LET us begin with an old and trusted definition.“The world is a small, dark object, entirely surrounded by space.”

It is not a“sphere”or a ball but a“spheroid”,which means first cousin to a sphere and consists of a ball slightly flattened at the poles. The so-called“poles”you can find for yourself by sticking a knitting needle through the center of an apple or an orange and holding the object straight in front of you.Where the knitting needle sticks out of the apple or the orange, there the poles are located, one in the middle of a deep sea(the North Pole)and the other on top of a high mountain plateau.

As for the“flatness”of the polar regions, which goes with the definition of a spheroid, it need not disturb you in the least. For the axis of the earth from pole to pole is only 1/300 shorter than the diameter taken at the equator.In other words, if you were the proud possessor of a globe of three feet in diameter(and few globes that you can buy in our stores are as large as that—you would have to go to a museum to find one),the axis would be only 1/8 of an inch shorter than the equatorial diameter, and it would hardly show unless the workmanship had been of exceptional fineness.

Nevertheless the fact is of considerable interest to explorers who are trying to find their way through the polar regions and to those who make a study of the higher forms of geography. But for the purposes of the present book it is sufficient that I have mentioned it.Your physics professor has probably one of those little contraptions in his laboratory that will show you how the poles could not help becoming flat as soon as our speck of dust began to revolve around its own axis.Ask him to let you see it.That will save you a trip to the home of all the meridians.

The earth, as we all know, is a planet. We have inherited the word from the Greeks who had observed(or thought they had observed)that certain stars were forever moving across the skies while others apparently stood still.They therefore called the former“planets”or“wanderers”and the latter“fixed stars”because, having no telescopes, they could not follow them on their peregrinations.As for the word“star”,we do not know its origin but it probably has something to do with a Sanskrit root which was in turn connected with the verb“to strew”.If that be true the stars would then be the little flames“strewn”all over the heavens, a description which is quite pretty and fits the case admirably.

The earth turns around the sun and depends upon the sun for its light and heat. As the sun is more than seven hundred times as large as all the planets put together, and as the temperature of the sun near the surface is about 6000°F, the earth need not feel apologetic about borrowing her humble little portion of comfort from a neighbor who can so easily spare these few charitable rays and will never know the difference.

In the olden days the people believed that the earth was situated in the center of the universe, a small, flat disc of dry land entirely surrounded by the waters of the ocean and suspended in the air like the coffin of Mohammed or a toy balloon that has escaped the hand of a child. A few of the more enlightened Greek astronomers and mathematicians(the first people who dared to think for themselves without asking the permission of their priests)seem to have had a very definite suspicion that this theory must be wrong.After several centuries of very hard and very straight thinking, they came to the conclusion that the earth was not flat, but round, and that it did not hang quietly suspended in the air and in the exact center of the universe, but that it floated through space and was flying at a considerable rate of speed round a much larger object which was called the sun.

At the same time they suggested that those other shining little orbs which seemed to revolve around us against a common background of so-called“fixed stars”were merely our fellow-planets, children of the same mother-sun and subject to the identical laws of behavior which regulated our own daily conduct—such as getting up and going to bed at certain regular hours, and being obliged to follow a track which had been laid out for us at the day of our birth and from which we could not stray without running the risk of instant doom.

During the last two hundred years of the Roman Empire the thinking part of the population had accepted this hypothesis as something so self-evident that it could no longer be considered a subject for debate. But when the Church became all-powerful, shortly after the beginning of the fourth century, it was no longer safe to harbor such ideas, least of all that one which proclaimed the earth to be round.We should not judge them too harshly.In the first place the earliest converts to Christianity generally belonged to those classes of society that had been the least exposed to the current learning of the times.And furthermore they were firmly convinced that the end of the world was near at hand when Christ would return to the former scene of His sufferings to separate the good from the evil.He would return in the midst of all His glory and for every one to behold.But, so they reasoned, and quite correctly from their own point of view, if this were to be the case(and they had no doubt upon the subject)then the world must be flat.For otherwise Christ would have to make His reappearance twice—once for the benefit of the people on the western hemisphere and once for the benefit of those on the other side of the world.Such a procedure, of course, would be absurd and undignified and therefore entirely out of the question.

