reign of terror. But on his return to Rome, Csar pardoned those who had fought against him. Now he ruled alone. His word was law.

We tell you about the achievements of Csar as dictator in our article on the Roman Republic. There is no doubt that he did much for the Roman state. There also seems to be little doubt that he wanted to become king. He had his friend, Mark Antony, offer him a golden diadem, or crown, and he only refused because the people greeted the offer with howls of disapproval. At any rate, Csar determined to keep the supreme power in his own family; he named his grandnephew and adopted son, Octavius, as his successor.

His enemy, Gaius Cassius, formed a conspiracy against him and won the help of Marcus Brutus. Brutus had fought at Pharsalia against Csar, who had pardoned him and showered favors upon him. Brutus joined the conspiraCy against the man who had befriended him because he thought that he would thus help to bring back the good old days of the Roman Republic.

Caesar was attacked by the conspirators in the senate house on the Ides of March (March 15), 44 B.C. He tried to defend himself at first. But when he saw Brutus among those who sought to slay him, he said sadly:

Et tu, Brute? - ”Thou, too, Brutus?”- covered his face with his robe and accepted his fate. He died, pierced by more than twenty wounds, at the foot of Pompey’s statue.

This astonishing man excelled in many ways. He was one of the world’s greatest soldiers, worthy to be compared with Alexander the Great, Hannibal and Napoleon. He was a statesman and lawgiver of the first order. He was greatly esteemed for his eloquence by the Romans. Unfortunately only his Commentaries on the Gallic Wars have come down to us, but he wrote many other works, of which ancient authors speak highly.

ANTONY (an’-toh-nee)

Mark Antony (83?-3o B.C.), whose name in Latin was Marcus Antonius, was an ambitious man, who for a time was master of half the Roman world. He neglected his studies as a youth and wasted his time with gay companions. No one thought that he would ever amount to much.

But when he entered the armies of Rome, he found his real calling. He fought in Syria, Palestine and Egypt and won the reputation of being a brave and energetic officer. He then served under Julius Caesar in Gaul and became his right-hand man. In 50 B.C. Antony went to Rome to serve Caesar’s interests. He was elected as tribune of the people, an important office that carried with it the right of veto over the acts of the senate. As was expected, Antony used his powers to help Caesar’s cause and aroused the anger of the aristocratic party at Rome. He had to flee for his life and took refuge with Caesar in Gaul. He was with that general when he invaded Italy and drove Pompey and his supporters into exile in 49 B.C.

While Caesar was dictator of Rome, he honored Mark Antony greatly. In the year 44 B.C. the dictator was assassinated by a band of conspirators led by Cassius and Brutus. Antony thought it wise to adopt a cautious policy. He soon came to terms with the senate, which backed the conspirators. But when he delivered a funeral oration over Caesar’s body, his eloquence so inflamed the excitable people of Rome that Cassius and Brutus and the rest did not dare remain in the city.

For a time Antony was the most influential man in Rome. But he soon found a rival in Octavian, Caesar’s adopted son and heir, and presently the two men were engaged in open warfare. Then they joined forces. Together with Marcus Lepidus, they formed a triumvirate, or government by three men, in 43. In the following year Antony and Octavian routed the armies of Brutus and Cassius in the battle of Philippi. It was Antony who won the day by his generalship.

Not long afterward Antony became the ruler of all the provinces east of the Adriatic Sea, while Octavian and Lepidus took over the rest of the Roman world. Antony now met the woman who was to become his evil genius. This was the beautiful Egyptian queen, Cleopatra, who in years gone by had won the heart of Caesar. Antony fell madly in love with Cleopatra. He had married Octavia, the sister of Octavian; he now sent her back to Italy while he remained in Egypt in the company of Cleopatra.

From now on he was Cleopatra’s slave. From time to time he would bestir himself and would become again for a while the great general that he used to be. Most of his time, however, was spent in the luxurious court of Cleopatra in Alexandria. Antony forgot that he was a Roman; he assumed the airs and the ceremonies of an Eastern despot. This conduct disgusted some of his Roman friends. They left him to enter the service of Octavian, who now ruled alone over western Rome.

By 32 B.C. Octavian and Antony had broken off relations and they began to prepare for a fight to the finish. At last, one day in September, 31 B.C., the fleet of Octavian faced the combined fleets of Antony and Cleopatra off Actium, in Greece. In the mighty sea battle that followed, Antony and Cleopatra were routed and they had to flee to Alexandria.

In the following year Octavian appeared off Alexandria with a powerful fleet and army. Antony’s fleet and his cavalry went over to Octavian; his infantry was cut to pieces in battle. He now heard a rumor, which later proved to be false, that Cleopatra had taken her own life. In despair Antony slew himself by falling on his sword. He was spared at least the suffering of learning that Cleopatra had tried to betray him and to make peace with Octavian.

CICERO (siss’-e-roh)

Marcus Tullius Cicero (106-43 B.c.) was the foremost orator of ancient Rome. In his youth he studied the law, literature and philosophy with equal zeal. He also tried his hand at soldiering, but he did not distinguish himself. So he gave up all hope of a military career and determined to win fame as a lawyer. He soon became one of the most successful lawyers of Rome. So renowned was his eloquence that the courts were always crowded when it became known that Cicero was going to speak.

