IN THE walls of the canyons and cliffs of New Mexico and Arizona there are to be seen the ruins of prehistoric dwellings, built by a race which lived so long ago that no other record of them remains. The cliff dwellers who built their homes in the hollows and ledges and recesses of these narrow high-walled canyons, back in the days before written history, were probably ancestors of the Pueblo Indans who still dwell in these regions. Their homes were tucked away in the walls, with only a hole and a few slabs of red sandstone to mark them, because they were safer there from attack than in the more open valleys. Those were the very earliest days, before men had any knowledge of tools for building, before they mixed lime into mortar, before they made adobe bricks. They were the days, too, before men kept any count of time.

Yet do you not think that even the cliff man, knowing the daily change from darkness to light, looked up at the sun in awe and worship and watched it take its daily course across the heavens? Do you not think that the cliff woman measured the length of the day, when her men-folk were off hunting, by the shadows on the cliff walls? When the men set off for the hunt, it was early dawn. As the sun climbed higher in the eastern sky, the dark shadow on the western wall of the cliff began to move downward before the sun’s rays. All the morning the shadow crept down the cliff side until at noon the sun stood directly above the narrow canyon, into which poured as much light as ever came within those towering walls. Then perhaps the man came home, bringing the body of some little animal which he had tracked and killed for food, and before the shadow crept to the top of the other side of the cliff and darkness fell there would be a rude meal eaten on the ledge in front of the hollow where they slept. The sun is the world’s greatest timepiece. The walls of the cliff were the face of the cliff dweller’s clock, while the moving shadow was the hand that told time.

The cliff dweller had the walls of the cliff on which to mark the progress of the shadows. The herdsman or the tent dweller on the plains must measure time by the shadow cast by a tree or stone. Some day, which was a wonderful day in the history of any tribe where it happened, a man who was more clever and more systematic than his fellows, set up a pole where there was no tree or rock and put a stone to mark for all succeeding days the point where the shadow fell when the sun was highest in the heavens. That was the first time that a man went beyond the provision which Nature had made for him and deliberately of his own choice set out to divide his days by a regular measure. And if a stone for the shadow at noonday, why not one for early morning, and one for midafternoon? In a circle of stones with a stick to throw a shadow, the clock face with its marking of the hours was born. The sundial was the forerunner by many hundreds of years of the clock.

Time, except in big sections like morning, noon, and afternoon, mattered as little to the savage man living with his family in a cave as it would to a Robinson Crusoe cast up on a desert island. But when men began to come together in villages and towns and to plan their lives together, it was convenient to have a system with shorter periods. So the face of the sundial was marked with lines at regular spaces to indicate regular intervals of time.

The very earliest records of time telling come from a wonderful people, the Babylonians, who lived in the rich region east of the Mediterranean Sea between the Tigris and Euphrates rivers. Mesopotamia, "The Land Between the Rivers," is the name by which we know the rich, fertile country in which they dwelt. They built houses and walled cities of sun-dried bricks, and their wise men ("magi") became learned in the "magic" of the sun and moon and stars. The sun was their god Shamash, and the moon and the planets were also gods. Shamash was the god of order, too, for his priests studying his movements and those of the other heavenly bodies saw that they proceeded in regular courses. The savage man had probably noted that the shape of the moon changed from a thin crescent to a circle and back again, and had perhaps come to count time from full moon to full moon. But the Chaldean and Babylonian priests made careful mathematical studies of all these matters. They saw that the sun changed the points at which it rose and set, traveling toward the north at one time of the year and toward the south at another. They kept a record of the length of the sun’s days as it made this yearly journey.

Finally this school of priests made a chart in which they laid out on paper, as if they were drawing a map, the facts which they had learned in their sun gazing and star gazing. This chart, which is called the "zodiac," was round like a wheel, or like the sky as they thought of it, for they believed the earth was flat and the sky was like a great bowl turned upside down over their heads. In the center of the wheel they put the sun. A little farther out was the moon, moving around the sun in its four positions, new moon, half moon, full moon, and half moon again. Around the edge was a belt divided into twelve Sections. These were the signs or "houses" of the zodiac. In them dwelt the fixed stars or groups of stars, each house being named for its leading star or group.