The church, therefore, for almost a thousand years insisted upon teaching once again that the earth was a flat disc and that it was the center of the universe. In learned circles, among the scientists of a few of the monasteries and among the astronomers of some of the rapidly growing cities, the old Greek conception of a round world, revolving around the sun together with a number of other planets, was never quite discarded.Only the men who held this to be true did not openly dare to talk about the subject, but kept their ideas strictly to themselves.For they knew that a public discussion would merely upset the peace and quiet of millions of their less intelligent fellow-citizens while it would do absolutely nothing to bring the solution of the problem any nearer.

Since then, the Church people too, with very few exceptions, have been forced to accept the notion that the planet on which we live must be a ball. By the end of the fifteenth century the evidence in favor of this ancient Greek theory had become too overwhelming to be refuted any longer.And it was and is based upon the following observations:

In the first place, there was the fact that when we approach a mountain or a ship at sea, we first of all notice the summit or the top of the mast and only very gradually, as we come nearer, are we able to see the rest of the object under observation.

In the second place, no matter where we are, the scene all around us appears to be a circle. Our eyes therefore must be equally removed from every part of the land or sea under observation and the further we get away from the surface of the earth in a balloon or on top of a tower, the larger that circle gets.If the earth happened to be egg-shaped, we would find ourselves in the middle of a large oval.If it were a square or a triangle, the horizon would be a square or a triangle too.

In the third place, when a partial eclipse of the moon takes place, the shadow of the earth on the moon is a circle and only a ball will cause a circular shadow.

In the fourth place, the other planets and stars too are spheres and why should we alone among so many billions be an exception?

In the fifth place, when the ships of Magellan had sailed long enough in a westerly direction, they finally returned to the place from which they had left and when Captain Cook did the same thing, going from west to east, the survivors of his expedition also came back to the port from which they had sailed.

And finally, when we travel northward towards the poles, the familiar constellations of the stars(the signs of the Zodiac of the ancients)disappear lower and lower below the horizon, but they arise again and come higher and higher, the nearer we return to the equator.

I hope that I have brought forward enough undisputable facts to prove that the planet on which we happen to live must be round. But should the evidence be insufficient to satisfy you, go to any reliable professor of physics.He will take one of those stones that are forever falling from high towers and he will let it do tricks with the law of gravity which prove beyond the shadow of a doubt that the earth must be a sphere.If he uses very simple words and does not talk too fast, you may be able to understand him, but only if you know a great deal more about mathematics and physics than I do.

Here I could indulge in a great many very learned statistics, none of which however would be of the slightest use to you. The average mind(the author's mind included)is simply not fit to follow such calculations with any degree of comfort.Take light for example.Light travels at the rate of speed of 186,000 miles per second.It goes seven times around the earth while you snap your fingers once.And yet the light from the nearest of the fixed stars(Alpha Centauri, if you want the correct address)must travel four and one-third years at the rate of 186,000 miles per second ere it strikes our eyes.The sun can reach us in eight minutes and Jupiter in three minutes, but the Polar Star, which plays such an important role in the science of navigation, would need forty years to send us a single ray of light.

Alas, most of us get slightly dizzy when we are asked to“imagine”such a distance, and the very idea of a light-year, or the distance covered by a ray of light in a single year, or 365246060186,000 miles becomes something so enormous that as a rule we say“Oh, yes”,and then go out and play with the cat or turn on the radio.

But all of us are familiar with railroad trains. Let us try it that way:

An ordinary passenger train, going day and night without stops, would need five-sevenths of a year to reach the moon. But if it started today it would not get to the sun until A.D.2232.It would need 8,300 years to get to the suburbs where the planet Neptune lives.All that however would be mere child's play compared to a trip to the nearest of the fixed stars, for that would mean a voyage of 75,000,000 years.As for the Polar Star, that train would need 700,000,000 years to get there and 700,000,000 years is a long time, a very long time.If we put the duration of life for the average human being at about seventy years(which is a very flattering estimate),10,000,000 generations of human beings would have been born and would have died ere that train got to its final destination.

And now we are only talking about the visible part of the universe. Our telescopes are a great deal better than the funny little contraptions with which the contemporaries of Galileo searched the sky and incidentally made some of the most remarkable discoveries.Even so, they are still very imperfect and until we improve our lenses a thousand-fold we shall not make much headway.Therefore, when we talk about the universe, what we really mean is“that small part of the universe which is visible and which has come under our own personal observation or under the observation of those sensitive photographic plates which are substituted nowadays for the human eye”.As for the rest of the universe, the still invisible part, alas, we know nothing about it.And what is worse, we dare not even guess.