The Romans, who always greatly esteemed orators, elected Cicero to a number of public offices, including the highest office of all, the consulship. While he was consul, in 63 B.C., Rome was threatened by a great conspiracy, led by Catiline, a worthless member of the aristocracy. The conspiracy was revealed to Cicero, who denounced Catiline in the senate house in one of the most famous orations of all time.

Catiline managed to make his way out of the city, but some of the conspirators were caught. Cicero had been given great power in order to crush the conspiracy, and he now had five of the conspirators put to death without a trial. Catiline was later defeated in battle and slain.

Cicero was hailed as the Father of his Country by the grateful people of Rome. But after he had become a private citizen again, the fickle Romans forgot the great services that he had rendered to the state. He was accused by his enemies of having had Roman citizens put to death without a trial and he was forced into exile. For several years he remained in exile in Greece. When he returned to Rome, he bowed to the might of the three men who ruled Rome at that time— Caesar, Pompey and Crassus.

In 51 B.C. he had to leave Rome, much against his will, to become governor of the province of Cilicia, in Asia Minor. Unlike most Roman governors of foreign provinces, Cicero proved to be both honest and humane and he won the gratitude of the Cilicians. He was impatient to return to Rome, and as soon as his year of office was over, he left for the scene of his former triumphs.

Soon after Cicero’s return to Rome, civil war broke out between Caesar and Pompey ( B.c.). Cicero did not know which side to support at first. At last he decided tofollow Pompey into exile in Greece. After Pompey’s defeat in the battle of Pharsalia, Cicero went back to Italy and threw himself on the mercy of Caesar, who generously pardoned him. Cicero now retired from public life for a while. He remained in his villa at Tusculum and spent his time writing works on philosophy.

After the assassination of Caesar, Cicero attached himself to Octavian, Caesar’s heir, who had made an alliance with the Roman senate. Octavian was soon openly at war with Mark Antony, who had been Caesar’s friend and supporter. Cicero thought it was perfectly safe for him to turn the full force of his eloquence against Antony, and he attacked him in twelve bitter philippics. (A philippic is an oration full of personal attacks; the name comes from the orations against King Philip of Macedonia by Demosthenes, a famous Athenian orator).

When Octavian joined hands with Antony in 43 B.C., Cicero was doomed; for Octavian consented to Antony’s demand that the great orator should be put to death. Warned of his danger, Cicero was in despair. He fled from Italy in a boat and then returned to his Tusculan villa because the winds were unfavorable. Then he was persuaded to flee again, but this time he was caught by the soldiers sent in pursuit of him, Cicero’s devoted slaves prepared to defend their master to the death, but he forbade them to do so. Wearily he told his pursuers to strike. He was cut down in the sixty-third year of his life.

Cicero was one of the greatest figures in Roman literature. His orations, most of which have come down to us, are the finest example of Roman eloquence. He wrote many works on philosophy, discussing the great problems of life and death in wonderful prose. His letters gave a remarkable picture of one of the most interesting periods in the history of mankind.

AUGUSTUS (aw-gus’-tus)

Augustus (63 B.C.-14 An.), the founder and first ruler of the Roman Empire,was called Gaius Octavius as a boy. He was the grandnephew and the particular favorite of Julius Csar. Since Csar had no sons of his own, he made up his mind that some day his grandnephew would succeed him as ruler of Rome.

Young Octavius went to Spain in 45 B.C. in order to join Csar, who was campaigning against certain followers of his rival, Pornpey. It was at this time that Octavius was formally adopted by Csar. The lad took the name of his granduncle with the added name of Octavianus. So he was now Gaius Julius Csar Octavianus, or Octavian, as he is generally called by historians who write in English.

After Csar’s assassination in March, 44, Octavian came to Rome. In spite of his youth he soon became one of the most powerful men of the Roman state. In our two articles on the Story of Ancient Rome we have told you about Octavian’s career as a Roman leader—how he strove with Cassius and Brutus and, later, with Mark Antony, for the mastery of Rome; how he set up an empire which was to endure for centuries; what he accomplished as the emperor Augustus. (This name, meaning highly honored, was bestowed upon him by the Roman senate).

It has been said that the life of the first Roman emperor was really the life of two men - Octavian and Augustus. In the years when, as Octavian, he was fighting for the rule of the Roman world, he did many mean and treacherous things to bring about his ends. He thought nothing of sacrificing his friends in order to win over powerful enemies. We have told you, in our life of Cicero, how he gave up that famous orator to the vengeance of Mark Antony. In this period of his life he also won a reputation for great cruelty.

But after Octavian became the emperor Augustus, a ruler with no serious rivals, there was a great change for the better. In general he showed a kindness and a generosity that had been almost entirely lacking in former years.

He was sometimes merciful even to those who, like the conspirator Cornelius Cinna, had sought his death.

