Physical Geography of the Sea and its Meteorology/Chapter 10

by Matthew Fontaine Maury

CHAPTER X.

§ 461-499.—THE SALTS OF THE SEA.

461. The brine of the ocean.—The brine of the ocean is the ley of the earth (§ 43). From it the sea derives dynamical power, and its currents their main strength. Hence, to understand the dynamics of the ocean, it is necessary to study the effects of their saltness upon the equilibrium of its waters; wherefore this chapter is added to assist in the elucidation of what has already been said concerning the currents and other phenomena of the sea. Why was the sea made salt? It is the salts of the sea that ill part to its waters those curious anomalies in the laws of freezing and of thermal dilatation which have been described in a previous chapter (IX.). It is the salts of the sea that assist the rays of heat to penetrate its bosom;^[1] but for these, the solar ray, instead of heating large masses of water like the Gulf Stream, would play only at or near the surface, raising the temperature of the waters there, like the sand in desert places, to an inordinate degree. The salts of the sea invest it with adaptations which it could not possess were its waters fresh. Were they fresh, they would attain their maximum density at 39°.5 instead of 25°.6, and the sea then would not have dynamical force enough to put the Gulf Stream in motion, nor could it regulate those climates we call marine.

462. Were the sea of fresh water.—Were the sea fresh and not salt, Ireland would never have presented those ever-green shores which have won for her the name of the "Emerald Isle;" and the climate of England would have vied with Labrador for inhospitality. Had not the sea been salt, the torrid zone would have been hotter and the frigid colder for lack of aqueous circulation; had the sea not been salt, intertropical seas would have been at a constant temperature higher than blood heat, and the polar oceans would have been sealed up in everlasting fetters of ice, while certain parts of the earth would have been deluged with rain. Had the seas been of fresh water, the amount of evaporation, the quantity of rain, the volume and size of our rivers, would all have been different from what they are; the quantity of electricity in the air would have been permanently changed from what it is, and its tension in the sky would have been exceedingly feeble. In the evaporation of fresh water at normal temperatures, but little of that fluid is evolved; while vapour from salt water carries off vitreous, and leaves behind resinous electricity in abundance. Hence, with seas of fresh water, our thunder-storms would be feeble contrivances, flashing only with such sparks as the vegetable kingdom might, when the juices of its plants were converted into vapour, lend to the clouds. It might seem strange, this idea that the thunderbolt of the sky, the sheet-lightning of the clouds, and the forked flashes of the storm, all have their genesis chiefly in the salts of the sea, and so it would be held were it not that Faraday has shown that a single grain of water and a little zinc can evolve electricity enough for a thunder-clap; therefore, were there no salts in the waters of the ocean, the sound of thunder would scarce be heard in the sky^[2]—there would be no Gulf Stream, and no open sea in the Arctic Ocean.

463. Uniform character of sea water.—As a general rule, the constituents of sea water are as constant in their proportions as are the components of the atmosphere. It is true that we sometimes come across arms of the sea, or places in the ocean, where we find the water more salt or less salt than sea water is generally; but this circumstance is due to local causes of easy explanation. For instance: when we come to an arm of the sea, as the Red Sea (§ 376), upon which it never rains, and from which the atmosphere is continually abstracting, by evaporation, fresh water from the salt, we may naturally expect to find a greater proportion of salt in the sea water that remains than we do near the mouth of some great river, as the Amazon, or in the regions of constant precipitation, or in other parts, as on the polar side of 40° in the North Atlantic, where it rains more than it evaporates. Yet in the case of the Red Sea, and all such natural salt-pans, as that and other rainless portions of the sea may be called, there is, on account of currents which are continually bearing away the water that has given off its vapours and bringing forward that which is less concentrated as to brine, a moderate degree of saltness which its waters cannot exceed. We moreover find that, though the constituents of sea water, like those of the atmosphere, are not for every place invariably the same as to their proportions, yet they are the same, or nearly the same, as to their character. When, therefore, we take into consideration the fact that, as a general rule, sea water is, with the exception above stated, everywhere and always the same, and that it can only be made so by being well shaken together, we find grounds on which to base the conjecture that the ocean has its system of circulation, which is well calculated to excite our admiration, for it is as wonderful as the circulation of the blood.