Among all these millions of stars, fixed and otherwise, which are our more immediate neighbors, there are only two which influence our own existence in a very direct and noticeable fashion, and those two are the sun and the moon. The sun, because once every twenty-four hours she provides one-half of our planet with heat and light.And the moon, because she is near enough to us to influence the behavior of the ocean and to cause that strange aquatic phenomenon which we know as the“tides”.

The moon is really quite near to us. Therefore, although it is much smaller than the sun(if we represent the sun by our familiar out-sized globe of three feet diameter, the earth would be a green pea and the moon the mere point of a pin),the moon has a much stronger“pull”on the surface of the earth than the sun.

If the earth consisted entirely of solid matter, that pull of the moon would hardly make itself felt. But three-fourths of the surface of the earth consists of water and that water follows the moon on its peregrination across the earth, just as iron filings spread out across a piece of paper will follow the toy magnet you pass across the table.

All day and all night long a broad strip of water, several hundred miles wide, is following in the wake of the moonlight. When it enters bays and harbors and the mouths of rivers and becomes greatly condensed, it causes the tides of twenty or thirty or forty feet difference which make navigation in those waters such a very difficult feat.When the sun and the moon happen to be on the same side of the earth, the pull is of course much stronger than when the moon is there alone, and then we get a so-called“spring-tide”;and a spring-tide in many parts of the world is something very much akin to a small inundation.

The earth is entirely surrounded by a layer of nitrogen and oxygen which we call the atmosphere or the“air”. This layer is supposed to be about 300 miles thick and it turns around together with the earth just as the skin of an orange turns around with the inside of the orange which it protects.

Only a year or so ago a Swiss professor in a specially designed balloon went ten miles up in the air, into that part of the atmosphere which had never been visited before. That was quite a feat, but 290 miles still remain to be explored.

The atmosphere, together with the surface of the earth and the sea, is the laboratory in which all our different sorts of weather, our winds and our rainstorms and blizzards and our dry periods, are manufactured. As these influence our happiness and well-being every hour of our lives, we ought to discuss them here in considerable detail.

The three factors which make our climate what it is are the temperature of the soil, the prevailing wind and the amount of moisture which is present in the air. Originally“climate”meant the“slope of the earth”.For the Greeks had noticed that as the surface of the earth“sloped”further and further towards the poles, both the temperature and the humidity of the spots they visited also changed, and in that way“climate”came to mean the atmospheric condition of any given region rather than its exact geographic position.

Today when we speak of the“climate”of a country, we mean the average weather conditions which prevail there during the different parts of the year and it is in that sense that I shall use the word.

First of all let me say something about those mysterious winds which have played such a great role in the civilization of mankind. For without the regular“trade-winds”of the equatorial ocean, the discovery of America might have been deferred until the age of the steamboat.Without the dew-laden breezes.California and the countries of the Mediterranean would never have reached that degree of prosperity which sets them apart from their neighbors in the north and in the east.Not to mention the particles of rock and sand which, swept forward by the wind, will act as gigantic, invisible sheets of sand-paper, and which after millions of years will grind even the most powerful mountain ranges from the face of the earth.

This word“wind”means literally something that“winds its way”. A wind, therefore, is a current of air“winding its way”from one place to another.But why does a current of air wind its way from one place to another?Because some of the air is usually warmer than the rest and therefore lighter and has a tendency to rise as high as it can go.When that happens, there is a vacuum.The cold air, being heavier, rushes into that vacuum, because, as the Greeks had already discovered two thousand years ago,“Nature abhors a vacuum”,and air is just as much of a vacuum-hater as water or the human race.

We know of course how we can produce hot air in any given room—by the simple expedient of lighting a fire. Among the planets the sun is the stove and the planets are the rooms which are to be heated.The greatest amount of heat will of course be nearest to the stove(along the equator)and the smallest amount of heat will be found furthest removed from the stove(near the North and South Poles).

Now a stove causes a considerable commotion in the air—a circular commotion. The hot air will rise towards the ceiling.As soon as it gets there, it will be further removed from the original source of heat than it was before, and as a result it will begin to cool off.The cooling process will cause it to lose its lightness and to fall back towards the earth.But as soon as it gets a little lower, it will once more get in touch with the stove.Once more it will grow warmer and lighter and once more it will begin to rise.And so on and so forth, until the stove goes out.But then the walls of the room, which have absorbed considerable heat while the stove was burning, will keep the room warm for a shorter or longer time, depending upon the material of which they are made.