Though Augustus was the supreme ruler of the Roman state, he was too prudent to take the title of king - a title hated by the Romans. Nor did he assume the outer appearance of a king. He never wore a crown, nor did he ever have a king1y court. To the end of his life he lived like an ordinary Roman citizen. His friends never considered him as a master, but as an equal.

Augustus was not a good general, but he had the happy gift of choosing his officers well. In some of the battles in which he took part it was only the skill of others that won the day after his own bungling had almost lost it. After he became emperor, he left the fighting almost entirely to his generals, who were worthy of his trust.

There was only one serious defeat in his reign—the battle of the Teutoburger Forest, in which three Roman legions, led by Varus, were cut to pieces by the Germans. Augustus could not be consoled when he heard of this disaster. He let his hair and beard grow and often cried out in his grief: “Varus, Varus, give me back my legions!”
It is true that by setting up a government in which one man was all-powerful, Augustus paved the way for such wicked emperors as Caligula, Nero and Domitian. But his own reign was a prosperous and happy one, and he was proud of his achievements as emperor. On his deathbed, he turned to those who were standing about him and said: “If I have acted well my part in life’s drama, greet my departure with your applause!”

MAECENAS (meh-see’-nas)

When we speak of a patron of art—a man who helps artists and men of letters and musicians—we often say: “He is a Maecenas.” This Maecenas was a real person, who flourished at Rome in the last days of the Republic and the early days of the Empire.

Gaius Cilnius Maecenas (7o?-8 B.C.) was a member of a respectable old Roman family, which claimed descent from the old kings of Etruria, in central Italy. He was a wealthy man and a cultured one, with a deep knowledge of Latin and Greek literature. While still a young man he became an intimate friend of Octavian, the grandnephew and adopted son of Julius Cesar. After the assassination of Caesar in 44 B.C. Octavian became one of the most important men of Rome. Maecenas was his most trusted adviser.

It is said that Maecenas had a good deal to do with the establishment of the Roman Empire. After Octavian had crushed Mark Antony and had become the sole ruler over Rome, he did not know whether or not to restore the republican form of government. He summoned two of his oldest friends, Maecenas and Agrippa, and asked them what they advised.

Agrippa was all in favor of the republic. But Maecenas reminded Octavian of the evils that the republican form of government had brought to Rome. He claimed that Octavian could bring about peace by setting up a monarchy—a permanent form of government that would not be changed at the whim of the fickle Roman public. Octavian took the advice of Maecenas. He became the first emperor of Rome under the name of Augustus.

For a few years Maecenas continued to enjoy the favor of the Emperor, but then, for some unknown reason, the relations between the two men cooled. After 21 B.C. Maecenas took no further part in public life. He spent most of his time in his magnificent villa on the Esquiline Hill, in the city of Rome. This villa was a favorite meeting-place for all sorts of people—statesmen, men of letters, artists, musicians, actors and clowns.

Some of these guests were vulgar people, whose only merit was that they made their host laugh. But Maecenas did not permit them to become intimate with him. He reserved his friendship for men of talent. His particular favorites were Virgil and Horace, the greatest poets of that day.

Maecenas used his influence to help Virgil recover his farm, which had been taken from him by the government.

He showered even greater favors upon Horace. He got a pardon for him for having fought against Octavian at Philippi in 42 B.C. Later Maecenas gave Horace a farm in the Sabine district near Rome - a farm that was made immortal in Horace’s odes. Nor did Maecenas ever make any demands on the poet. The relationship between them was always that of two intimate friends of equal rank, though Mcenas was a man of distinguished family and Horace was the son of a freedman - a man who had once been a slave.

Maecenas wrote a good deal himself - both prose and poetry - but very little of what he wrote has come down to us. This is no great loss, to judge by the fragments which still exist. Like many other people, Mcenas was an excellent critic of other men’s writings, but could not write well himself.

MARCUS AURELIUS (oh-ree’-li-us)

The great Greek thinker Plato once wrote that men would enjoy a perfect form of government only when a philosopher became a king or when a king became a philosopher. For a philosopher is a man who is interested in the eternal problems of life and death; such a man would not care for personal glory and gain, but would seek only the happiness of his subjects. In the year 161 A.D. what Plato longed for actually came to pass; for a philosopher became the emperor of Rome. He was Marcus Aurelius Antoninus (12 i-8o), or Marcus Aurelius, as he is generally known.

His name as a boy was Marcus Annus Verus. From his early childhood he studied the works of Latin and Greek literature and philosophy with great enthusiasm. He was particularly inspired by the writings of the Greek Stoic (stoh’-ik) philosophers. The Stoic sect had been founded by the Greek Zeno in the third century B.C. The name Stoic came from a famous stoa, or porch, where the Stoics of Athens used to teach. A hundred years before Marcus Aurelius, Seneca, the wise old philosopher and writer who was tutor to Nero, was a famous Roman Stoic.

The Stoics held that a wise man should not allow himself to be influenced by either joy or grief; he should willingly accept all that was in store for him.

Furthermore, he should lead a frugal life, shunning all luxury in food and clothing. The Stoics had a very stern idea of duty, too. They thought that a man should do his assigned task without any thought of reward either in this world or in the world to come.

