WATER.—PHYSICAL PROPERTIES.
A glance at the map of our earth at once reveals the preponderance of water. Three-fourths of its surface is covered by the ocean, and if we divide the globe into northeastern and southwestern halves, one of the hemispheres will consist almost entirely of water. Yet there was a time when the ocean was still more extensive and covered islands and continents; even the loftiest mountain peaks were beneath the sea. We shall presently see how important an agency water became in moulding the earth and making it habitable for man. The lakes and rivers also constitute no small part of many lands, and even in the air, invisible streams are ever flowing, for “all the rivers run into the sea; yet the sea is not full; unto the place from whence the rivers come thither they return again.” The summer’s heat is the power, and the air its instrument, by which vapors, fogs, clouds and rain are lifted and borne back to the mountains and again scattered over the plains.
WATER SEEKING ITS LEVEL.
WATER AS AN ARCHITECT—WORLD-BUILDING.
In the divine hand water has been used as the material with which to shape the earth, even as a workman employs his files, emery and diamond dust to shape the objects upon which he labors. At first the earth was characterized by one dead level—a wide, desolate, fire-scarred plain; then the mountains were upheaved, the depths were broken up, and, no longer resting in their quiet beds, everywhere rolled down the slopes, and by mere attrition, wore away the firm rocks and bore the material into the plains below; all valleys have thus been made. Some are still in process of formation. Far out in the Gulf of Mexico, and in the Indian Ocean, the Mississippi and the Ganges are pouring their sediment and building future continents. Sometimes, where the volume of water was great, or the mountains steep, mighty gorges were carved out, like the river-bed below Niagara, the tremendous cuts of the Congo, or the awful cañons of the Colorado, some of which are five thousand feet in depth. Ceaseless waves beat upon the shore, powdered the rocks, and made the soft beaches; tides ebbed and flowed, and slowly wrought their changes. In addition to the wearing action of the water, which arises from the smoothness of its molecules, and the slight cohesion of its particles, thereby causing ceaseless motion, it possesses a wonderful solvent power. Solution arises from the fact that the adhesion between a liquid and a solid is greater than the cohesion between the molecules of the solid; whenever this is the case the latter will be dissolved. If water is heated, this action will be intensified; such was its condition in the early geologic ages, and this explains the extraordinary rapidity with which rocks were then dissolved. Beautiful grottoes were formed like that of Antiparos, vast caverns, such as those along the coasts of Scotland, the Mammoth Cave of Kentucky, and the Wyandotte of Indiana. It is a curious paradox which appears in this story of world-building that the New World was really the oldest in process of formation, and that the tallest mountains were the latest upheaved.
WATER TRANSMITS POWER EQUALLY IN ALL DIRECTIONS.
WATER AS AN ARTIST.
If we will stop and remember for a moment how often the painter and poet dwell upon variety in landscapes, we shall appreciate more fully the artistic work of water. We have already seen that by dissolving the rocks, the way was prepared for all verdure, and not less truly did it round the hills and carve the gorges, as well as smooth the outlines, which add so much to nature’s charms. Nor is this all. In the running brook, the sparkling cascade, the white foam of the cataract, the deep blue of the sea, the matchless variety and beauty of the clouds, we may behold the grandest exhibitions of color and form. There is endless variation in the tint, light and shade of water, owing to many causes. That this is true one will easily see in studying Church’s “Icebergs,” a picture of wonderful color and beauty, although one would scarcely expect these qualities in such a subject. Time would fail to describe the numberless forms of beauty displayed by water; it glitters in the dewdrop, shimmers in the wave, rounds the cheek of beauty, colors the rose, and paints the rainbow on the arching sky.
WATER AS A LABORER.
Water was early made to labor for man. Of the various forms of energy which he employs, animal, steam, electricity, wind, water, the last is probably the most inexpensive. It is a singular fact that all national progress and efficiency have depended largely upon proximity of water. Seas, indenting bays, sounds, rivers early bore the commerce of the world, and formed the medium for interchange of ideas, inventions, arts and literature. The little peninsulas of Italy and Greece, with their broken coast-line, developed a hardy race of seamen, who penetrated to the remotest parts of the then known world. The story of the Argonauts in search of the Golden Fleece is one of the earliest, as it is one of the most beautiful traditions of antiquity.
CAPILLARY ATTRACTION—WATER AND QUICKSILVER.