These walls may be compared to the soil on which we happen to five. Sand and rocks absorb heat quicker than a rain-soaked marsh, but by the same token they let go of it with much greater ease.As a result, the desert is uncomfortably cold a short time after the setting of the sun, while a forest remains warm and comfortable for hours after the entrance of darkness.

Water is a veritable reservoir for the storing up of heat. As a result all countries situated on or near the ocean enjoy a much more even temperature than those located in the heart of a continent.

Since our stove, the sun, burns much longer and more fiercely in summer than in winter, it follows that the summer must be warmer than the winter. But there is something else that influences the action of the sun.If you have ever tried to make the bathroom a little less shivery on an extra cold day with a small electric heater, you will know that much depends upon the angle at which that little stove is placed.The same holds true for the sun.In the tropics, the rays of the sun hit the surface of the earth much more directly than near the poles.A ray of sunlight, therefore, a hundred miles wide, landing fairly and squarely upon a hundred miles of African forest or South American wilderness, will be able to devote its entire strength to these hundred miles of territory and to nothing else.But near the poles, a ray of sunlight a hundred miles wide will cover a stretch of land or ice that is twice as wide(as the picture will show you much more easily than a thousand words could hope to do),and the heating power of those hundred miles of sunlight near the poles will therefore be cut exactly in half, just as an oil-burner which is suppósed to keep a six-room apartment at a comfortable temperature will prove a failure when called upon to perform a similar service for a twelve-room flat.

What makes the job of our celestial stove even more complicated is the fact that the sun must also keep the atmosphere which surrounds us at an even temperature. But she cannot do this directly.She must do it indirectly, via the earth.

On their way to our planet the sun rays pass through the atmosphere, but they pass through so easily and quickly that they hardly influence the temperature of that faithful terrestrial blanket. Then they hit the earth and the earth stores up the heat and slowly surrenders part of it into the atmosphere.That fact, incidentally, explains why it is so cold on the top of a mountain.For the higher we get, the less the heat of the earth has been able to make itself felt.If(as used to be supposed)the sun heated the atmosphere directly and the atmosphere in its turn heated the earth, it would be just the other way around and our mountain tops would not be covered with snow.

And now we come to the most difficult part of the problem. Air is not just“air”in our sense of the word.It has both substance and weight.The lower layers of air therefore are under a much higher pressure than the higher ones.When you want to flatten out a leaf or a flower you put it between the pages of a book and then put twenty other volumes on top of it because you know that the pressure will be greatest in the book that is at the bottom of the pile.The pressure under which we human beings live is considerably more than most of us suspect.It is fifteen pounds per square inch.That means that we would be crushed flat except for the fortunate circumstance that we are filled with the same air as that which surrounds us.Even so,30,000 pounds(the pressure upon a body of average size)is a respectable amount.If you have any doubts upon the subject, try to lift a small freight-car.

Within the realm however of the atmosphere itself that pressure is constantly changing. We know this through the invention of Evangelista Torricelli, a pupil of Galileo, who early during the seventeenth century gave us the barometer, that well-known instrument by which we are able to measure the pressure of the air at any time of day or night.

As soon as the first of these Torricellian tubes had been placed upon the market, people began to experiment with them. They noticed that the pressure fell by about an inch for every 900 feet one ascended above sea-level.Then followed another discovery which did so much to make meteorology, the study of atmospheric phenomena, such a reliable science in forecasting the weather.

Certain physicists and geographers began to suspect that there was a definite connection between the pressure of the air and the direction of the prevailing winds or vice versa. But in order to establish some irrefutable law regulating the behavior of all air-currents, it was first of all necessary to spend several centuries collecting the data from which to draw a few definite conclusions.When this had been done, it was shown that certain parts of the world enjoyed an air pressure well above that of the mean sea-level, while others had pressures far below the mean sea-level.The first of these were then called high-pressure areas and the second low-pressure areas.Next it was definitely established that winds would always tend to blow from high-pressure areas to low-pressure areas and that the velocity and strength of the wind would depend upon the highness of the high-pressure area and the lowness of the low-pressure area.And when the high-pressure was very high and the low-pressure was very low, then we would have a very violent wind—a storm, a cyclone or a hurricane.