The Stoics, as you see, had a rather forbidding faith, which certainly would not attract most children. Yet as a mere boy of twelve Marcus became a Stoic and from that time he faithfully obeyed all the Stoic teachings. He continued his study of philosophy and attracted much attention at Rome as a lad of great promise.

The emperor Antoninus Pius adopted Marcus as his son, and he became known thereafter as Marcus Aurelius Antoninus. He was the Emperor’s trusted companion and adviser; and when Antoninus died, in 161, Marcus Aurelius followed him upon the throne.

In our article on the Roman Empire we tell you about his achievements as a ruler. He continued to be a Stoic to the end of his days. Even when he was the master of a great part of the civilized world, with all the
luxuries of the Orient his for the asking, he lived simply and dressed in plain garments. And he gave himself up with all his heart and soul to what he realized was his duty— watching over the interests of his millions of subjects.

In his spare time the Emperor wrote down in a diary the serious thoughts that came to him concerning the meaning of life and the way it should be lived. He so loved the Greek philosophers who had converted him to the Stoic belief that he wrote this diary in the Greek language. After a while it came to contain a fairly complete summing up of the Emperor’s Stoic faith.

The Emperor gave the name “To Himself” to this diary of his. There is no reason to believe that he ever meant it to be read by anybody but himself. But, under the name Meditations of Marcus Aurelius, it became one of the most widely read works of Greek literature, second only to the New Testament in popularity. It is perhaps the noblest monument of pagan thought.

It is sad to record that this great man was an enemy of the Christians. Some people think that he was influenced by the Stoic philosophers who were his constant companions and who were jealous of a faith that was robbing them of many followers. However that may be, Marcus Aurelius believed, as did many people in his day, that the Christians were secretly planning to overthrow the Empire. He thought, therefore, that his duty as emperor made it necessary for him to treat them with great severity.

The Romans mourned deeply at the death of Marcus Aurelius. Yet they could not think of him as a mortal man who had passed away. They thought rather that he had been sent down from heaven for a time in order to bless mankind and that he had now returned to Heaven. He was worshiped as a god after his death. For many years to come the image of the Emperor was to be found among the household gods of almost every Roman family that still remained faithful to the ancient pagan beliefs

We have learned that there are three methods for transferring heat energy, namely: conduction, which takes place mainly in solids; convection, which takes place mainly in fluids, either gases or liquids; and radiation, which applies to the transfer of energy through space.

Conduction

The knowledge of these principles and the application of them are very important to our everyday life. In heating and cooling our homes, offices and factories, and in cooking food, we are interested in methods of transferring heat from one place to another. In other cases, such as in the use of refrigerators, we are mainly interested in preventing a transfer of heat. In other words, we control the transfer of heat so that we can get it to a place where it is needed or keep it out of places where it is not needed.

You already know that if you hold one end of a poker while the other end is placed in a bed of live coals, within a few minutes the entire poker becomes hot. The molecules of the hot coals are in very rapid vibration. The molecules of the iron poker which are near the coals receive some of this energy of vibration and in turn transmit this vibration to their less active neighbors. These transmit energy to the next molecules and so on, until the whole poker is heated. In no case does one molecule from the live bed of coals move along the poker to your hand; the molecules of a solid are held in the same positions with respect to one another. Only the vibrations are communicated along the poker.

Silver is the best conductor of heat known, copper is next, and gold and aluminum are not very far behind. Metals are much better conductors than other substances.

Feathers, fur, straw, wool and cork are poor conductors of heat. Liquids and gases in general are very poor conductors. A very poor conductor is called an insulator. The poor conductivity of such things as wool, fur and so on, is chiefly due to the fact that they contain such large air spaces. Substances which contain a large number of small air spaces are in general poor conductors.

We see therefore that substances differ widely in their ability to conduct heat. The following simple experiment will prove this point. Twist the ends of two thick wires of iron and copper together. Place some wax on the end of each wire and heat the twisted part in a flame. In a few minutes you will notice that the wax at the end of the copper wire will melt first. This proves the superior conducting power of copper.

If you have ever stood barefooted, on a tile floor, you know that your feet feel much colder than when you stand on a rug in the same room. Heat from your feet is quickly conducted to the tile. This proves that the tile is a better conductor of heat than the rug. You probably know that most modern cooking utensils are made of copper or aluminum; and now you know the reason why. They conduct well the heat from the stove to the food that is to be cooked.

Insulators

Many materials are useful, not because they are good conductors, but because they are poor conductors. Our woolen winter clothing, for instance. Air is a much poorer conductor of heat than wool and since there are many air spaces in wool, this material is one of the best heat insulators known. Wool clothing does not actually give us any warmth in winter; it prevents the heat of the body from escaping. Clothing made from the poorest conductors is “warmest.” Several light sweaters are warmer than one heavy sweater because there is a layer of non-conducting air between each two. The warmth of a fur coat is much appreciated by women, but its beauty is apparently appreciated more. If it were not so, fur coats would be worn with the fur on the inside instead of on the outside. Linen and cotton conduct heat twice as fast as wool and are therefore more suitable for summer clothing. On cold winter nights fowls on the roost spread their feathers to increase the size of the air spaces. A pad of flannel is good for lifting hot pans, and a wooden handle is put on a soldering iron because flannel and wood are poor conductors. Glass is also a poor conductor of heat. When hot tea is poured into a glass it is liable to crack because the inside of the glass gets heated first and expands, while the outside has not yet been heated—unless a good conductor, such as a metal spoon, is put into the glass to conduct the heat away.