464. Hypotheses.—In order to investigate the effect of the salts of the sea upon its currents, and to catch a glimpse of the laws by which the circulation of its waters is governed, hypothesis, in the present meagre state of absolute knowledge with regard to the subject, seems to be as necessary to progress as is a cornerstone to a building. To make progress with such investigations we want something to build upon. In the absence of facts, we are sometimes permitted to suppose them; only, in supposing them, we should take not only the possible, but the probable; and in making the selection of the various hypotheses which are suggested, we are bound to prefer that one by which the greatest number of phenomena can be reconciled. When we have found, tried, and offered such a one, we are entitled to claim for it a respectful consideration at least, until we discover it leading us into some palpable absurdity, or until some other hypothesis be suggested which will account equally as well, but for a greater number of phenomena. Then, as honest searchers after truth, we should be ready to give up the former, adopt the latter, and hold it until some other better than either of the two be offered. With this understanding, I venture to offer an hypothesis with regard to the agency of the salts or solid matter of the sea in imparting dynamical force to the waters of the ocean, and to suggest that one of the purposes which, in the grand design, it was probably intended to accomplish by having the sea salt, and not fresh, was to impart to its waters the forces and powers necessary to make their circulation complete. In the first place, we rely mainly upon hypothesis or conjecture for the assertion that there is a set of currents in the sea by which its waters are conveyed from place to place with regularity, certainty, and order. But this conjecture appears to be founded on reason, and we believe it to be true; for if we take a sample of water which shall fairly represent, in the proportion of its constituents, the average water of the Pacific Ocean, and analyze it, and if we do the same by a similar sample from the Atlantic, we shall find the analysis of the one to resemble that of the other as closely as though the two samples had been taken from the same bottle after having been well shaken. How, then, shall we account for this, unless upon the supposition that sea water from one part of the world is, in the process of time, brought in contact and mixed up with sea water from all other parts of the world? Agents, therefore, it would seem, are at work, which shake up the waters of the sea as though they were in a bottle, and which, in the course of time, mingle those that are in one part of the ocean with those that are in another as thoroughly and completely as it is possible for a man to do in a vessel of his own construction. This fact as to uniformity of components appears to call for the hypothesis that sea water which to-day is in one part of the ocean, will, in the process of time, be found in another part the most remote. It must, therefore, be carried about by currents; and as these currents have their offices to perform in the terrestrial economy, they probably do not flow by chance, but in obedience to physical laws; they no doubt, therefore, assist to maintain the order and preserve the harmony which characterize every department of God's handywork, and as such we treat them.