The winds not only keep our living quarters, the earth, decently ventilated, but they also play a great role in the distribution of that rain without which a normal development of plant life and animal life would be completely impossible.

Rain is merely evaporated water from the oceans and from the inland seas and from the inland snow-fields, which is carried along by the air in the form of vapor. As hot air can hold much more vapor than cold air, the water-vapor will be carried along without much difficulty until the air grows colder.Then part of it gets condensed and falls back again upon the surface of the earth in the form of rain or hail or snow.

The rainfall of any given region therefore will depend almost entirely upon the winds to which it is exposed. If we have a sea-coast separated from the mainland by mountains(a very common occurrence)the coastal region will be wet and damp.For the wind, being forced to rise into higher regions(where the pressure is lower),will cool off as it gets further and further away from the sea-level and it will shed its vapor in the form of rain and snow and will reappear on the other side of the mountain range as a dry wind without a drop of moisture.

The rainfall of the tropics is both regular and abundant because the enormous heat of the land makes the air rise to a great height, where it gets cooled off and is obliged to let go of most of its vapor, which thereupon returns to earth in the form of heavy sheets of rain. But as the sun does not always stand right over the equator, but moves slightly from north to south, most of the equatorial regions enjoy four seasons, two seasons during which there are terrific rainstorms and two seasons during which the weather is dry.

But those regions which are exposed to steady air-currents running from colder to warmer regions are by far the worst off. For as the winds pass from the cold area to the hot one, their capacity for absorption becomes steadily greater and they are unable to release the vapor they carry, causing many parts of this earth to be turned into deserts where it may not rain more than once or twice every ten years.

So much for the general subject of wind and rain. A detailed discussion will follow when we describe each individual country.

And now a few words about the earth itself, and about that thin crust of hardened rock on which we live.

There are a great many theories about the true inner nature of our planet, but our definite knowledge upon the subject is still exceedingly vague.

Let us be honest. How high have we ever been up in the air or how low down into the bowels of the earth?

On a globe of three feet in diameter, the highest mountain in the world, Mt. Everest, would show about as thick as a thin piece of tissue paper and the deepest hole in the ocean, just east of the Philippine Islands, would be represented by a dent of the size and shape of a postage stamp.Well, we have never yet descended to the bottom of the ocean and we have never yet climbed Mt.Everest.We have been a little higher than the top of this Himalayan giant in balloons and flying machines, but when all is said and done, even after the recent successful flight of the Swiss Professor Piccard,29/30 of the atmosphere still remain to be explored.As for the water, we have never yet descended below 1/40 of the total depth of the Pacific Ocean, and incidentally, the depth of the deepest sea is greater than the height of the highest mountain.Why this should be we do not know, but if we dumped the highest mountains of the different continents into the deepest part of the ocean, the tops of Mt.Everest and Aconcagua would still be several thousand feet below the surface of the sea.

In the light of our present-day knowledge however these puzzling facts prove nothing at all about the origin and the subsequent development of the crust of the earth. Neither(as our grandfathers so fondly hoped)need we turn to our volcanoes for an answer about the true inner nature of our planet, for we have come to realize that those are not outlets for the hot substance that is supposed to fill the interior of the earth.If the comparison were not quite so unsavory, I would like to compare them to boils on the skin of the earth, nasty afflictions but purely local affairs which never penetrate very deep into the body of the patient.

In round numbers there are still some 320 active volcanoes left. There used to be 400 others on the active list, but these have since been retired and pensioned off with the rank of ordinary or common mountains.

The great majority of all these volcanoes are situated near the sea-coast. Indeed, the most restless part of the world's crust, Japan(where the seismograph shows a slight volcanic disturbance four times every day or 1,447 times a year)is an island, and so were Martinique and Krakatoa, the most tragic victims of recent volcanic outbursts.

In view of the close proximity of sea to volcano, it was quite natural that people should have tried to explain all volcanic eruptions as the result of water seeping into the inner part of the earth, thereby causing a sort of gigantic boiler explosion with the well-known disastrous results of an overflow of lava and steam and what have you. But since then we have discovered several very busy volcanoes hundreds of miles away from the sea, and that theory too has therefore come to naught.Ask me again about all this two centuries hence for at the present moment we can only shake our heads and repeat,“We do not know.”