Here we see for the first time the use of the figure twelve, on which our whole system of time keeping is built. The Babylonians figured out a year as having twelve moons or months. They divided day and night into twelve hours each, making a day of twenty-four hours. Then they divided the hour into sixty minutes, and finally the minute into sixty seconds. They were wise old mathematicians, these Babylonian and Chaldean priests who lived four thousand, three thousand, two thousand years before the coming of Christ. It was not by chance that they hit on these figures of twelve and twenty-four and sixty. No number smaller than sixty can be divided into so many other numbers as sixty. If you look at your clock or watch, you can see how simple it is to divide its face into five-minute periods, and also into quarter-hours and half-hours. We owe a great deal to these ancient "magi," who gave us our time scheme in twelves.

These priests kept much of their learning to themselves, for they liked to be regarded as a very learned body, skilled in deep, dark mysteries, to whom the common people came to have their fortunes told and their lives predicted according to the lore of the stars. But part of it did get to the common people for their convenience in time telling. The sundials were marked on the twelve-hour scheme. But the very thing that the priests had noticed as to the movements of the sun made trouble here. The yearly motion of the sun, as it went north and then south, made the swing of the shadow change from day to day. So the sundials were sometimes behind and sometimes ahead in their shadow pointing.

Berosus, a Babylonian priest of Baal, living about the year 250 B.C., came to the rescue here and hit on a clever way to get around this trouble, caused by the north and south movements of the sun. He made his dial hollow like the inside of a bowl so that it would reflect accurately the movement of the sun in the great upside-down bowl of the sky. His pointer was put above this with a little round ball on the end, and the time was marked by the shadow of this ball. A vertical pointer, standing upright like a tree, would not have worked; but with this horizontal pointer reaching out over the bowl, he was able to get the result he wanted. However the sun moved, the shadow moved in the bowl just as the sun appeared to move in the arching sky. By an ingenious set of lines of longitude drawn across the bowl, he got a dial or "hemicycle" (half circle) which kept time fairly accurately all the year round. The hemicycles of Berosus were used all through the ancient world. Cicero had such a hemicycle nearly two hundred years later. Hemicycles of Berosus were found in the ruins of Pompeii. The old Chaldean had made an instrument by which his knowledge became of use to the people of his own and later generations in the practical business of time telling.

Sundials of one kind and another were the most common timepieces all through the Middle Ages, and have lasted to our own day. "Gnomons" they were sometimes called, from the Latin name for the pointer giving the shadow, which was counted almost as a person, "the one who knows." But the trouble with the "gnomon" was that it did not always know. "I count but sunny hours," reads the inscription on an ancient dial. On rainy days or in dull seasons, and at night, the sundial was of no more use than any other piece of metal. The "gnomon" was the servant of its master the sun. When the sun disappeared, how was a man to time his life and keep his appointments? The gnomon could not answer, but the "water-thief" could.

The first part of this story, which goes back of recorded history, might be told in Babylon or ancient Egypt as well as in India or China. Suppose we have it as a Chinese scholar of the old school might tell it.

"There was once a learned judge who was never idle. All day he sat in judgment in the market place of his village, hearing and settling wisely the complaints and quarrels of the people. When evening came he occupied himself in his home with the things for which he cared, with music and the study of the ancient books, and visiting with his family and friends. But the people followed him even to his house and waited in the courtyard until he came out to them. He could hardly finish his evening meal before he was summoned by his neighbors and visitors.

"‘How can I have any life of my own?’ he said to himself. ‘It is not good for a man to eat in haste and never rest or meditate on the words of the ancient sages. I must tell the people when I can see them and when I cannot.’

"In the daytime the people kept time by the place where the sun stood in the heavens or by the length of their own shadows. The judge could say to them, ‘Come to me when the sun stands directly above your heads,’ or ‘Come when your shadow is as long as you are.’ But in the evenings or on rainy days there seemed to be no way to tell them.

"One evening when he had been away all day and returned home very late, he found a company of farmers waiting to settle a dispute over some land. The judge must have his evening meal and rest before he could see them and hear their long stories.

"There stood in the corner of the courtyard a little Chinese garden of green things growing, and on a shelf above it a clever servant had placed a jar with a little hole in the bottom, so that the water from it would come slowly on the plants instead of being poured on them all at once. There was a little trough to carry the water from the hole, so that it was as if a tiny brook were running through this garden.

"As the judge stood welcoming the farmers, a servant came out to fill the jar. Seeing him do it, the judge said to the men, ‘See, I will come out to you when two jars have run out,’ for he knew that the servant kept watch when he was watering the garden and filled the jar as fast as it became empty. The men, who had been disappointed when the judge would not see them at once, sat down in the courtyard, ready to watch and wait patiently as the water ran in a tiny trickle from the jar. Meanwhile the judge ordered his servant to tell him when he went to fill the jar for the third time.