465. Arguments afforded by corallines in favour of.—This hypothesis about currents is based upon our faith in the physical adaptations with which the sea is invested. Take, for example, the coral islands, reefs, beds, and atolls with which the Pacific Ocean is studded and garnished. They were built up of materials which a certain kind of insect quarried from the sea water. The currents of the sea ministered to this little insect—they were its hod carriers. When fresh supplies of solid matter were wanted for the coral rock upon which the foundations of the Polynesian Islands were laid, these hod-carriers brought them in unfailing streams of sea water, loaded with food and building materials for the coralline. The obedient currents, therefore, must thread the widest and the deepest seas, for they never fail to come at the right time, nor refuse to give place and go after they have ministered to the hungry creature. Unless the currents of the sea were employed to carry off from this insect the waters that have been emptied by it of their lime, and to bring to it others charged with more, it is evident the little creature would have perished for want of food long before its task was half completed. But for currents, it would have been impaled in a nook of the very drop of water in which it was brought forth; for it would have soon secreted the lime contained in this drop, and then, without the ministering aid of currents to bring it more, it would have perished for the want of food for itself and materials for its edifice; and thus, but for the benign currents which took this exhausted water away, there we perceive this emptied drop would have remained, not only as the grave of the little architect, but as a monument in attestation of the shocking monstrosity that there had been a failure in the sublime system of terrestrial adaptations—that the sea had not been adapted by its Creator to the well-being of all its inhabitants. Now we do know that its adaptations are suited to all the wants of every one of its inhabitants—to the wants of the coral insect as well as to those of the whale. Thus our simple hypothesis acquires the majesty of truth, for we are now prepared boldly to assert we know that the sea has its system of circulation, because it transports materials for the coral insect and its rock from one part of the world to another; because its currents receive them from the rivers, and hand them over to the little mason for the structure of the most stupendous works of solid masonry that man has ever seen—the coral islands of the sea. Thus, and moreover, by a process of reasoning which is perfectly philosophical, we are irresistibly led to conjecture that there are regular and certain, if not appointed channels through which the water travels from one part of the ocean to another, and that those channels belong to an arrangement which may make, and which, for ought we know to the contrary, does make the system of oceanic circulation as complete, as perfect, and as harmonious as is that of the atmosphere or the blood. Every drop of water in the sea is as obedient to law and order as are the members of the heavenly host in the remotest regions of space; for when the morning stars sang together in the almighty anthem, we are told "the waves also lifted up their voice" in chorus; and doubtless, therefore, the harmony in the depths of the ocean is in tune with that which comes from the spheres above. "We cannot doubt it; for, were it not so, were there no channels of circulation from one ocean to another, and if, accordingly, the waters of the Atlantic were confined to the Atlantic, or if the waters of the arms and seas of the Atlantic were confined to those arms and seas, and had no channels of circulation by which they could pass out into the ocean, and traverse different latitudes and climates—if this were so, then the machinery of the ocean would be as incomplete as that of a watch without a balance-wheel.

466. Ditto by the Red Sea.—For instance, take the Red Sea and the Mediterranean by way of illustration. Upon the Red Sea there is no precipitation; it is a rainless region; not a river runs down to it, not a brook empties into it; therefore there is no process by which the salts and washings of the earth, which are taken up and held in solution by rain or river water, can be brought down into the Red Sea. Its salts come from the ocean, and the air takes up from it, in the process of evaporation, fresh water, leaving behind, for the currents to carry away, the solid matter which, as sea water, it held in solution. On the other hand, numerous rivers discharge themselves into the Mediterranean, some of which are filtered through soils and among minerals which yield one kind of salts or soluble matter, another river runs through a limestone or volcanic region of country, and brings down in solution solid matter—it may be common salt, sulphate or carbonate of line, magnesia, soda, potash, or iron—either or all may be in its waters. Still, the constituents of sea water from the Mediterranean and of sea water from the Red Sea are quite the same. But the waters of the Dead Sea have no connection with those of the ocean; they are cut off from its channels of circulation, and are therefore quite different, as to their components, from any arm, firth, or gulf of the broad ocean. Its inhabitants are also different from those of the high seas. "The water which evaporates from the sea is nearly pure, containing but very minute traces of salts. Falling as rain upon the land, it washes the soil, percolates through the rocky layers, and becomes charged with saline substances, which are borne seaward by the returning currents. The ocean, therefore, is the great depository of everything that water can dissolve and carry down from the surface of the continents; and, as there is no channel for their escape, they of course consequently accumulate."^[3] They would constantly accumulate, as this very shrewd author remarks, were it not for the shells and insects of the sea. and other agents mentioned.

467. A general system of circulation required for the ocean.—How, therefore, shall we account for this sameness of compound, this structure of coral (§ 465), this stability as to animal life in the sea, but upon the supposition of a general system of circulation in the ocean, by which, in process of time, water from one part is conveyed to another part the most remote, and by which a general interchange and commingling of the waters take place? In like manner, the constituents of the atmosphere, whether it be analyzed at the equator or the poles, are the same. By cutting off and shutting up from the general channels of circulation any portion of sea water, as in the Dead Sea, or of atmospheric air, as in mines or wells, we can easily charge either with gases or other matter that shall very much affect its character, or alter the proportion of its ingredients, and affect the health of its inhabitants; but in the open sea or open air we can do no such thing.