The walls and doors of your refrigerator contain materials which are poor conductors of heat, such as sawdust and cork. They keep the heat of the room from being conducted into the refrigerator. While we are on the subject of refrigerators, it may be interesting to point out that they were an important part of the equipment of polar explorers. Can you tell why?

Furnaces and hot-water pipes are covered with asbestos or magnesia prepared in a form so as to contain a great number of air spaces. These substances will withstand high temperatures and are poor conductors of heat; so the heat is not wasted by leaking out through the walls of the furnace, or the pipes. Houses are built with double walls and sometimes with double roofs and double windows. The air spaces between the walls keep the heat from escaping in winter and the outside heat from coming in during the hot weather. Thus the house is warmer in winter and cooler in summer. We say such a house is well insulated. A well-insulated house needs less fuel than one that is not insulated.

Advertisements in newspapers and magazines now call your attention to many kinds of insulating materials that are used in the construction of houses.

Convection

We often warm our hands by holding them over a radiator or stove. Heat is carried from the stove or radiator to the hands by a stream of air. Thus we see that warm air is streaming upward from the source of heat to some colder place. The reason for this is that substances expand when heated, and their density is correspondingly decreased. This means that air over a heated surface is less dense than the surrounding air. The colder, heavier air will displace this lighter air and push it upward. Such convection currents may be produced in either liquids or gases. Ordinary ventilation depends upon convection. Air which is exhaled (breathed out) from your lungs is warmer and lighter than the cold air in a room. If the window is open at the top, this warm, used air will escape out the window, pushed up by the colder air which comes in from nearer the floor.

The hot gases in a ‘chimney are lighter than the air outside and the effect we call the draft is due to the greater pressure exerted by colder air. The speed with which the air is forced up the chimney depends in part on the difference in weight between the column of hot gases in the chimney and a column of outside air of the same height and cross section. The hotter the gases and the taller the chimney, the greater the draft.

This accounts for the tall chimneys constructed for factories. A stack built for smelting copper ores in Montana is 580 feet high.

A cheap and convenient heating system for a house is found in the hot-air furnace. This system consists of a stove with a jacket about it from the top of which pipes lead to the rooms to be heated. Through the pipes air is pushed up by convection currents.

Cold air is led into the base of the jacket where it is heated, in turn, and pushed up into the pipes by the colder air behind it. The cold air in each room is forced out through openings near the floors. In many of the more modern homes convection alone is not relied upon for the circulation of warm air. An electrically operated fan or blower circulates the air by pushing it through. In such cases the air is made to pass through a pad of loosely woven felt or other fibrous material to take out dust and smoke. Such systems are commonly referred to as air conditioning.

Land and sea breezes are also caused by convection. The land has a lower specific heat than the water. In other words, the land heats up more quickly than the water but it also loses its heat more quickly. Therefore during the daytime the land has a higher temperature than the water. The air over the land is pushed upward by the cooler air from the sea. About noon a cool sea breeze begins to blow toward the land. At night, the reverse is true; that is, the land cools more quickly, going below the temperature of the water. The warmer air over the water is forced upward and the winds consequently blow offshore, from the land toward the water. This is commonly known as a land breeze. For these reasons fishermen along the coast go to sea at night with the land breeze and return in the forenoon with the sea breeze.

In steam-heating systems, water is heated to boiling and the steam, which occupies about i,óoo times as much volume as the water had occupied, expands through the pipes and into the radiators. It is distributed by its own pressure throughout the system. When the steam reaches a radiator in a room, the cooler air outside the radiator causes the steam to condense, because heat must flow from a higher heat-level to a lower heat-level—from a hotter thing to a cooler thing. As enough heat leaves the steam, the steam becomes water; it condenses. As the steam condenses in the radiator, each gram sets free 540 calories of heat; this much heat was added to the gram of boiling water in order to convert it to steam. The heat from the radiators is distributed to the room by convection and by radiation. After condensation the water at a temperature below xoo degrees Centigrade returns to the boiler, usually through the same pipe. This process is repeated as long as the boiler produces steam.

Radiation

We have already spoken briefly about the process of transmission of energy without the aid of intervening molecules—radiation. If you stand before an open fire you are heated. Since the air is a non-conductor, you do not receive this heat by conduction. Since convection carries the heated air upward, you do not get the heat by convection. The energy must be transmitted to you by some other method. Heat comes to us from the sun across millions of miles of space where there is no material in which conduction or convection can take place. In such cases the heat is called radiant heat. Radiant heat may pass through objects without heating them. Energy, or radiant heat, from the sun passes through the upper layers of the earth’s atmosphere without heating them.

