The earth and its wonders

Front matter

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II. Tli^ Earth^s $hape

IF the earth which we inhabit is not flat, as the ancients suppose, and as many even of its present inhabitants believe, what is its actual shape ? As you have already learned, the earth is globular. It is not, indeed, a perfect globe, but so nearly so that were we to see an exact model of its shape, the eye would discern no difference between it and a perfect sphere. It is slightly flattened at the poles, as if you should take between your two hands an orange perfectly globular, and thus apply to it the slightest pressure. Then the diameter from one hand to the other would be an atom less than another diameter across this one at right angles to it. This difierence between the two diame-

THE EARTH'S SHAPE. 23

ters thus represented, is about twenty-six miles. This, though considerable of itself, is, however, a very small quantity when compared to nearly eight thousand miles, the length of the earth's diameter ; and the proportion of the two diameters is thus exactly ' as three hundred and one to three hundred and two. It is not necessary to suppose that this was the exact shape of the earth when first created, or that this shape was otherwise than a perfect sphere ; for, had it been such at the beginning, its swift and constant motion, in entirely revolving upon its axis every twenty-four hours, would naturally and gradually tend to withdraw the material of the earth from the poles toward the equator, thus forming a slight protuberance in the equatorial regions at the expense of the polar regions.

The process may be well illustrated by imagining a knitting-needle thrust, at the stem, directly through an orange ; the two ends of the needle would represent the north and south poles of the earth. Now, immerse the orange in a vessel of oil, and then whirl it rapidly on the needle as its axis, and mark the result. The oil will be measurably drawn away from around the needle at either end, and sHghtly heaped up on the part of the orange which is equidistant from the two poles, that is, upon the equator.

In the first chapter of the Bible, where we read the Mosaic account of the creation of our earth as it now appears, we have the globe represented as previously being entirely covered with water. If, as is quite probable, it was then, and afterward, revolving upon its axis, the phenomenon above noticed, of the diminishing of the polar substance and a corresponding accumulation at and around the equator, would have been a certain consequence.

Our earth, then, is of globular shape, notwithstanding it has the seeming of a vast plain ; and it will not be difficult for you to comprehend why it has this appearance. It is because of its prodigious extent. Were we to stand on a great ball of a mile in diameter, and three miles around it, we should not seem as now to be standing upon a plain, but, looking hither and thither, we should observe the surface of the ball gradually curving downward in every direction from the point where we might be standing, while, at the distance of a

THE EARTU'S SHAPE. 2$

quarter of a mile, more or less, the surface would sink entirely from our sight.

Not at all so, however, as we stand on this immense ball which we call the earth. Here, on whatever plain or ocean we may be, there is no perceptible curvature downward within the reach of our vision, and hence, wherever we may walk or sail, the aspect is that of an immense plain, varied on the open sea by nothing, and interrupted on the land only by hills or forest, as it stretches away to the far horizon.

III. Batth^s $hape Illustrated*

OME of you may not as yet have clearly understood how it is ascertained that our world is a globe, since it has scarcely any appearance of being such. There are several very clear and conclusive proofs of this great fact. Let us, in the first place, undertake a long imaginary journey, and as this our journey is to be imaginary, we will start from where we please, and take just the direction we please. The city of Washington, then, shall be our point of departure, and precisely west shall be our direction. Of course we shall go on this line sheer across the continent, and come, some day, to San Francisco. Here, taking one of the steamships now constantly plying the great Pacific Ocean, we will 26

EARTH'S SHAPE ILLUSTRATED. 2/

continue our course due west, and come in about twenty days to Jeddo, in Japan. Thence, still going due west, we will take passage across the Japan and Yellow seas, and starting from Pekin, in China, we will continue our far western way over Asia and the Hellespont to Constantinople ; whence, by land and sea, still westward we will reach Lisbon, in Portugal ; where, embarking with our prow exactly west, we will cross the Atlantic, and, landing at the mouth of Delaware Bay, and proceeding overland, we will come to Washington again, the place of starting on this long, long journey. We have gone from Washington, on a due western course, 25,000 miles, and, instead of being all that distance away from the city, we are at it again. We went out from the western side, and, without changing our course, we have come to the eastern side of the same city — that is, we have gone round the world from Washington to Washington.