"When the men had gone and the judge sat at rest in the courtyard, he looked at the water jar and said to himself: ‘Why not have more jars to keep time for me? They would mark the time on rainy days and at night.’

"So the judge set up both at home and in the courtyard by the market place water jars with holes in them, which kept time for him and for those who came to him. And before long other people began to keep time by water jars, so that they became known all over China, and may be seen even to this day in some of the ancient cities of the old Chinese Empire."

So the story might be told in China. Jars with dripping water were used there as time measures in 3000 B.C. and possibly as far back as 4000 B.C.

In India a copper bowl with a small hole in the bottom was floated on water in a larger vessel. When the water had pushed up through the hole so that the bowl was partly filled, the bowl would sink to the bottom of the vessel. A watching slave would lift the bowl, empty it, strike on it with a clapper or stick, thus marking for the household that an hour or half-hour or whatever the period of time might be had passed, and then float it again on the surface of the water.

The Babylonians and the Egyptians used water clocks. Finding that water ran out faster when a jar was full, owing to the weight of the water, they put two jars together. The upper vessel had water always flowing into it through a pipe. It had also an overflow pipe by which water ran out if it reached more than a certain height. In this way the weight of water in this vessel could be kept fairly uniform. With the weight of water the same, it would drip from a hole in the bottom at a regular rate into a second and larger vessel placed below. In this second vessel there was a float with a pointer. This float would rise regularly and so could be used as a time guide, as we use the hand of a clock.

The interesting thing about these water clocks, even the simplest of them, is that they actually measured time. The sundial was a device for reckoning time by the sun. The sun really gave the time for the dial. At a time which we nowadays name ten o’clock in the morning the shadow on the sundial would always stand at a certain mark, which became the mark for ten o’clock. The water clock measured the hours as a modern clock does, by the length of time covered. It kept time by having a regular interval between the moment of its being filled and the moment of its becoming empty. It could be timed by the sun, so that one might know how many hours it took for the water to run out. But in its plan it was simply a time measure. Fill it at ten o’clock and it would run for six hours and so tell you when the hour of four o’clock arrived. Fill it at twelve and it would tell you by the dripping of its last drops when six o’clock came. If the vessel of water was very large and the hole very small, it might take the twenty-four hours for the water to run out. It was new and different from the sundial in that it worked by the law of dripping water, independently of any other body. In this it was like a machine.

At first it was not a self-running machine. Someone had to pour in the water. Then came the clepsydra, or as the two Greek words which make up that name are translated, the "water-thief," and that was a self-running time-keeping machine, the first in the world’s history.

They say Ctesibus of Alexandria was the first to put wheels into the water clock. In so doing he added another chapter to the "romance of the wheel" and also made the clock run itself. Here was a float with a pointer the rise of which was controlled by water. Ctesibus fastened a cord to the float, ran the cord over a pulley and let the cord turn a wheel. The rising of the water supplied the motive power to keep it going, just as the flowing of water keeps water wheels turning in a stream. If a wheel was kept turning regularly by the rise of the water, a pointer on that wheel could be made to show the time on a clock face, much as the shadow marked it on the face of the dial. The old "water-thief" really looked a little like our modern clocks. Like them it marked the time, clicking it off by the turns of its wheel so that to those who stood and watched it turn, it seemed to be actually stealing away the time. Sometimes a tiny figure of a man with upraised arm was set as the pointer, that he might be a warning to all who saw him moving around the circle of the clock face. As he moved time was passing, slipping away into eternity.

The Clepsydra or "Water-Thief" The first self-running time-keeping machine in the world's history.

Clepsydras were used throughout the Roman world. They were expensive. If they were to keep time accurately their machinery had to be made very carefully and constantly kept in order. But for public buildings and squares and for rich private homes they were most useful. Pompey the Great, the Roman general who lived from 106 to 48 B.C., had these clocks put in the courts where the lawyers were given to endless speech making, "to stop their babblings." He may have taken the idea from the Athenian courts of justice where the "water-thief" was also used to limit the length of pleas. "The first water," says an ancient writer, Æschines, "was given to the accuser, the second to the accused, and the third to the judges." A special court official was charged with the duty of watching the clock and giving notice to the speakers.