Glass permits short waves of radiant energy from the sun to penetrate, but not longer waves like those of a flame. If a pane of glass be held before a gas flame, it will transmit only a little of the heat and will become very hot because it has absorbed much of this heat. The reason is that the flame emits long waves. The sun’s heat, however, passes readily through a glass-enclosed greenhouse; yet the heat from inside the greenhouse can not escape through the glass. Heat comes from the sun through the atmosphere without heating it. The short waves from the sun can penetrate the atmosphere, but when they strike the earth they are absorbed and warm it up.

The earth radiates longer waves which are mostly absorbed by the surrounding atmosphere. If the atmosphere were not present, we would burn to death during the day and freeze to death at night. This is one of the reasons why life can not be maintained on the moon, which does not have a thick blanket of atmosphere. Orange-growers in Florida and California protect their crop from sudden frost by burning smudge pots. These smoky fires are built for the purpose of providing a layer of smoke which absorbs radiation from the earth, and thus provides a sort of extra blanket.

Absorption and Reflection of Heat

Have you ever wondered why light-colored clothes are worn in summer, or why the Arabian horses are white?

Surfaces differ in their ability to absorb radiant heat. Polished materials are good reflectors of heat; hence they are poor absorbers. Clean snow is a good reflector; hence it will not absorb much heat. This accounts for the fact that the snow in the country does not melt so rapidly as the snow in the city. In the city the snow gets dirty more rapidly and it melts faster. All black substances are found to be good absorbers of heat. Lay a black cloth and a white cloth in the sun on a cold day. In a short time you will find that more snow has melted under the black cloth than under the white cloth. The black cloth has absorbed more heat, and ha in turn, radiated more heat, and so melted the snow more quickly. Can you now see why light-colored clothes are worn in the summer? The Arabians use white horses because in that hot country dark-colored horses would more easily be exhausted from heat. A good absorber of heat is also a good radiator of heat; and a poor absorber of heat is a poor radiator of heat.

Refrigeration

In many homes a gas flame is used directly to produce ice in a refrigerator while in others an electrical motor is used. In either type of refrigerator we have one of the most interesting examples of repeated transmissions of energy. In the second type, the electric refrigerator, the energy of burning fuel is transformed into electrical energy at the power house; this energy is changed by means of a motor to mechanical energy y operating a pump which in turn compresses a gas until it liquefies. The heat produced when this gas is compressed is carried away by running water or by the circulation of air. We choose a gas which liquefies easily such as sulphur dioxide or the new commercial preparation “freon.” The cooled liquid then evaporates through a valve with a small opening into coils of pipe in the compartment of the refrigerator where the ice cubes are kept. The pressure in these pipes is kept very low by the pump which acts both as an exhaust pump and as a compressor. In order to evaporate in the coils the liquid must have heat energy supplied to it. The only place heat energy can come from is the food and if the food gives up this heat energy, it will be cooled. Thus we see that to evaporate, the liquid must take heat from the food.

Most of us are familiar with the cooling effect of evaporation. You have often heard swimmers say that it is warmer in the water than out of it. This should not be surprising to us if we understand the principles of evaporation. When you come out of the water, your body is wet and water evaporates from it. The heat necessary to vaporize the water is taken from the body, leaving the body cool. Some liquids evaporate even faster than water. If a little alcohol or ether is poured on the hand and allowed to evaporate, your hand will become cooled. Every molecule that evaporates from your hand must take enough heat away from it to give it sufficient energy to leave your hand. Only the fast-moving alcohol molecules will escape, leaving the slower ones behind. As you already know, slow-moving molecules in a liquid mean low temperature. In the summer-
time people use electric fans for the sole purpose of evaporating the moisture from their bodies at a faster rate. This evaporation takes heat from their bodies.

Converting Heat to Work

Heat energy can be converted into mechan a1 energy by means of a machine called a heat engine. For example, if we boil water in a covered pot, we may notice the cover moving up and down. When sufficient heat energy is added to the water molecules they are converted into a gas—steam—and the pressure of the steam against the cover is sufficient to raise it. This is a crude but simple example of how we convert heat energy into mechanical energy. With this principle in mind let us devise a simple ideal steam engine just for the sake of understanding the principle of operation. Watt, the inventor of the steam engine, probably went through the same reasoning process. If we allow steam from the boiler to enter inlet i, it will enter the cylinder and push the piston to the right as shown in diagram i. Now if we close inlet i and open inlet number 2, the expanding steam will drive the piston to the left provided that outlet r is open for the spent steam to escape. If now inlet 2 is closed and inlet i is open, the steam will expand against the piston and drive it to the right provided that outlet 2 is open. Outlet x must, of course, be closed, otherwise a pressure will not be built up against the piston. In this ideal model of steam engine everything would work fine if all the inlets and outlets were opened and closed at the right time. In a real steam engine the opening and closing of the inlets and outlets, called valves, is entirely automatic.

