Chap. 5.] Nature's devices for raising Water. 505 CHAPTER V. Nature's devices for raising water-Their influence-More common than other natural operations— The globe a self-moving hydraulic engine-Streams flowing on its surface-Others ejected from its bowels--Subterranean cisterns, tubes and siphons-Intermitting springs-Natural rams and pressure engines-Eruption of water on the coast of Italy-Water raised in vapor-Clouds-Water raised by steam-Geysers-Earthquakes-Vegetation-Advantages of studying it-Erroneous views of future happiness-Circulation of sap-This fluid wonderfully varied in its effects and movements-Pitcher plant and Peruvian canes-Trees of Australia-Endosmosis-Waterspouts-Ascent of liquids by capillary attraction-Tenacity and other properties of liquids-Ascent of liquids up inclined planes-Liquid drops -Their uniform diffusion when not counteracted by gravity-Their form and size-Soft and hard soldering-Ascent of water in capillary tubes limited only by its volume-Cohesion of liquids-Ascent of water through sand and rags-Rise of oil in lamp wicks and through the pores of boxwood BEFORE taking leave of artificial machines for raising water, a few of the most prominent of those which nature employs may be noticed; for, after all, the best of human contrivances are but imitations of hers. The extent to which raising of water is carried by nature is wonderful. Persons who have not reflected on the subject would hardly suspect the influence which this operation exerts on our globe; yet it is one which the Creator has adopted to bring about results upon which the happiness of all things living depend. To the elevation of water into the atmosphere, and its return to the earth, the formation of continents and islands, lakes, rivers, fountains, valleys, plains, gravel, sand, mould, &c. are due. The fertility of soil, growth of vegetables, and life of animals, are also to be attributed in a greater or less degree to the same source. Of nature's machinery, devices to raise, diffuse and collect water are the most common. They pervade all her works-the most magnificent and the most minute: and if we turn our thoughts to the world at large and contemplate it as a whole, we find it performing the part of an immense hydraulic engine, one which never stops working, and whose energy never flags. In almost every point of view this feature is obvious. In its exterior our planet is rather aqueous than terrene. Three-fourths of its surface are sunk into basins and scooped into channels for the reception and transmission of water; more than one-half is occupied by the ocean, the principal reservoir; while the other half is intersected in every direction by lakes, rivers, and rivulets innumerable, that convey the dispersed liquid back to the sea. The motion imparted to water also exhibits every degree of activity and agitation, from overwhelming torrents and mountainous waves, to the gentle shower that descends as if dropt through the finest cullender, and the placid stream that glides imperceptibly by. Sometimes we behold it running with the speed of a race horse, roaring among rapids, leaping over precipices and darting down cataracts— here dashed into spray, there churned into foam; now winding in eddies and gyrating in whirlpools; passing through channels whose paths are tortuous as those of a serpent, and shooting through others straight as an arrow. Open channels and reservoirs constitute, however, but a part of nature's hydraulic machinery. In the interior of the earth, are close and air-tight reservoirs, and tubes of every imaginable size and figure, and of incon 506 Natural Siphons-Pressure Engines-Vapor. [Book V. ceivable strength. These receive and transmit liquid columns whose hydrostatic pressure would shiver the strongest conduits made by man, while the volumes of water that play within and pass through them render utterly insignificant all the products of artificial engines. We know that rivers sometimes discharge themselves into subterraneous tubes, which, transporting the fluid to a distance, again vomits it up. In this manner water is often conveyed to places where its appearance is difficult to account for, because of the level of all the neighboring regions being far below the aperture of discharge-this being sometimes on the summit of mountains, and often at their sides. But the transmission of water from one level to another through pipes, is one of the simplest operations in natural as it is in artificial hydraulics. The flexure of the tubes fabricated by nature convert some of them into siphons, and these often decant the contents of caverns in which water slowly accumulates. The liquid rises till it flows over the highest bend in the tube, and the siphon being thus charged continues in operation, like one of ours, until the reservoir that supplies it be emptied, or the contents reduced to a level with the external orifice of the discharging leg. The action then ceases until the cavern be again filled and the operation renewed. Hence intermitting springs, and some of those that ebb and flow. Natural machines analogous to water-rams, pressure engines, and fountains of compression are doubtless also in operation in the bowels of the earth. In the intricate and infinitely variegated chasms and fissures through which water is falling and gases collecting, the principles of these machines must necessarily be often excited, and on scales of magnitude calculated to strike us with awe. It is not improbable that some of those horrible eruptions mentioned in history and others that have occurred at şea without human witnesses were effected by machinery of this description. The subaqueous eruption which occurred on the south-west coast of Italy, in 1831, was probably an example. A column of water, 800 yards in circumference, was forced to an elevation of sixty feet, and an island formed of the solid materials displaced. snow. But natural devices are not confined to such as raise liquids by the momentum they acquire in flowing through tubes, or oscillating in waves, nor by the hydrostatic pressure of one volume transmitted by means of airs to another. There are some in which water is raised by solar heat. The liquid is converted into steam or vapor, in which state it is rendered lighter than air, and consequently ascends. This may be