The water clock had certain faults due to the very fact that it was run by water. In the north of Europe it was likely to freeze in winter. Then, water wearing on the hole made the hole larger and let the water run through too quickly. The hole was finally plated with gold, which lasted fairly long. Again, if the water was not perfectly pure, dirt gathered around the hole and made the stream run more slowly.

Father Time did away with these difficulties in his hourglass, where sand ran from one funnel-shaped bowl into another through a tiny hole not unlike those in water jars. Hourglasses were used as far back in history as water jars and stayed in use until recent times. Indeed, egg-timing glasses which run one, two, or three minutes, made on the model of the larger hourglass, may be bought in stores to-day.

The hourglass had to be transparent, for one must see the sand flowing; but glass was made by the Egyptians early in their history. A sandglass had many things to recommend it. It was cheap, which the water clock was not. It would not freeze or spill over. It did not need refilling. It could be carried about, as Father Time carries his, although it was clumsy for that purpose. Athenians, however, used these glasses as we use watches.

One of the most interesting later uses of the sandglass was in the British and American navies of a couple of hundred years ago. A little glass was made which would run out in twenty-eight seconds. When it was desired to find the speed at which a vessel was going, a log line was thrown out at the rear in which knots had been tied at regular intervals of forty-seven feet and three inches. This number of feet and inches would go in a nautical mile as many times as twenty-eight seconds would go in an hour. So the line was allowed to run out, with one sailor watching for the knots to appear while another sailor watched the twenty-eight-second glass. By counting how fast the knots appeared, they could reckon how many "knots," or nautical miles an hour, the vessel was making. Distance at sea is still calculated by "knots," a system which goes back to the rope with knots tied in it and the tiny sandglass for a time measure.

While the sandglass was convenient and cheap, it had the disadvantage of being so bulky and heavy that it could measure time only for short periods. It served its purpose well, but it never really competed with the "water-thief."

Our next clock story swings us over a thousand and more years, out of ancient and classic times into the more familiar Middle Ages. The darkest period of the Middle Ages, following the fall of the Roman Empire, has passed. The incoming of barbarians from the north is centuries past. The crusades are long over. King John of England has granted his Magna Charta; Marco Polo has rediscovered the mysterious lands of Cathay and the Orient, of which knowledge had almost disappeared in the Dark Ages; and Columbus has found a new continent in his search for a passage to these ancient lands. Printing has been invented, and the new birth of learning and art and science is coming all over Europe.

Such learning as there is has been treasured all these years in the monasteries of the church. While battles were raging, and the Turks were threatening to sweep over Europe, amid all the turmoil and the ignorance of the Dark Ages, patient, scholarly monks had tried to keep the torch of learning flickering in their retreats. It is probably to these monks that we owe the special interest in clocks from 1200 A.D. on. The very name "clock" comes from the French word for bell, "cloche," and suggests to us the frequent bells ringing out in the monastery to call the monks to prayers. King Alfred the Great had invented the candle clock, in which he made circular lines on a candle and then let it burn slowly to mark the hours, because he had made a vow to give eight hours out of each twenty-four to acts of religion, eight hours to rest and recreation, and eight hours to public affairs. If the monks were to lead a regular life, they had to have some kind of timepiece to mark the hours. Gerbert the Monk, who afterward became Pope Sylvester Second, is credited in the ninth century with having made some kind of a device with weights and wheels which seemed to the authorities to be so likely to indicate a knowledge of magic and therefore an alliance with the Evil One, that they banished him from France for a time because of it.

By the thirteenth century real clocks began to be made here and there; some of them are to be seen to-day in museums or on the old cathedrals. A famous one by Henry De Vick was set up in 1364, which was run by shifting weights on a balance. On this clock the signal for the massacre of St. Bartholomew was struck. The great change in clock making which marks the beginning of clocks not unlike those of our own day comes near the end of the sixteenth century, in the time of Queen Elizabeth, of Shakespeare, of Drake, and Sir Walter Raleigh. This change began with a great moment in the life of that distinguished astronomer, inventor, and scientist, Galileo, who lived from 1564 to 1642, and changed the thought of the world in many ways.

Galileo was an Italian, born in Pisa, and early fascinated by studies into the laws of the world. He was to make the first thermometer. It is said that he was the first to turn the telescope on the heavens and make by its means certain revolutionary discoveries. He was counted mad by the people of his day when he taught in the schools that the sun was the center of the universe and the earth moved about it. By dropping balls of different weights from the Leaning Tower of Pisa, he discovered the laws of falling bodies. Of all the discoveries that he made none was more interesting in its practical use than the one he made when he was a boy of seventeen and stood in the cathedral watching a swinging lamp.