Meanwhile, what about the surface of the earth itself?We used to talk so glibly about the rock of ages that would forever defy the changes of time. Modern science is less confident and regards this rock and all other rocks as something living and therefore subject to constant change.The rain raineth upon it and the wind bloweth upon it and together they cause the mountains to wither away at the rate of three inches every ten centuries.If there were no counter-moves to offset these erosive attacks, all our mountains would have disappeared long ago and even the Himalayas would have been turned into a vast plain in about 116,000,000 years.But there are counter-activities and plenty of them.

In order to get at least a vague idea of what is really happening all around us, take half a dozen clean handkerchiefs and spread them out flat on the table, one on top of the other. Then push all six together by moving your hands very slowly towards each other.You will get a pile of curiously wrinkled linen with mountains and valleys and folds and counter-folds all over it and that pile of curiously wrinkled linen will bear a very close resemblance to the crust of the earth.That crust is part of an enormous structure racing through space and constantly losing some of its heat.Like all things that are cooling off, it is slowly contracting.As you probably know, when an object contracts, the outer surface will get curiously rumpled and creased like a couple of handkerchiefs being pushed together.

The best guess at the present moment(but remember that it is only a guess)tells us that the diameter of the earth has shrunk some thirty miles since the beginning of our independent existence as a planet. That does not seem very much when you think of it as a straight line.But remember the tremendous scope of the curved planes with which we are dealing.The surface of the world is 196,950,000 square miles.A sudden change of only a few yards in diameter would be enough to cause a catastrophe which none of us would survive.

Nature therefore works very slowly her wonders to perform. She insists upon maintaining a proper balance in everything she does.When she allows one sea to run dry(our own Salt Lake is rapidly dwindling away, the Lake of Constance in Switzerland will be gone in another 100,000 years)she starts another one in some other part of the world;and when she permits certain mountain-ranges to disappear(the Alps in central Europe will be as flat as our prairies in another 60,000,000 years)then another part of the crust in a totally different corner of the globe is slowly being reshaped and wrinkled into a fresh mountain-range.That, at least, we believe to be the case, although as a rule the process is by far too slow and gradual to allow us to make any concrete observations of the changes that are taking place.

There is however an exception to this general rule. When left to herself, Nature is in no particular hurry.But when aided and abetted by man, she sometimes proves herself an uncomfortably fast worker.And ever since man became truly civilized and invented his little steam-engines and his little sticks of dynamite, the surface of the earth has been transformed so rapidly that our great-grandparents would hardly recognize their own pastures and gardens, were they to come back to us for a little holiday.Our greed for timber and the ruthlessness with which we have denuded whole mountain-ranges of their blanket of forests and shrubs have turned vast regions into primeval wildernesses.For as soon as the forests were gone, that fertile soil which for so many years had faithfully clung to the rocky surface of the hill-sides was brutally washed away and the barren slopes became a menace to the surrounding country-side.The rain was then no longer held captive by the turf and by the roots of the trees, but was able to rush down towards the plains in torrents and cataracts, destroying everything it met on its way towards the valleys and plains.

And this unfortunately is not said in a flight of high rhetorical exaggeration. We don't have to go back to the glacial periods when, for reasons as yet unexplained, the whole of northern Europe and northern America lay buried beneath a heavy blanket of ice and snow which dug such dangerous grooves through entire mountain-ranges.We need only go as far back as the era of the Romans, who were first-rate exploiters(weren't they the“practical men”of antiquity?)and who in less than five generations completely changed the climate of their own peninsula by the senseless destruction of everything that had thus far helped to make Italy a country of well-balanced and even temperature.And what the Spaniards did to the mountains of South America, when they allowed the fertile terraces, built by countless generations of patient little Indians, to go to ruin, is a fact of such recent occurrence as to need no further elucidation.

Of course that was the easiest way to deprive the natives of their livelihood and reduce them to obedience by way of starvation—just as the extinction of the buffaloes by our own government was the most practical method of turning fierce warriors into dirty, slovenly reservation-parishioners. But these cruel and senseless measures carried their own punishment with them, as any one familiar with our plains or the Andes will tell you.

Fortunately this is one of the few problems of practical geographical importance which has at last penetrated to the consciousness of those who sit in the seats of the mighty. No government today would any longer tolerate such scandalous interference with the soil upon which all of us depend for our well-being.We have no control over the cosmic changes which take place in the crust of our planet.But to a certain extent we can control a vast number of details which make for a greater or smaller rainfall in any given territory and which will prevent fertile regions from being turned into howling deserts.We may not know anything about the inside of this earth, but we have at least learned a great many things about the outside.And every day we add to the total sum of this useful bit of information and use it wisely for the benefit of all.