considered as nature's favorite plan. It is in operation everywhere, and always. By it water is drawn from every part of the earth's surface-both sea and land, and by it oceans of the liquid are kept suspended above us in the form of clouds, until it again returns in showers of rain and drifts of hail and Of the quantity thus elevated, we may form some rude idea from the calculations of Halley respecting that drawn daily from the surface of the Mediterranean, viz. between five and six millions of tons! a result which he deduced from experiments. Every person knows that canals require an extra supply of water to meet the expenses of evaporation. By experiments on the canal of Languedoc in France, the annual quantity thus borne off was found to be nearly three feet in depth over its whole area. Clouds of vapor or steam are often observed hanging over marshy ground, until the wind rises and bears them away. In hot seasons copious steams may be seen ascending just after a shower; but in general aqueous vapor thus generated, is invisible as it is impalpable. In clear weather, we are not sensible of its presence or of its movements. Chap. 5.] Water raised by Steam-Vegetable Kingdom. 507 We literally live in it, as in the spray of a fountain, but our perceptions are too gross to detect it. How simple is this mode of raising water, and yet how effective! How silently does it work, and yet how sure! In its liquid state, water is too heavy to be suspended in the firmament; hence the Creator has made this provision to attenuate its particles by heat. It then rises upwards of its own accord-neither wheels nor cranks, pumps, pistons, pipes, nor even power is required to send them up, or to keep them there; and yet billions of tons are rising every hour, and accumulating in masses so great as to baffle language to describe or thought to grasp. And, what is equally remarkable, neither cisterns are required to contain, nor conduits through which to convey them. The phenomenon teaches us how a heavier fluid may be suspended in a lighter one, and that the proposition of water being 800 times heavier than air, is only conditionally truedepending merely upon the state in which those fluids are ordinarily exhibited to us. To increase our admiration, the salt water of the ocean is during the process of elevation distilled into fresh, thus furnishing among other suggestions that by which navigators have often adopted to sustain life in the extremities of thirst. Water is also continually being converted into vapor and urged into the atmosphere by subterranean heat. Our planet may be considered, as indeed it was by the ancients, as a cauldron, in which steam is generated by those fires whose flues are volcanos. Oceans of the liquid are incessantly but silently thrown up from this cause. But, as might be expected, from the intricate arrangement of internal chambers and channels of communication, steam must often accumulate in cavities until its elasticity drives up the water that seals the passage to the surface. Hence boiling and thermal springs, and hence also the hot spouting springs of Iceland. According to Olafsen, a Danish traveler, one of the Geysers exhibited a jet at one time 19 feet in diameter and 360 feet high! Modern authors explain the phenomenon of earthquakes by the accumulation of steam in the bowels of the earth. Plutarch says the Stoic philosophers did the same; but long before Zeno appeared the opinion prevailed, and caused the epithet "shaker of the earth" to be given to Neptune. The mechanical as well as chemical operations going on within the earth, are wonderful in their nature and terrible in extent. Well might mythologists locate the workshops of the gods there, and place the forges of Vulcan and the Cyclops at the base of volcanos. Of contrivances for raising, liquids, as developed in the organization of animals, we took some notice in the second and third books. Most if not all of them may be considered modifications of bellows and piston pumps. In the vegetable kingdom, other devices, and such as are based on other principles, are in active operation. This portion of creation exhibits in a striking light the important part which devices for raising water perform in the constitution of our globe. Every tree and every plant, from the towering cedar of Lebanon, to the hyssop that springeth out of the wall, from the wide-spreading banyan to a wheaten straw or melon vine, is a natural pump, through whose tubes water is drawn from the earth or imbibed from the air. There is something exceedingly pleasing and sublime in the contemplation of the growth of vegetables, the germination of seeds, appearance of sprouts, development of stems, branches, leaves, buds, blossoms, flowers, and fruits-their variegated forms, dimensions, movements, colors, and odors. Some persons who have never turned their attention to this subject till the evening of their days, have been astonished at the wonders which 508 Ascent of Sap. [Book V. burst on their view. A new state of existence seemed to open upon them. Their perception and estimate of things were changed. Instead of considering the world as calculated only for what man too generally makes it-a -a scene for the display and gratification of the most groveling and sordid passions, they find it a theatre crowded with enchanting specimens of the Creator's skill, the study of which imparts the sweetest pleasure, and the knowledge of which constitutes the greatest wealth. Those pious but mistaken people, who incessantly murmur against the world, and long to depart from" this howling wilderness," as they are pleased to term it, reproach their Maker by reviling his work. They are waiting for future displays of his glory, and neglect those ravishing ones by which they are surrounded, forgetting that "the whole earth is full of his glory"-looking for sources of pleasure to come, and closing their eyes on those before them-thirsting for the waters of heaven, and despising the living fountains which the Father of all intellects has opened for them on earth. They seem to think happiness hereafter will not depend upon knowledge, or that knowledge will be acquired without effort-a kind of passive enjoyment, independent of the exercise of their intellectual or spiritual energies. But they have no ground to hope for