The lamp, hung by a long chain from the ceiling, swung to and fro as the currents of the air moved it. Sometimes with a strong breeze from the opening of a door it swung through a long sweep. Again it moved but slightly in the air. Others were moving about the cathedral at the moment when the swing of the lamp caught the attention of the lad. Thousands of people had sat and seen those lamps swing. But Galileo was the first to notice that whether the lamp swung through a wide part-circle or through a small one, the swing took just the same length of time. At least he thought it did. So he put his finger on his pulse and counted its beats for a timepiece. It proved as he thought. From the minute when the chain hung straight down in the center to the minute when it came back to the center from its swing, the time was the same, whether it swung through a long arc or a small. Thus was discovered the law of the pendulum, which was to change the whole scheme of clock making.

GALILEO DISCOVERING THE PRINCIPLE OF THE PENDULUM When only seventeen, Galileo timed the swinging of a lamp in the Cathedral of Pisa by his pulse and thus discovered the law upon which pendulum clocks are built.

Galileo did not himself make a pendulum clock, though he did suggest some fifty years later that it might be done. His mind was on other studies. Between 1657 and 1665 Christian Huyghens, a celebrated Dutch astronomer, did make a pendulum clock, and others soon followed his example.

In order to understand what the pendulum did for the clock, we must see how modern clocks are made. A clock must have motive power to make it run. The old water clock used water. In the clocks of the Middle Ages the power came from the dropping of a weight. If you have ever wound a grandfather’s or "tall" clock, you know that by winding you lift to the top weights which have been slowly dropping all the week. A clock must have some mechanism, too, for using the power to run the cords: wheels, a pulley, or something of the sort. That is, the power must be harnessed to turn some sort of machinery. It has to have, also, some kind of a clock face or pointer to show the time. The water clock and even the sundial had that. Last, but not least, it has to have some kind of a device to regulate the use of the motive power, so that it will run the machine at exactly an even rate all the time. That is where the old clock makers had their troubles. The weights ran down too fast or too slowly, or the wheels turned at uneven rates. Here is where the pendulum came in. With its even swing back and forth, always at the same rate, it could regulate the speed at which the machinery turned and keep the clock going at an even rate.

The next great improvement was to substitute for the heavy weights a closely coiled spring, which would gradually unwind. The unwinding of the spring gave the motive power, which had been supplied earlier by water falling or weights dropping. This made a small clock or a watch possible.

With the recent coming of clocks and watches for everyone’s use, the modern age in which we live really begins. Our whole world is run by timepieces. Schools and factories, trains, shops, and homes are all managed on a system of time keeping by which every man’s life fits closely into other lives. Without clocks and watches the modern world could hardly run. It has been well said, "The Middle Ages made clocks and watches; and clocks and watches make the age in which we live."

Back in the days of the Middle Ages when so many wonderful things were being found out, people began to think that they could do anything if they only knew how. Doctors found that certain medicines would work wonderful cures, and began to wonder if there was not a medicine (an "elixir," as they called it) which would keep people young or make them live forever. Alchemists worked in their secret rooms, as Boettger of Dresden did, to find out a process that would turn iron or some other common metal into gold and so make them and their patrons rich.

It is not strange that when people discovered what wonderful things machines would do, they wanted still more wonderful machines. Their machines did man’s work for him. They were self-running, too, for a time. But if the water wheel was to be kept at work running the mill, water had to be running in the stream. The clock had to be wound. Every machine had to have a man step in once in a while and do something to keep it going. If we could only make a machine that would go of itself forever, the machine makers said. So all through the Middle Ages we find some worker here or there possessed by the impossible idea that he might start a machine going that would never stop, a perpetual motion machine.

We of the twentieth century, who have learned more of the laws of matter and force and energy, know that we cannot create perpetual motion machines. But we do know that Nature works in very long terms. To us human beings who live for only a short term of years, it seems as if with Nature as with God a thousand years are looked upon as a day in the cycle of the universe. So by harnessing Nature to do our work for us, we can make something that will keep going long after we are gone.

In our own time radium has been discovered. Radium is a very active element which is going to pieces within itself and changing into something else. This sounds a little like the old alchemist’s idea that iron could be changed into gold. We are finding out facts that would astonish the alchemist and perhaps make him say, "I told you so; I always knew it could be done." Changes in radium happen very slowly. A radium atom is going to pieces; that we know. The scientist thinks it will take a single, tiny atom two thousand years to go wholly to pieces, to change into something else. Now do you see how we are going to make the title of our story come true?