And now perhaps some one will answer me that I have proved the world to be round in an eastern and western direction, but this does not prove it to be so on a northern and south-

28 THE EARTPI AND ITS WONDERS.

ern line ; and it has never been sailed around by way of the North and South Poles, and probably never can be. Well, then, let us adopt another criterion. If we can not by reason of ice and cold go to the poles and pass beyond them, let us, in our second journey, go as far as possible. We will select the same starting place, the city of Washington, and lay our course, this time, due north instead of west. The latitude of Washington is very nearly 39°, and before starting we will direct our eyes exactly to the northern horizon, and then elevate them the same number of degrees, 39°, and note a little star lying there, called the North Star.

We will take with us a little instrument adapted to the purpose of noting the height of the stars above the horizon. Starting on our due northerly course, we presently reach Montreal, in Canada ; and then, with our instrument, we ascertain that our North Star, instead of remaining at 39°, as when we started, has somehow lifted itself up full six degrees, and stands at 45°. How is this ? Continuing our journey nearly seven hundred miles north from Montreal, and again sighting

EARTH'S SHAPE ILLUSTRATED. 29

our guiding star, lo, it has ascended ten degrees further up toward the zenith. How can this be true of a star that we thought was always stationary ? Only thus : it is not that our star has gone upward, but that we, in coming a thousand miles from Washington, have been all the time going downward. For had we been traveling upon a horizontal plane all along this northern tour, the star which, at Washington, was only 39"^ high, would still remain at the same elevation. But we have been traveling on an arc, instead of a straight line, and as on this arc we have gone downward under the star, the latter, by the same amount exactly, has gone upward. And should we go on to the pole itself, the North Star will stand directly overhead.

This means that the path from Washington to the North Pole is an arc ; and the same is true of a path to the pole from any other point. That is, the north and south of the earth are globular as well as the east and west ; and this means that the whole is globular.

IV

IHERE is another consideration as much or more convincing, going to show that our earth is globular instead of being flat, cylindrical, or of any other shape. We refer to eclipses of the moon. You have doubtless learned that these eclipses are caused by the earth passing directly between the sun and moon, so that the huge shadow of the earth, projected out into space, hits the moon. And if the three centers, namely, those of the sun, moon, and earth, are in a straight line, when the earth falls between the sun and the moon, the latter will be wholly obscured by the earth's shadow, and continue so for two or three hours. On the other hand, if, in making the passage between the two

EARTH'S SHAPE ILLUSTRATED. 31

luminaries, the earth fails to pass precisely between them, but its center rises a little above or falls a little below, the straight line joining the other two centers, then the earth's shadow will strike only a part of the moon, and it will, consequently, be but partly eclipsed. Now this shadow of the earth on the moon, when the latter is eclipsed, is always and invariably cwcular. It never has a straight side, never has an angle, never is a mere line across the moon's face, never is concave, never any other shape than exactly circular and convex. And what is the shape of that object that, in any and all directions in which you can place it, forever casts such a shadow.^ To this question there is but one answer. It is a globe, and can be nothing else.

Other considerations might be adduced leading to the same conclusion ; but these are sufficient, and we may settle it in our minds as absolutely certain that the earth which we, for the present, inhabit, is a great globe or ball hanging in the mid heavens. It is also an undoubted fact that the heavenly bodies around us, the sun itself, the moon, the planets, -and all the stars of the firmament, are of similar shape. Some of these approach nearer the form of a perfect sphere, some others not so near ; but the globular shape, more or less perfect, they all doubtless possess.

Why the great and all-wise Creator has given to ours and other worlds this characteristic shape is probably but partially known to us. But that there were very important and sufficient reasons for this we may be fully assured. He does nothing in vain, or capriciously, or wantonly, and without ample reasons ; and though we, with all our eager penetration, can see but a part of His ways, a very small part, yet a reason or two for the sphericity, or globular shape of the worlds, may not be beyond the perception of mortals.

These great worlds, and ours with the rest, though apparently so stationary and still, are in motion ; and this motion is a flight through space so swift and awful as to be utterly and immeasurably beyond every human conception. And it is very likely, if not quite certain, that the globular shape is best adapted, if not indispensable, to the regularity and safety of such motion. Then, as to our globe, it is certain that this "round

EARTH'S SHAPE ILLUSTRATED. 33

world " is far better adapted to its purposes, especially to the convenience, comfort, and even the safety, of animal nature, than any other conceivable form. To suppose the earth to have had given to it a cubical figure would be to suppose the greatest part of it uninhabitable. At least two out of the six sides would doubtless have been as desolate as the polar regions of the globe now are, while the eight corners would have projected themselves into space, a sort of pyramidal mountains, many leagues in height, the drear abode of everlasting snow, and storms, and whirlwinds, and utter desolation.