But I regret to say that we have no such control over the greater part of the earth's surface—that part which we call the oceans and the seas. Almost three-quarters of our globe are uninhabitable because they are covered by a layer of water, differing in depth from a couple of feet(near the shore)to almost 35,000 feet in the famous“deep hole”just east of the Philippines.

This layer of water can be roughly divided into three main parts. The most important of these is the Pacific Ocean which covers 68,500,000 square miles.The Atlantic Ocean covers 41,000,000 square miles and the Indian Ocean 29,000,000.Inland seas account for another 2,000,000 square miles, while lakes and rivers take up about 1,000,000 square miles of their own.All this submerged territory was and is and always will remain lost to us as a place of residence, unless we are able to redevelop those gills which our ancestors of a few million years ago possessed and of which we still show the traces on the day of our birth.

This abundant supply of water may at first seem a complete waste of perfectly good territory and it may make us regret that our planet is as wet as it happens to be. For when we remember that 5,000,000 square miles of the land that is at our disposal are desert and that 19,000,000 square miles are steppes or plains of the semi-useless Siberian variety, while a considerable number of other millions of square miles are uninhabitable because they are either too high for us to live in(like the Himalayas and the Alps)or too cold(like the territory around the North and South Poles)or too wet(like the swamps of South America)or too densely covered with forests(like the forests of central Africa)and must therefore be deducted from the 57,510,000 square miles that are listed as“land”,we feel that we could make excellent use of a few more miles of added territory.

But it is extremely doubtful whether we could exist at all if it were not for this vast reservoir of heat, which we call the sea. The geological remnants of prehistoric times show us conclusively that there have been times when there was more land and less water than today, but invariably these were periods of intense cold.The present balance of 4:1 between water and land is an ideal one if our present climate is to continue indefinitely, and we shall all of us be much better off if it does not get disturbed.

This vast ocean which encircles the entire globe(in this respect the ancients had guessed right)is, like the solid crust of the earth, in constant motion. The moon and the sun, through their power of gravity, attract it and cause it to rise to a considerable height.Then there is the heat of the day which takes part of it away in the form of vapor.The cold of the polar regions covers it with ice.But from a practical point of view as something directly affecting our own well-being, the air-currents or winds must be accorded first rank for their influence upon the surface of the ocean.

When you blow long enough on your plate of soup, you will notice that the soup begins to move in the direction away from your mouth. When certain air-currents hit the surface of the ocean for years and years in succession, they will cause“drifts,”which will move in a direction away from that particular current.Whenever there are a number of air-currents blowing from different directions, these different“drifts”will neutralize each other.But when the winds are steady, as they are for example on both sides of the equator, the drifts become veritable currents and these currents have played a very important role in the history of the human race and in making certain parts of the world inhabitable which otherwise would be as cold as Greenland's icy shores.

A map of these ocean rivers(for that is what many of those currents really are)will show you where they are located. The Pacific Ocean has a number of such currents.The most important of these, as important in its way as the Gulf Stream of the Atlantic, is the Japan current or Kuro Siwo(which means the Blue Salt Current)which is caused by the north-east trade-winds.After having done its duty by Japan, it crosses the northern Pacific and bestows its blessings upon Alaska, which it keeps from being too cold for human habitation, and then, turning sharply towards the south, gives California its agreeable climate.

But when we speak of ocean currents, we think first of all of the Gulf Stream, that mysterious river, some fifty miles wide and 2000 feet deep, which for untold centuries has kept the northern part of Europe well supplied with the tropical heat of the Gulf of Mexico and which accounts for the fertility of England, Ireland and all the North Sea countries.

The Gulf Stream has an interesting career of its own. It begins with the famous North Atlantic Eddy, a drift rather than a current, which like a gigantic maelstrom turns around and around in the central part of the Atlantic and enfolds within itself that pool of semi-stagnant water which has become the home of billions of little fishes and floating plants and which, as the Sargasso or“Sea-Weed Sea”,played a most important part in the history of early navigation.For once the trade-winds(the eastern winds that blew just north of the tropics)had blown your ship into the Sargasso Sea, you were lost.At least, that is what the sailors of the Middle Ages firmly believed.Your vessel would find itself caught by miles and miles of solid sea-weed and every one on board would slowly perish through hunger and thirst, while the ghastly wreck would remain forever bobbing up and down beneath the cloudless sky as a silent warning to others who might be tempted to defy the Gods.