any such thing. Reasoning from analogy and the nature of mind, the happiness of spirits must consist in being imbued with a love of nature-in contemplating the wisdom and other attributes of the Deity, as they are unfolded in the works of creation. In what else can it consist? It is not probable that human or finite beings of any class can ever know God except through the medium of his works. It is admitted that the study of nature is a source of exquisite pleasure to intelligent beings, and the most refined one too that the mind can conceive: it is also one that can never be exhausted. Those persons, therefore, who take no pleasure in examining the works of creation here, are little prepared to enter upon more extensive and scrutinizing views of them in other worlds. If they have no relish for an acquaintance with the Creator's works while they live, they have no right to expect new tastes for them after death. The works of God are all perfect; those in this world as well as those in others; and he that can look with apathy on a tulip or a rose, a passion flower or a lily, or any other production of a flower garden or a forest, has not begun to live. Besides, we are not sure that other worlds possess more captivating or more ennobling subjects for contemplation and research-more thrilling proofs of the wisdom and beneficence of God. The circulation of sap (sometimes called the blood of plants) is one of the most interesting of natural phenomena. It is connected with some of the most delightful feelings of our nature, and with the activity and joys of the brute creation. When in spring its action commences, a sensation of buoyancy pervades all organized beings. The earth begins to put on her richest attire-her inhabitants rejoice in her approaching splendor, and exult in view of the feasts preparing for them. On the other hand, when in autumn her freshness fades and her glory withers, all feel the change. How infinitely varied are the effects of sap and the energy of its movements! Rushing to the summit of the tallest trees, and lingering in the grass of our meadows-shooting up perpendicularly in the poplar and pine, horizontally in the branches of the baobab and oak, and descending in those of the Indian fig-tree and willow. In some plants, accumu'ating chiefly in their roots, as in the turnip, radish, and potato, and emerging above ground in cucumbers and melons-ascending higher in the bushes of currants and gooseberries, and ranging over those in apple Chap. 5.] Natural Pitchers-Trees in Australia. 509 and pear trees. By what wonderful process is sap distilled into liquid honey in the maple, and into wine in the grape ' e? How is it elaborated into fruits of every flavor, and exhaled in perfumes from sweet scented herbs, and in what manner does it contribute to produce every imaginable color and tint in flowers? By what means does sap form a natural vase in the pitcher plant, and then enter it as limpid water, along with rain and dew? This singular production of the vegetable kingdom collects water from the earth and atmosphere in vessels of the same consistence and color as the leaves. Each pitcher is strengthened by a hoop, and furnished with a cover or lid that turns on a fibrous hinge. When dew or rain falls, this cover opens; and as soon as the weather clears, it closes and prevents the water that entered from being wasted by evaporation. There are other plants which store up water much in the same way. Such were the reeds that relieved Alvarado (one of the conquerors of Peru) and his companions from perishing of thirst. Garcilasso, in his Commentaries observes, "The information they had of the water was from the people of the country, who guided them to the canes, some of which contained six gallons, and some more." We know that the juices of plants cannot be raised without force, and that this force must be increased with the elevation to which the liquid is to be lifted. Animals exert a muscular power in working the pumps formed in their bodies, and these machines they put in motion at will. This is not the case with vegetables: yet sap, the pabulum of their life, is elevated to the tops of the highest trees, and apparently with the same facility as it is diffused through microscopic plants. That the force by which this is done is not latent or negative in its nature, is clear, since it may easily be rendered manifest. Cut a branch from a vine in the spring when the sap is rising, and stretch a piece of india rubber over the end of the part that remains, secure it by thread wound round the stump, so as to exclude the air and prevent the wound from healing. In a little while the caoutchouc will be swelled or bulged out by the exuding fluid, and it will continue to swell, however thick it may be, till it burst. A few years ago we treated in this way some branches of an Isabella grape vine, and afterwards applied to one of them a close vessel containing mercury, in which the lower end of a long glass tube was immersed with a view to measure the force excited. In four days the mercury rose 36 inches in the tube, being pushed up by the sap which took its place in the vessel; and but for an accident, by which the apparatus was broken, it would probably have ascended still higher. But this force, great as it was, is small when compared with that which sends the fluid through trees that grow on the Australian continent and islands. Some of these resemble single tubes, and are filled with a semifluid or soft pith. Tasman, the discoverer of Van Dieman's Land, found trees there whose lowest branches were between 60 and 70 feet above the ground. The French expedition sent in search of the lamented Perouse, found on Cocos island a tree nearly 100 feet high, and only three inches in diameter. It was of so hard a texture, that it resisted at first the heaviest blows of an axe; and when the pith was taken out, the thickness of the wood did not exceed of an inch-forming a perfect tube. But this tree was only half the height of some others in the same regions; for several were seen whose diameters were only seven or eight inches, and whose tops towered upwards of 200 feet above the earth! The force that drives sap to such elevations is wonderful indeed; and could it be applied as a mechanical agent, it would be resistless as steam. It might |