Look at that sturdy little island in the north Atlantic, whose people have so utilized the ocean that “she has dotted the surface of the whole globe with her possessions and military posts, whose morning drum beat, following the sun and keeping company with the hours, circles the earth daily with one continuous strain of the martial airs of England.” We build many hopes for the prosperity of our own country upon the fact of our extensive coast-line, which gives us one mile of shore-line to every one hundred and four square miles of surface, while that of Europe, which is far more favored in this respect than any other division of the world, has only one mile of coast for every two hundred and twenty-four square miles of surface. Water furnishes the most convenient and mobile instrument for applying gravity. As it flows on its way to the sea, everywhere it is made to turn the thousand busy wheels of industry, so that it used to be said that every pound of water in the Blackstone and Merrimac rivers did a pound of work before it reached the sea. The physical property of water which makes it in this connection so useful is, that it presses equally in all directions; it can therefore be adjusted with great ease to the sinuosities of tubes, water-wheels and kindred appliances. We also use it as a convenient power for obtaining pressure by means of the hydrostatic press.
THE HYDROSTATIC PRESS—PRESSING COTTON.
This depends upon the principle that water transmits force equally in all directions; therefore, strange as it may appear, we meet the paradox that a little water will accomplish as much as a great quantity. Thus, if a slender upright tube be connected with the bottom of a large tank the water will stand at the same height in both, and consequently the trifling amount of water in the tube supports and balances the vast amount in the tank. Suppose the area of the tube were as one to ten thousand. Now, if we should apply the force of one pound on the surface of the water in the tube, an uplifting force of one pound would be communicated to every equal area of a piston resting upon the surface of the water in the tank; so it is evident that with the pressure of one pound we might raise ten thousand pounds.
There are few more interesting proofs that “Peace hath her victories, no less renowned than war,” than that found in the completion of the Erie Canal, whereby a path was made for the vast agricultural products of the west to the metropolis, and thence to all countries.
Re-read the story of that magnificent commemoration of human genius and effort, when, in New York harbor, Governor DeWitt Clinton joined in perpetual wedlock the lake and the sea.
An interesting illustration of the upward pressure of water in seeking its level may often be seen in the dry docks of our great seaport cities, where old ocean is frequently compelled to do heavy work for man by lifting his ships out of water. A vessel is on the shoals; after the storm has subsided a great number of empty air-tight casks are sunk around the ship and fastened to it. The gradual pushing of the water lifting against the casks slowly raises the vessel until she floats.
SHOWING AN ORDINARY PUMP.
WATER AS A LAPIDARY.
Allusion has already been made to the erosive action of water. Every day observation will furnish us examples of this. The pebbles beneath our feet have been rounded and polished by this lapidary. The most beautiful specimens of its handiwork, however, are to be found in crystallization. Snow exhibits many lovely forms. If the flakes are caught on any dark surface we shall readily see that they are fashioned with great symmetry, starlike in form, on the plan of six diverging rays. There is an endless variety formed by additions made to these primaries. Not less beautiful are many of the forms of ice. The Mer-de-Glace of the Alps is pronounced by Prof. Tyndall one of nature’s most resplendent pieces of handiwork. If we may judge from all descriptions, the lofty spires and glittering sides of an iceberg furnish a spectacle sublime and terrible. The vast ice fields of the North, in spite of all their desolation, possess a mysterious charm.
The most favorable condition for the crystallization of any substance is its solution in water. It will thus appear that water is one great source of that marvelous beauty of form which we find in the mineral world. This process of nature may readily be repeated by dissolving alum, sugar, and similar substances, and crystallizing them on glass, or a string placed in the solution, and allowed to remain undisturbed. Bouquets of crystallized grasses are made in this way, often being colored afterward.
Almost all mineral substances can be crystallized, and some of the finest observations of the microscopist are made upon these objects.
Among the most interesting phenomena produced are those of polarized light, and many important deductions in medicine and chemistry are derived therefrom.
WATER AS A FARMER.
Solids are not the only substances which water is capable of taking to itself. Gases are also absorbed by it. A pint of water under one pressure of the atmosphere will absorb one pint of carbonic acid. It will take seven hundred pints of ammonia gas. This power of absorption belonging to water is of the greatest importance to agriculture. As the rain descends it frees the air from noxious gases, and carries them to the earth, where they are distributed to the rootlets of the plants; in this instance that which is death to the animal is life to the plant; it also rises in all vegetation, from cell to cell, by what is known as endosmosis. It moves freely through the porous earth by capillary attraction, the interstices of the earth really constituting a system of tubing through which the liquids freely circulate. When the earth becomes compact and hard the water can not so freely move through it; if the weather is dry, then follows another important result—the air, which always bears with it more or less moisture, especially in hot weather, can not pass through the soil and bring to the roots its gift of nutrition. Any one can perform the following experiment: Walk into the garden some morning when the season is dry and hot. You will often notice that the garden walk looks damp, while the spot that you hoed the day before, perhaps, seems dry, but if you will dig down a little way into each you will find that the loosened earth where you had worked, is moist, while the former is, below the surface, quite dry. Hence a practical inference of much value—the importance of frequently hoeing and loosening the earth, to facilitate the growth of plants, especially when the season is dry. The philosophy of this is, that the air freely passing through the loosened earth becomes cooled, and the moisture it contains is condensed, and remains to nourish the plant. A curious illustration of this fact is found in the prolific growth of watermelons, which are raised with the greatest success in dry sand, which is often so hot on the surface as to be painful to the hand; and yet a hundred pounds of watermelon contain ninety-eight pounds of water. The agricultural value of a country depends as much upon its water supply as upon the excellence of its soil. Here again we find one of the grandest endowments of “our heritage.” This is a land of sweet and abundant waters. Even those portions once considered worthless have been made of immense value by irrigation. Through our pastures flow crystal streams for the advantage of the dairy, as the production of good butter depends as much upon pure water as it does upon sweet grasses.