468. Dynamical agents.—The principal agents that are supposed to be concerned in giving circulation to the atmosphere, and in preserving the ratio among its components, are light, heat, electricity, and perhaps magnetism. But with regard to the sea, it is not known what office, if any, is performed by electricity, in giving dynamical force to its system of circulation. The chief motive power from which marine currents derive their velocity has been ascribed to heat; but a close study of the agents concerned has suggested that an important—nay, a powerful and active agency in the system of oceanic circulation is derived from the salts of the sea water, through the instrumentality of the winds, of marine plants, and animals. These give the ocean great dynamical force. Let us, for the sake of illustrating and explaining the nature of this force, suppose the sea in all its parts—in its depths and at the surface, at the equator and about the poles—to be of one uniform temperature, and to be all of fresh water; and, moreover, that there be neither wind to disturb its surface, nor tides nor rains to raise the level in this part, or to depress it in that. In this case there would be nothing of heat to disturb its equilibrium, and there would be no motive power (§ 461) to beget currents, or to set the water in motion by reason of the difference of level or of specific gravity due to water at different densities and temperatures. Now let us suppose the winds, for the first time since the creation, to commence to blow upon this quiescent sea, and to ruffle its surface; they, by their force, would create partial surface currents, and thus agitating the waters, as they do, but only for a little way below the surface, would give rise to a feeble circulation in the supposed sea of fresh water. The surface drift thus created—currents they would hardly be,—would set with the wind, giving rise to counter movements in the shape of under-tows and eddies. This, then, is one of the sources whence power is given to the system of oceanic circulation; but, though a feeble one, it is one which exists in reality, and, therefore, need not be regarded as hypothetical. Some (§ 79) think it the "sole cause!" Let us next call in evaporation and precipitation, with heat and cold—more powerful agents still. Suppose the evaporation to commence from this imaginary fresh-water ocean, and to go on as it does from the seas as they are. In those regions, as in the trade-wind regions, where evaporation is in excess of precipitation (§ 545), the general level of this supposed sea would be altered, and immediately as much water as is carried off by evaporation would commence to flow in from north and south towards the trade-wind or evaporating region to restore the level. On the other hand, the winds would have taken this vapour, borne it off to the extra-tropical regions, and precipitated it, we will suppose, where precipitation is in excess of evaporation. Here is another alteration of sea level by elevation instead of by depression; and hence we have the motive power for a surface current from each pole towards the equator, the object of which is only to supply the demand for evaporation in the trade-wind regions—demand for evaporation being taken here to mean the difference between evaporation and precipitation for any part of the sea. Now imagine this sea of uniform temperature to be suddenly stricken with the invisible wand of heat and cold, bringing its waters to the various temperatures at which they at this instant are standing. This change of temperature would make a change of specific gravity in the waters, which would destroy the equilibrium of the whole ocean; upon this a set of currents would immediately commence to flow, namely, a current of cold and heavy water to the place of the warm, and a current of warm and lighter to the place of the cold. The motive power of the currents thus created would be difference of specific gravity arising from difference of temperature in fresh water. We have now traced the effect of two agents, which, in a sea of fresh water, would tend to create currents, and to beget a system of aqueous circulation; but a set of currents, and a system of circulation which, it is readily perceived, would be quite feeble in comparison with those which we find in the salt sea. One of these agents would be employed in restoring, by means of one or more polar currents, the water that is taken from one part of the ocean by evaporation, and deposited in another by precipitation. The other agent would be employed in restoring, by the forces due to difference of specific gravity, the equilibrium, which has been disturbed by heating, and of course expanding, the waters of the torrid zone on one hand, and by cooling, and consequently contracting, those of the frigid zone on the other. This agency, would, if it were not modified by others, find expression in a system of currents and counter currents, or rather in a set of surface currents of warm and lighter water, from the equator towards the poles, and in another set of under currents of cooler, dense, and heavy water from the poles towards the equator.