When finally Columbus sailed placidly through the heart of this dullish stretch of water, it was shown that the fairy story about miles and miles of solid sea-weed had been grossly exaggerated. But even today there is something mysterious and uncanny to most people in that name, Sargasso Sea.It sounds medieval.It smacks of one of Dante's infernal circles.Actually, however, it is no more exciting than the swan-pond in Central Park.

But to return to the Gulf Stream. Part of the North Atlantic Eddy finally finds its way into the Caribbean Sea.There it is joined by a current that moves westward from the coast of Africa.These two currents, in addition to its own water, are too much for the Caribbean Sea.Like a cup that has been poured too full, it flows over into the Gulf of Mexico.

The Gulf of Mexico has not got room for all this additional humidity and, using the straits between Florida and Cuba as a spigot, it pours forth a broad stream of hot water(80°F)which thereupon is called the Gulf Stream. When the Gulf Stream leaves the spigot, it flows at the rate of five miles an hour, which is one of the reasons why the old sailing vessels gave it a wide berth whenever they could and preferred to make a lengthy detour rather than try to navigate against a current which so severely delayed their own progress.

From the Gulf of Mexico the Gulf Stream moves up northward, following the American coast until finally it is deflected by the shape of the eastern shore, when it begins its voyage across the north Atlantic. Just off the Grand Banks of Newfoundland it meets its own offspring, the so-called Labrador Current, which, coming fresh from the glacial regions of Greenland, is as cold and uninviting as the Gulf stream is warm and hospitable.Out of the meeting of these two mighty currents arises that terrible fog which has given that part of the Atlantic such a dreadful reputation.It also accounts for the presence of that large number of icebergs which have played such a hideous role in the nautical history of the last fifty years.For, cut off by the summer's sun from their solid Greenland moorings(those glaciers that still cover ninety percent of that vast island)these bergs drift slowly southward until they are caught by the eddy caused by the meeting of the Gulf Stream and the Labrador Current.

There they mill around while they slowly melt. But this melting process is what makes them so dangerous, for only the tops remain visible while the ragged edges stay under water, just deep enough to cut through the hull of a ship as a knife cuts through butter.That whole region today is forbidden territory for all ocean liners and it is constantly watched by United States patrol vessels(a special ice patrol, paid for by all nations)who blow up the smaller bergs and warn vessels of the presence of the bigger ones.Fishing boats, however, love this territory, for fishes who were born in the Arctic and were therefore accustomed to the cold temperature of the Labrador Current feel very unhappy in the tepid water of the Gulf Stream.While they are slowly making up their minds whether to go back to the Pole or try to swim across the warm Gulf Stream, they are caught by the nets of those French fishermen whose ancestors patronized the legendary Grand Banks of America hundreds of years before any one else.The two little islands of St.Pierre and Miquelon, off the Canadian coast, are not only the last remaining remnants of that vast French empire which two centuries ago covered the greater part of the North American continent.They also bear silent witness to the courage of the Nor many fishermen who had visited our shores at least a hundred and fifty years before Columbus was born.

As for the Gulf Stream, after leaving the so-called Cold Wall(produced by the difference in temperature between the Gulf Stream and the Labrador Current)well to the north, it then leisurely moves across the Atlantic Ocean and spreads fan-wise over the coast of western Europe. It touches Spain and Portugal and France and England and Ireland and Holland and Belgium and Denmark and the Scandinavian peninsula, and bestows upon all these countries a much milder temperature than they would otherwise enjoy.Having thus done its duty by humanity this strange current, carrying more water than all the rivers of the world combined, withdraws discreetly into the Arctic Sea.This sea thereupon finds itself so full of aquatic substance that it must find relief by sending out a current of its own, that Greenland Current which in turn is responsible for that Labrador Current I have just described.

It is a fascinating story.

It is such a fascinating story that I am sorely tempted to give by far too much space to this chapter alone. But that I must not do.

This chapter can only be a background—a general background of meteorology and oceanography and astronomy against which the actors in our play shall shortly act their part.

Now let us drop the curtain for a second.

When it rises, the stage is set for a new act.

That act will show you how men learned to find their way across those mountains and seas and deserts that had to be conquered ere we could truly call this world our home.

The curtain rises again.

Act　Ⅱ:Maps and methods of navigation.