MANY FORMS OF SIPHONS.
Glance over one of the broad corn-fields of the West. What a wonderful contrivance is each stalk for gathering sunlight and moisture! Water constitutes eighty per cent. of that vast growth! The forces of the sunbeam, which are locked up in it, will be surrendered during the coming winter, to sustain and invigorate man and beast. Take two large goblets, one of which is nearly filled with water. Place on it a piece of card-board, through which a hole has been made, pass through the opening the roots of any growing plant, like a spray of bergamot. Cover the plant with the other goblet; in a few moments the inner surface of the upper goblet will be covered with moisture, showing that the roots have absorbed and the stomata or pores of the leaves have exhaled the moisture. In every land drouth is synonymous with want and famine. With glad festivals the Egyptians greet the rising of the Nile. The seven lean years of Joseph’s time were years of drouth. If M. De Lesseps should carry out his mighty project of overflowing the Sahara with the waters of the Mediterranean, that desert may yet bud and blossom like the rose. Growth is intimately connected with climate, and the latter depends not a little upon proximity to water. The beautiful lake region of the United States would be almost uninhabitable were it not for the gentle influence of these inland seas. They cool the air in summer and warm it in winter, thus forming a great equalizing influence and preventing extremes of temperature.
WATER AS PHILANTHROPIST.
Few things are more interesting and suggestive of a kind Providence than the plan by which water is supplied to the human family by underground currents, where it is kept cool in summer, and prevented from freezing in the winter. Natural pipeage is found almost everywhere in the earth, consisting of a layer of sand or gravel found between layers of clay or rock, which are practically impervious to water.
Where the upper layer is wanting springs appear. They often gush from the foot of the hills, but not unfrequently we find them on lofty summits. Human skill has sought for these hidden streams at great depths by means of Artesian wells, some of which are two thousand feet deep. It is claimed that the Chinese used them two thousand years ago for procuring gas and salt water. There is a famous Artesian well at Grenelle, Paris, which yields six hundred and fifty-six gallons of water per minute, while two of these wells in Chicago discharge four hundred and thirty-two thousand gallons a day. As Chicago is situated on a level prairie, this water must come from the high hills of Rock River, a hundred miles away. The water coming from these great depths is warm, one proof of the heated condition of the interior of the earth.
Horticulturists have in some places conducted this heated water by underground pipes through their gardens, and thus produced a semi-tropical vegetation.
Human contrivances for lifting water to higher elevations are various. Archimedes invented a screw for this purpose. The siphon, the chain pump, the ordinary lifting pump, the force pump, and some other inventions are applied to do this work. It would be a profitable exercise to study out the philosophy of these water lifters. You can also make them for yourself. The illustration of the forms of siphons and their various uses, for example, as given in this article, will well repay careful study.
SHOWING THAT PRESSURE DEPENDS UPON DEPTH.
Another way in which water acts as a friend to man, is in its hygienic effects. Think of the numberless uses of ice in summer, and how grateful to the fevered lips is ice! The invalid seeks in summer the cool sea breeze, freighted with its finely divided and stimulating salts and mineral vapors. In winter the genial atmosphere of Florida or the Gulf will fan the patient’s faded cheek. Or perhaps some health resort may be sought where there are mingled with the waters valuable medicinal restoratives. Vermont has the greatest number of these, but they are found at Sharon, Avon, Clifton, and Saratoga; while the hot springs of Arkansas have a great reputation, and who knows but what in some of the wonderful bath fountains of the West we may yet find what Ponce de Leon sought, the elixir which should transform old age into blooming youth. The latest new idea in medical practice is the hot water cure, which consists in drinking an indefinite amount of hot water whenever opportunity makes it possible. Public fountains are good temperance lectures.
SHOWING THE PRINCIPLE OF ARTESIAN WELLS.
One must travel in oriental lands, however, to learn all the sweet and beautiful significance of that one word, Water, which is so often used in the Bible as the best symbol of God’s abounding mercy.
Note.—The cuts in this article are from “Elements of Physics,” by Prof. A. P. Gage, the richest contribution to experimental philosophy printed in many years. Teachers as well as students will find it full of valuable suggestions.