On the other hand, had the earth, instead of being a globe, been an immense plain as it actually appears to be, the present law of gravitation and the daily revolution upon its axis remaining as now, it is not easy to conceive how, not merely the animal creation, but the earth itself, could escape confusion and ruin. 3

V. Th^ Barth^s i^im«nsians♦

UR world, then, is a ball. This is easy to say or write, but who may ever portray, or even begin to imagine its prodigious dimensions? A simple process of mathematics will give^us the measurements, and we can write down the figures that express these measurements, and we can look at the figures and ponder them, and essay to imagine what they actually express. But all in vain. .

But let us glance a moment at the measurements. First, let my young friends form a clear idea of what is termed a great circle of the earth. It is a circle or circumference drawn around the earth in any direction, so as to divide it into two equal parts. Thus the equator is an example of a great circle. We 34

THE EARTH'S DIMENSIONS. 35

will suppose one of these great circles drawn around the earth at right angles to the equator, and, of course, passing through the North and South Poles. We call such a circle as this a meridian. We will now take a position on this meridian at 40° north latitude, and with our eye on the North Star, we will travel north until the star shall stand at 41° instead of 40°. As the star has ascended one degree, so we have traveled just one degree along the great circle. Here we will stop and travel back to the place of starting — measuring, as we go, the distance between the two points. Completing the measurement, we find the distance to be sixty-nine and one-half miles. This is the length of one degree of a great circle of the earth, by actual, careful, and exact measurement. Now, as in every circle there are 360 degrees, if we multiply this length of one degree by three hundred and sixty, we shall have the whole extent of the circle, 25,020 miles. This, then, is the maximum or greatest distance around this ball called earth. From this we deduce, by the ratio of the diameter and circumference of a circle, that the earth's diameter — its distance from one side, through the center, to the opposite side— is about eight thousand miles.

But what human mind can form any conception of these tremendous measurements or distances ? Sometimes in traveHng we discern an elevation seeming far, very far away in the dim distance before us. By a great effort our minds can, perhaps, take in all the long path leading to that object. Yet it is a conception of only about thirty miles, and this long reach, that requires so positive an effort to conceive adequately, must be multiplied to eight hundred and thirty-three times in order to extend around this enormous globe. A train of cars flying a mile a minute would require seventeen days and a third of a day to traverse the amazing circuit.

Such is the circumference and such the diameter of this ball on which we dwell. And if you wish to proceed further, and ascertain the extent of its whole surface, you have only to find, first, the extent of the surface, or area of the great circle, which is obtained by multiplying its circumference, 25,000 miles, by half its radius or one-fourth of its diameter, 8,000 miles, and you have, in round numbers,

THE EARTH'S DIMENSIONS. 37

for the area of this great circle, 50,000,000 of square miles. Then, as multiplying the area of a great circle of a ball by four gives the area of its whole surface, you will thus have 200,000,000 of square miles as the measure of the earth's surface. Now if we wish to proceed a step further, and ascertain the solid contents of our world, the process is direct and simple. We have the surface in square miles, 200,000,000 ; we have the diameter in linear miles, 8,000. We have only then to multiply the surface by half the diameter, 4,000, and afterward divide the product by three, and we shall have the mass of our globe in solid miles. How this is so, you will ascertain by the study of geometry. So, by the above multiplying, we shall find the solid contents to be nearly 260,000,000,000 of cubic or solid miles. All this inconceivable mass is under your feet as you walk and play, and spreads itself afar before and behind you, and is the great theater of your present but transient dwelling-place.

VI. Earth's ^wpierficial IHmensions

AM unwilling to dismiss this idea of the immensity of our earth without an attempt or two to illustrate further its inconceivable dimensions. And although all that may be said and written and pictured will never avail to lift our imaginations hardly a step toward the great result, yet it may serve to gratify an innocent and laudable curiosity to endeavor, by one and another contrivance or illustration, to approximate toward some feeble conception of the earth's magnitude.