The principle of the modern steam engine is based on the ideal engine we have just described. The steam chest, contains an ingenious device called a slide valve, that slides from one end of the box to the other. Its purpose is to uncover the inlets, or ports, which allow steam to pass either to the right-hand or left-hand side of the piston, P. (The piston slides in the cylinder) Since the slide valve, must move left and right, it is connected to an eccentric on the shaft of the flywheel through a rod. Steam flows from the boiler through the pipe, into the cylinder, and exerts a force, pushing the piston, to the left. As the piston moves, it turns the shaft by means of the driving rod and a crank. This in turn moves the eccentric rod which causes the slide valve to move to the right. When the piston has moved about one-third of its stroke, the slide valve closes the port. The steam is now trapped in the cylinder and continues to expand, driving the piston forward. When the piston reaches the left end, the slide valve has moved far enough to the right to admit fresh steam through the port and to open the right end of the cylinder through to the exhaust port.

The piston is then pushed back toward the right, which in turn forces the cool steam in the right end out of the exhaust port. As the piston moves back and forth, the slide valve also moves back and forth. First it admits steam into one side of the cylinder and then into tile other, at the same time opening one exhaust port, and then the other. This back-and-forth motion of the piston, known as reciprocating motion, is changed to a rotary motion of the shaft by a connecting rod and crank. Actually the inlet ports opening to the steam chest are shut off before the piston reaches the end of the stroke, and the piston is driven the remainder of the way by the expansion of the steam trapped in the cylinder. The inertia of the heavy flywheel steadies the motion of the crankshaft and insures constant speed of rotation.

As Sindbad the Sailor was sitting in the mansion which he had built in the city of Bagdad, he heard a poor porter say: “Men are not rewarded according to their merit. I have worked harder than Sindbad, and yet he lives in splendor and I live in misery.”

Sindbad was moved by the porter’s complaint and invited him to come in and listen to the story of his adventures.

“Perhaps when you have learned by what sufferings I won my wealth,” said Sindbad, “you will be more contented with your own lot in life.

“Look at my white hair and worn facet I seem an old man. But how young and strong I was when I sailed away to make my fortune by trading in strange countries! Soon after we departed, our ship was becalmed near a small island, but when we landed to look at the place, we found that what we had taken for land was only the green back of a great beast, a sort of ocean cow, called a whale.

“No sooner had we landed than it began to sway to and fro, and then it plunged beneath the waves and left us struggling in the sea. Clinging to a large piece of wood, I was washed ashore on a desert island.

“Here I thought I should have starved. But on wandering about I found a clump of fruit trees and hidden among them a great white ball about fifty feet in size. By this time I was very weary, and so when I had eaten some of the fruit I crept beneath the ball and lay down to sleep. Just as I was closing my eyes I looked up and saw that the sky was darkened by the wings of a gigantic bird.

“‘Good heavens!’ I exclaimed. ‘This great white ball is the egg of the monstrous bird that sailors call a roc.’

“And so it was. The roc settled on the egg under which I was lying, and one of its claws, which was as big as the trunk of a tree, caught my dress.

“At daybreak the roc flew up into the air and carried me to such a height that I could not see the earth. Then it descended with such speed that I nearly lost my senses. As it alighted I freed my dress and found myself in a deep valley cut off from the world by a circle of high, steep mountains.

“It was the Valley of Diamonds! The grouQd was covered with precious stones. Full of joy, I began to fill my pockets with them, but my joy was soon turned to terror. The valley was haunted by great serpents, and I could find no means of escape.

“I crept into a cave and blocked up the opening with a large stone, but all night I was kept awake by the hissing of the serpents. At daybreak they retired, as they were afraid of the roc that used then to visit the valley in search of food. Then I stole out of the cave, only .to be knocked over by something that came tumbling down the mountainside. It was a great piece of fresh meat. As it rolled along, the diamonds on the ground stuck to it. Looking up, I saw on the mountains a band of men, who were preparing to roll another piece of meat into the valley.

“‘I have heard of this means of getting diamonds,’ I said to myself. ‘It strikes me that it is also a good means of getting away.’

“So I tied myself to the piece of meat and hid beneath it, and presently an eagle swooped down and seized the meat and carried it to its nest on the top of the mountains. The band of men drove the eagle away, and turned the meat over to pick off the diamonds that had stuck to it, and found me tied to it.

“When they had all the diamonds they needed, we sailed for home. But on passing the desert island my companions landed with an ax and broke open the great white ball. A terrible scream rang through the sky. The roc had seen them. They rushed back to the ship, and we quickly sailed away; but the roc followed us, bearing in its claws a great piece of granite. This it dropped on our ship, and down we all went into the sea. Holding on to a fragment of wreckage with one hand, and swimming with the other, as the sea was calm, I managed to reach another island.

“It was a delicious spot! Sparkling streams ran between vineyards full of grapes and orchards full of fruit.

There I met a strange old man, who made signs to me to carry him over one of the streams. As soon as I hoisted him on my back, the old man threw his legs over my neck and squeezed my throat so that I fainted. When I came to, he was still fixed on my shoulders. And there he remained.

“He made me his slave. When, in order to keep up my strength, I made some wine out of the grapes, he took it from me and drank it all up. Happily, it was too strong for him, and releasing his hold of my neck, he fell to the ground, and I killed him.