A Scientist has made a clock which is run by the action of radium as it breaks up. Radium takes the place of the weights or the coiled spring. The radium atom has been "wound up" for us by Nature; it is slowly "unwinding" or going to pieces. Radium in that clock is harnessed to the works. The clock has not had to be wound in all the years since the radium was set in it. Radium holds itself together in somewhat the way in which a coiled spring stays coiled. But the spring unwinds slowly, and the radium breaks up very, very slowly. If the radium keeps on "unwinding" year by year at the same slow rate, and no accident, like fire or an earthquake, befalls the place where the clock stands, the clock will go two thousand years. If it stops, the trouble will be that man’s machinery in the clock has worn out or got disconnected. The radium will not stop doing its part.

The Chinese knew early in their history the power of iron touched by a lodestone to point always north and south. Before 1000 A.D. we know from their writings of their placing a bar of magnet iron in the arms of a wooden figure on a pivot. The arm of the little man or the spear of iron which he held in his hand would give the direction. But the Chinese were a stay-at-home people. The Arabs had to journey half round the world to find them. They brought the idea of the compass home with them. The people of Europe probably learned it from the Arabs at the time of the Crusades. An Arabian writer of 1242 A.D. says that "captains who sail the Indian seas use a fish made out of hollow iron which when thrown into water swims upon the surface and points out north and south with its head and tail." Crusaders in the twelfth and thirteenth centuries report the Arabian "House of the Needle."

The real mariner’s compass with its compass card for navigation was ready for use by 1300 and 1400. Then the age of exploration could begin. With the faithful little needle in its box Vasco da Gama, Columbus, and all the other bold adventurers could start off on their voyages. The compass probably made more change in the world than any other early invention. Almost it made a new world.

Compass Card

The hourglass and the clock gave man a new sense of time and a new control over his use of it. The compass gave him a new sense of direction. As the sun is the natural timekeeper for the world, so the sun, moon, and stars are the natural compasses for the world. By their positions a man can learn to judge not only what time it is but which way he is moving at a given time. But the sun, moon, and stars might be shut out from his sight by a fog for weeks at a time. With the clock he could know the time by day and night. With the compass in his hand he could move freely across trackless waters and barren stretches of desert, sure always of the direction in which he was moving. The little piece of magnetized iron was the best friend the sailor ever gained. And the sailor opened up the world for the rest of mankind.

Old-time sailors did not understand the compass even while they used it. We of to-day know that the earth is the real magnet, and that its magnetic poles at the north and the south pull the lesser magnets. The mariner’s compass has been developed into a wonderfully fine and accurate instrument. It is still of constant service to mankind.

In our day, while this compass is our mainstay, two new kinds of compass have been added. One works on the principle of a top. Watch a top the next time you see one spinning, and notice that so long as it keeps going it keeps the same slant. Only when it slows down does it begin to tip and wobble back and forth. The gyro-compass or the spinning compass takes this law that the axis (a line from the tip to the point) of a top will always point in the same direction if it can, and uses it in a compass. If a spinning compass is pointed to the north star in the morning and keeps on spinning all day, the earth may swing around on its daily circle beneath it and the ship may twist and turn on the waters. That compass will keep on pointing to the north star. On an iron ship a magnet compass has to be watched to see what the pull of the iron in the ship may do in swinging its course out of the true line. The spinning compass cares nothing for iron. It heads to the north star.

The Gyro-Compass or Spinning Compass

With the coming of radio, man can talk through the air without wires. A ship at sea can talk to a lighthouse on land. A man on a ship, with a radio compass, sends out a question through the dark, foggy night, "Where am I?" The man may be fifteen hundred miles from shore. A radio station in one port sends out its signal. Another station a hundred or two miles down the shore sends out its signal. By those two reports, coming through the air, the man with his radio compass and his chart of the waters in which he is sailing can draw a triangle on his chart in which those two stations are two points of the triangle and his ship is at the third point. In this way he can figure out exactly where he is.

The ways of the sea are always a mystery to the landsman. We look at the sailor’s compass and radio compass, at his charts and other guides, without much understanding of how they tell him what he needs to know. But this we can understand, that to-day man travels on the open sea, on vast spaces of blue water with no guides or landmarks to help him, by as safe and sure a route as if he were walking on land. By the compass he gained his first great victory over space.