Our preceding sketch, then, has proved the

surface of this globe to comprise 200,000,000

of square miles. One square mile is an easy

conception. In the Western land surveys, it

EARTH'S SUPERFICIAL DIMENSIONS. 39

comprises what is termed a section, and contains six hundred and forty acres — a farm of large dimensions. If you have never seen such a square of land, yet you have in your minds the idea of a mile as it extends along the road that passes your home. From your house to a certain neighbor's is just about a mile, and you have often traveled it, and call up in your minds the whole path with its little turns, its trees, its ups and downs, and each intervening house and brook. You know what a mile is. So if there were a square plain inclosed by a fence along each of its four sides, and each of the four fences were a mile long, you could stand by one of these fences or over in the center of the great lot, where each fence would be a half mile distant, and thus receive into your mind a tolerably fair idea of the magnitude of one square mile. But if, instead of standing in the center of one square mile, you should stand in the center of a hundred of such, where each fence at its nearest point would be five miles ofi', and, of course, scarcely visible, your idea of this one hundred square miles would be very imperfect, while your comprehension of a thousand of such would be entirely inadequate. What, then, of ten hundred thousand, or a million ! What of this million multiplied two hundred fold ! Yet this is the earth's great surface ! Who can imagine it ? Who can begin to do so ?

Now let us return to our one square •mile, of which we have so perfect an idea. We will cross it from one fence to the opposite fence. If we walk as fast as men usually walk when going to and from their business, we shall cross the lot in twenty minutes, and should cross three such lots in an hour, and, of course, thirty of them in ten hours, by which time we should be weary, and we should have walked far enough for the day, and would need to rest till to-morrow. Now if we should walk on at the same rate till we had regularly crossed every square mile of the earth's surface, we should be more than 18,000 years old before we finished the enormous tramp, and should we propose to be more particular, and so cross not only each square mile, but each acre of this vast landscape, at the same rate, we should be occupied ten hours every day through 12,000,- 000 of years.

Or should we propose for ourselves a more

EARTH'S SUPERFICIAL DIMENSIONS. 4 1

speedy and superficial survey of this globe of ours, we will suppose ourselves accommodated with a comfortable seat about a mile aloft in the air, the seat to be stationary while the earth under us is turning eastward in its daily revolution. We will choose a position such that a belt of the surface five miles wide shall pass under us and by us, until in each twenty-four hours every such belt of five miles has been successively passed, and been inspected by us as it glided onward. Much of the earth, it is true, will rush beneath us with a velocity that will be frightful to contemplate — houses, trees, lakes, rivers, hills, and plains flying eastward with double the swiftness of a cannon-ball, and we shall need to be wide awake or our observations will be superficial indeed. Yet such an examination, comprising but the merest glance of a moment, will occupy us, in the swift and vast survey, every hour, minute, and second of more than eight long years.

VII

ROM such calculations and imaginings let us venture a glance away from the surface of this great world, and endeavor to penetrate down amid the unfathomable recesses of its awful bulk. While the earth is globular in shape, it is not, like the artificial globes in the schools, a hollow and empty shell, but is a solid mass, with an average weight of about five times that of a globe of water of equal dimensions.

We have seen that while the earth's surface comprises 200,000,000 of square miles, its mass or bulk comprises 260,000,000,000 of cubic or solid miles. Here again, and here especially, we are lost, and all human ideas and computations are at fault and vain. 42

EARTH'S SOLID DIMENSIONS. 43

We have scarcely more conception of this stupendous mass of our earth than has a worm on the sides of Mont Blanc of that huge and awful eminence. Two hundred and sixtyseven thousand millions of sohd miles! Suppose that, in our imagination, we take out one of these solid miles and set it up bodily and in shape on some wide-spread plain. What an object and what a wonder! A mile along, a m.ile through, a mile aloft ! In vastitude what is comparable to it among all the works or erections of man ?

The greatest of the Egyptian pyramids has a square base of seven hundred and forty six feet on a side, covering about thirteen acres, and was originally about five hundred feet in height, while the weight of this huge structure was seven and one-half millions of tons. And yet, to erect our supposed edifice of one solid mile would require fifteen hundred and twenty-five just such pyramids. Were the great pile hollow, and divided into stories each ten feet in height, and allowing a square yard for each person, it would contain within its walls more than 1,600,000,000 of people, or a third more than all the present inhabitants of the earth.

Look at it: on a favorable day it could be seen a hundred miles away. It is within a few hundred feet of the height of Mt. Washington, in New Hampshire. Place another solid mile upon the top of this, and you have the height of Mt. ^tna. Place still another upon the top of these, and there looms up the awful altitude of Mont Blanc, the loftiest mountain of Europe. And yet these are only three out of the 260,000,000,000 of just such enormous cubes. Now remove the two upper cubes and leave the first one as before. It is solid and comprises a certain amount of matter — such an amount as that to remove this one solid mile a distance of twenty miles would require? through seventy-five years, 100,000 men and 200,000 horses. Once more: were this globe of ours resting upon another globe precisely similar, its weight, in tons, pressing upon the other globe would be expressed by the number 5,842x10^^ that is, 5,842 multiplied by ten raised to the eighteenth power, that is, 5,842,- 000,000,000,000,000,000, or 5,842 millions of millions of millions of tons.