“By the shore I met some sailors, with whom I returned to Bagdad.

“‘That was the Old Man of the Sea’, they said to me. ‘You are the first person that has escaped from being at last strangled by him.’

“Now don’t you think,” said Sindbad to the porter, “that I have earned all the riches that I brought away from the Valley of Diamonds?” The porter agreed that he had.

Once upon a time there lived a king and .1 queen who had no children, and this was a great sorrow to them. But one day as the queen was walking by the side of the river, a little fish lifted his head out of the water and said, ‘Your wish shall be fulfilled; you shall have a daughter.”

What the little fish had foretold soon came to pass, and the queen had a little girl whom they called Brier Rose. She was so beautiful that the king, in great joy, determined to hold a feast.

He invited not only his relations, friends, and neighbors, but also all the fairies that they might be good to his little daughter.

Now there were thirteen fairies in his kingdom, and he had only twelve golden dishes, so he was obliged to leave one of the fairies without an invitation. The rest came, and after the feast was over, they gave their gifts to the little princess. One gave her virtue, another beauty, another wisdom, and so on till she had all that was excellent in the world.

But just as the eleventh fairy had done blessing her, a great noise was heard at the door, and the thirteenth fairy stormed in, very angry that she had not been invited.

“Here is my gift!” she cried. “The princess shall in her fifteenth year be wounded by a spindle and fall down dead!” Then she rushed out again, not knowing that the twelfth fairy had not yet spoken.

Now the twelfth fairy came forward and soothed the weeping queen.

“I can not promise that the wish of the thirteenth fairy shall not be fulfilled,” she said, “but I can soften it. Your daughter shall not die, but will fall asleep for a hundred years.”

But the queen would not be comforted. “Only say that we may sleep with her!” she begged. And the twelfth fairy said this might be done.

The king called all his soldiers to him. “Search the kingdom,” he ordered. “Buy up and destroy every spindle. Let not a single one be left in all the land.” And he commanded that the princess be guarded day and night, so that never, till she passed her fifteenth birthday, should a spindle come near her.

As the years passed, the fairies’ gifts were all fulfilled. The princess was so beautiful, well-behaved, amiable and wise that everyone loved her.

Now it happened that on the eve of the day Brier Rose was fifteen years old, a birthday feast was prepared for her, with great rejoicing in all the land, for the king and queen felt that the danger was now over. Everyone was busy hanging garlands in the palace or preparing the feast, and for a few minutes in the afternoon no one was with the princess. She roved about, well pleased to be alone, and she came at last to an old tower to which there was a narrow staircase. Upstairs there sat an old woman spinning away busily.

“How now, good mother,” said the princess, “what are you doing there?”

“Spinning,” said the old woman.

“How prettily that little thing turns around!” said the princess. “I wish I might try it.”

“Take it then,” said the old woman.

The princess sat down and took the spindle and began to spin. But scarcely had she touched it when she fell down on the floor as though dead.

However, she was not dead, but had only fallen into a deep sleep.

Immediately the king and queen fell asleep too. And the horses slept in the stables, and the dogs in the court, the pigeons on the housetop and flies on the walls. Even the fire on the hearth left off blazing and went to sleep, and the meat that was roasting stood still.

The cook, who was at the moment pulling the kitchen-boy by the hair to give him a box on the ear for something he had done amiss, let him go, and both fell asleep. And so everything stood still, and slept soundly.

A large hedge of thorns soon grew round the palace, and every year it became higher and thicker till at last the whole palace was surrounded and hid, so that not even the roof or the chimneys could be seen. But there went a report through all the land of the beautiful sleeping princess, so that from time to time several king’s sons came and tried to break through the thicket into the palace. This they could never do, for the thorns and bushes laid hold of them as if with hands, and there they stuck fast.

Now on the day that the hundred years were completed, a prince came to the thicket. He saw no thorns, as he had expected; he saw nothing but beautiful roses and flowering shrubs, through which he passed with ease, and they closed after him as firm as ever. He came at last to the palace, and there in the court lay the dogs asleep, and the horses in the stables, and on the roof sat the pigeons fast asleep with their heads under their wings. And when he came inside the palace, the flies slept on the walls, and the cook in the kitchen was still holding up her hand as if she would box the ears of the kitchen-boy, and the maid sat with a black fowl in her hand ready to be plucked.

Then he went on still farther, and all was so still that he could hear every breath he drew; till at last he came to the old tower and opened the door of the room in which the princess lay. There she was, fast asleep. She looked so beautiful that he could not take his eyes off her, and he stooped down and gave her a kiss. The moment he kissed her, she opened her eyes and smiled upon him.

Then the king and queen awoke, and all the court. The horses got up and shook themselves, and the dogs jumped about and barked; the pigeons took their heads from under their wings and looked about and flew into the fields; the flies on the walls buzzed away; the fire in the kitchen blazed up and cooked the dinner, and. the roasting meat turned again. The cook gave the boy the box on his ear so that he cried out, and the maid went on plucking the fowl.

And then was the wedding of the prince and the princess celebrated, and they lived happily together all their lives long.