steady, intense, dependable heat for such purposes are not located so as to serve great masses of the world's present population. Of course, the hot deserts are the places of dependable sun's heat, but these are poor places in which to live.

Very likely we shall depend upon the winds more in the future than we do to-day. They are, of course, uncertain. Not until they have been harnessed up with some device for storing their power will they be dependable servants. However, as coal be

Courtesy of Gibson: The Romance of Scientific Discovery AREAS SUITABLE FOR SOLAR ENGINES

Can you recognize these areas from your study of geography? Are they areas of dense population?

comes dearer, it will not be surprising if man turns his energies to the more effective harnessing of the winds.

We have a power resource, too, in plant life. Only to a slight extent will such power come from burning the wood of our forests; the wood would not go far and will be needed for other purposes. We shall perhaps get power through the ability of our chemists to procure alcohol and vegetable oils from plants. How great use will be made of such power resources in later centuries we have, of course, no means of telling at this time.

Our civilization is a civilization built upon power. We have seen enough of our power resources to disquiet us concerning the possibility of our living together well in a far-distant future,

unless we become able to command power resources not being used to-day. If we become able to do this, it will be through the growth of scientific knowledge.

Harnessing the Atom. Can the scientists come to our rescue? There can be little doubt that they will steadily improve our existing powers. Will they be able to harness powers of which we are not dreaming to-day? Of course, no one can answer such a question as that and be certain that his answer is correct. However, since we all like to wonder about things which may happen, and since the achievements that scientists have already made are quite as wonderful as any of the stories in Arabian Nights, let us see what it would mean if scientists should, some day, learn to harness the atom and make it work for us.

We know that everything, whether solid, liquid, or gas, is made up of little particles which we call molecules. These molecules, even in solids, are always in violent motion, rushing about, colliding, and rebounding in every direction. Pull a coin out of your pocket and look at it. It seems very quiet. As a matter of fact, there are in it trillions of molecules dashing about. The coin is just one huge reservoir of energy. Or, notice the air on a still day. There seems to be no motion in it; yet each molecule in that air is dashing about at a rate faster than that of a rifle bullet and is colliding about five billion times a second with other molecules. These molecules are so exceedingly small that more than a hundred million of them side by side would reach only an inch. This does not mean much to us until we remember that that number is about as large as the population of the United States to-day. As many people as that, placed side by side, would reach around the world.

Now these molecules, small as they are, are made up of atoms, which are much smaller. You can get an idea how small these atoms are if you remember that if a little bubble of gas the size of an ordinary pin-head were made as large as the world is today, its atoms would then be the size of tennis balls. But these atoms are made up of even smaller things. Atoms are made up of electrons, "particles" of electricity, centering about a "nucleus." If an atom were made the size of St. Paul's Cathedral, each electron in it would be about the size of a small bullet.

By carrying further these statements we can see this story of electrons more clearly. Just as

Now, you will have to stretch your minds a bit to see the next point. What we call "energy" can take many possible forms such as light, heat, electricity, magnetism, and motion. Scientists have discovered that all these forms of energy are interchangeable and that the motion of molecules is just plain heat.

When we come to think about it, we already know that these forms of energy are interchangeable. We know that the motion of a wire around a magnet causes a current of electricity; and that this electricity can be turned back into motion or that it can be turned into heat or that it can be turned into electric light. We know, too, that if a steam or electric hammer were put to work hammering at great speed on a bar of cold iron, the iron would gradually become hotter and hotter and finally would begin to glow. It is indeed true that these forms of energy are all interchangeable.

But now let us go back to electrons. In most substances the electrons are being held together in the incessantly active atom, but it is possible to cause the atom to break up and shoot out electrons. That is what is happening in radium all the time.

And now we come to power. These electrons are shot out of atoms at a speed which may approach 160,000 miles per second. One writer has calculated that it would take 1,340,000 barrels of powder to give a bullet the speed of one of these electrons. He says that the smallest French copper coin contains an energy equal to eighty million horse-power. A few pounds of matter contain more energy than we can extract from millions of tons of coal. Half a brick contains as much energy as we now get from a small

coal field. Every breath we draw contains enough energy in the atoms of the air to drive the wheels of the workshops of the world.

Will science ever tap this enormous energy? Most scientists believe that the day will come when we shall be able to harness and to utilize atomic energy. No one knows when this will happen; it may be a thousand years; it may be done to-morrow; though undoubtedly it will take a long time to develop power machines which can make use of such forces. It took us several generations to develop effective steam-engines. The devices that will be necessary to use atomic energy will, of course, be much more complex and much more difficult to develop.

One thing is certain: if we ever learn to harness atomic energy and to harness it in any effective way, the result will be a new world to live in. We have seen that the harnessing of metals and of steam and gas and electric power has made our world very different from that in which people lived before this harnessing occurred. These devices made it possible for us, by using these natural powers, to multiply our own powers. Now the natural powers that are concealed in the atom are much greater than the natural powers that we have yet harnessed. If this energy is harnessed and used wisely, it will mean enormous things for our living together well.

CLASS ACTIVITIES

1. Pick out the best question on your list and ask one of your classmates to answer it. Does it produce a good answer? If not, why? Will your questions bring out the most important points in the selection? Through discussion agree on the ten best questions. Read the selection a second time so that you may be able to answer each question on the class list.

2. Of what paragraph in Slosson's "Three Stages in Human Progress" does this selection remind you most? Why?

3. What is most needed in order to use the atom as a source of power? Did a similar need appear in the past in the use of other sources of power? Explain with examples.

ADDITIONAL READINGS. — 1. "Billions of Barrels of Oil Locked Up in Rocks," in National Geographic Magazine, 33: 195–205. 2. "Hastening the Downfall of King Coal," in Literary Digest, 78: No. 10, 7-9. 3. “Gambling with Mother Earth," W. G. Shepherd, in Harper's Magazine, 143: 245-252. 4. "The Nation's Undeveloped Resources," F. K. Lane, in National Geographic Magazine, 25: 183-225.

3. THE GLORY OF TOIL

EDNA DEAN PROCTOR

Read this poem slowly, stopping to think with each line of examples of the work mentioned or of preceding selections suggested by the line.

Whether they delve in the buried coal, or plow the upland soil, Or man the seas, or measure the suns, hail to the men who toil! It was stress and strain, in wood and cave, while the primal

ages ran,

That broadened the brow, and built the brain, and made of a brute, a man;

And better the lot of the sunless mine, the fisher's perilous sea, Than the slothful ease of him who sleeps in the shade of his bread-fruit tree;

For sloth is death and stress is life in all God's realms that are, And the joy of the limitless heavens is the whirl of star with star!

Still reigns the ancient order to sow, and reap, and spin;

But oh, the spur of the doing! and oh, the goals to win,

Where each, from the least to the greatest, must bravely bear

his part

Make straight the furrows, or shape the laws, or dare the crowded mart!

And he who lays firm the foundations, though strong right arm may tire,

Is worthy as he who curves the arch and dreams the airy spire; For both have reared the minster that shrines the sacred fire.

Floods drown the fairest valleys; fields droop in the August blaze;

Yet rain and sun are God's angels that give us the harvest days, And toil is the world's salvation, though stern may be its ways: Far from the lair it has led us far from the gloom of the cave Till lo, we are lords of Nature instead of her crouching slave!