Of this almost infinite weight you and I, of course, know nothing. We have no conception

EARTH'S SOLID DIMENSIONS. 45

of even a single one million of all this countless number of millions. The great mathematician, Archimedes, once boasted that if he had a place to stand upon separate from the earth and independent of it, where he might arrange and apply his apparatus, he could move this vast globe. But some curious inquirer setting himself to investigate the matter, came to the conclusion that even were such a feat at all within the limits of possibility, some millions of years would be consumed in moving the globe to the amount of a single inch. How overwhelming, then, is the thought of that Omnipotent Being who can take up this immense world as a "very little thing;" who upholds it "by the word of his power;" who, in the beginning, hurled it away on its swift and everlasting flight around its central sun, and who causes it to perform an entire revolution upon its axis every twenty-four hours !

VIII. The Earth^s motions

jHE closing remarks of my preceding sketch allude to the fact that this earth, so immeasurably large and heavy, and apparently so still and stationary, is, however, in motion. As suggested, it has two great and principal motions ; one around the sun, and the other a rolling motion upon its axis, like the revolution of a top. Its motion around the sun is of terrible swiftness, and one of these revolutions makes our year. Being about 95,000,000 of miles from the sun, its circuit or orbit around it is more than six times that distance, or about 580,000,000 of miles. This would be 1,600,000 miles every day, about 67,000 miles an hour, and 18J miles every second. 46

THE EARTH'S MOTIONS. 47

Think of such an enormous world flying through space at so fearful a rate. Could we stand off somewhere a thousand miles from the earth and see it go by us at that distance, what an awfully magnificent spectacle would be presented to us ; and who could ever compute the force that drives the world through its great circuit forever ? Where resides that force? Only with one Being in all the universe, and that same Being has us in his hands and sacred keeping from moment to moment, and can exert the same power for our loftiest happiness.

But while the earth is thus flying around the sun, and thus making our year, it has, at the same time, a rolling motion upon its axis, making our day of twenty-four hours. A top spinning upon the floor, and at the same time circling around the room, well illustrates this double motion of our earth. And while its motion around the sun, as we have just noticed, is so terribly swift, this motion upon its axis is much less so, but still of greater rapidity than that of any motion upon its surface; for a ball like this great earth can not roll sheer over in twenty-four hours without a motion upon the highest portions of its surface far swifter than we have ever witnessed. The rail-cars under full way go by us at the rate, sometimes, of forty miles an hour ; and how sublimely swift, then, is their course ! How soon they are away in the far distance ! In rare instances, their speed is increased to the rate of sixty miles an hour, a mile a minute. But this is a terrible speed, whether we are on board or witnessing it from outside. The pigeon's flight is not far from a hundred miles an hour, and that of a cannon-ball is probably five or six times greater, which, by the earth's daily revolving upon its axis, people on and near the line of the equator are, every hour, borne, by its stupendous rolling, a thousand and forty miles eastward, or i/f miles every minute, or a mile in less than four seconds. Proceeding north or south from the equator toward the poles, the circles or parallels become less, as you will see by looking upon an artificial globe ; so that, in rolling over of the globe, the people living on these small circles traverse, in the twenty-four hours, a less distance than those residing on or near the equator. At 20° either way from the equator,

THE EARTH'S MOTIONS. 49

for example, the circle surrounding the earth corresponding to the 20th parallel of latitude, instead of being, as at the equator, 25,000 miles around, is about 23,400 miles. At 30° it is 21,600, at 40^ it is 19,080 miles, and at 50° it is 15,840 miles. Consequently, in the daily revolution of the earth upon its axis, those living at or near 20° north and south latitude, are carried eastward, not at the rate of 17! miles a minute as at the equator, but 16 J miles ; and those living at 30° go 15 miles a minute, or a mile in four seconds ; those at 40^ go 13 J miles a minute, while, up at the 50th parallel, the velocity per minute is just 11 miles. So the rate of speed goes on diminishing toward the poles ; while, if a man shall, sometime, stand upon the north pole — and there is a man or boy living who will stand there — and if he should stand perfectly still for twenty-four hours, and not turn to right or left, he will not be carried a mile nor an inch by the rolling over of the earth, but will simply be turned clear around, his face, as the globe goes round, turning successively in every direction toward the horizon.