469. Currents without wind.—Such, keeping out of view the influence of the winds, which we may suppose would be the same whether the sea were salt or fresh, would be the system of oceanic circulation were the sea all of fresh water. But fresh water, in cooling, begins to expand near the temperature of 40°,^[4] and expands more and more till it reaches the freezing-point, and ceases to be fluid. This law of expansion by cooling would impart a peculiar feature to the system of oceanic circulation were the waters all fresh, which is not necessary here to notice farther than to say it cannot exist in seas of salt water, for salt water (§ 405) contracts as its temperature is lowered, and until it passes its freezing-point. Hence, in consequence of its salts, changes of temperature derive increased power to disturb the equilibrium of the ocean. If this train of reasoning be good, we may infer that, in a system of oceanic circulation, the dynamical force to be derived from difference of temperature, where the waters are all fresh, would be quite feeble; and that were the sea not salt, we should (§ 462) probably have no such current in it as the Gulf Stream. So far we have been reasoning hypothetically, to show what would be the chief agents, exclusive of the winds, in disturbing the equilibrium of the ocean were its waters fresh and not salt. And whatever disturbs equilibrium there may be regarded as the primum mobile in any system of marine currents.

470. Influence of salts and evaporation.—Let us now proceed another step in the process of explaining and illustrating the effect of the salts of the sea in the system of oceanic circulation. To this end, let us suppose the imaginary ocean of fresh water suddenly to become that which we have, namely, an ocean of salt water which contracts as its temperature is lowered (§ 441) till it reaches 25°.6. Let evaporation now commence in the trade-wind region, as it was supposed to do (§ 468) in the case of the fresh-water seas, and as it actually goes on in nature—and what takes place? Why, a lowering of the sea level, as before. But as the vapour of salt water is fresh, or nearly so, fresh water only is taken up from the ocean; that which remains behind is therefore more salt. Thus, while the level is lowered in the salt sea, the equilibrium is destroyed because of the saltness of the water; for the water that remains after the evaporation takes place is, on account of the solid matter held in solution, specifically heavier than it was before any portion of it was converted into vapour. The vapour is taken from the surface water; the surface water thereby becomes more salt (§ 463), and, under certain conditions, heavier; when it becomes heavier, it sinks; and hence we have, due to the salts of the sea, a vertical circulation, namely, a descent of heavier—because Salter and cooler—water from the surface, and an ascent of water that is lighter—because it is not so salt, or, being as salt, is not so cool (§ 404)—from the depths below. This vapour, then, which is taken up from the evaporating regions (§ 293), is carried by the winds through their channels of circulation, and poured back into the ocean where the regions of precipitation are; and by the regions of precipitation I mean those parts of the ocean, as in the polar basins, where the ocean receives more fresh water in the shape of rain, snow, etc., than it returns to the atmosphere in the shape of vapour. In the precipitating regions, therefore, the level is destroyed, as before explained, by elevation; and in the evaporating regions, by depression; which, as already stated (§ 468), gives rise to a system of surface currents, moving on an inclined plane, from the poles towards the equator. But we are now considering the effects of evaporation and precipitation in giving impulse to the circulation of the ocean where its waters are salt. The fresh water that has been taken from the evaporating regions is deposited upon those of precipitation, which, for illustration merely, we will locate in the north polar basin. Among the sources of supply of fresh water for this basin, we must include not only the precipitation which takes place over the basin itself, but also the amount of fresh water discharged into it by the rivers of the great hydrographical basins of Arctic Europe, Asia, and America. This fresh water, being emptied into the Polar Sea and agitated by the winds, becomes mixed with the salt; but as the agitation of the sea by the winds is supposed to extend to no great depth (§ 468), it is only the upper layer of salt water, and that to a moderate depth, which becomes mixed with the fresh. The specific gravity of this upper layer, therefore, is diminished just as much as the specific gravity of the sea water in the evaporating regions was increased. And thus we have a surface current of saltish water from the poles towards the equator, and an under current of water Salter and heavier from the equator to the poles. This under current of brine supplies, in a great measure, the salt which the upper current, freighted with fresh water from the clouds and rivers, carries back.

471. The under currents going entirely to the salts of sea water.—Thus it is to the salts of the sea that we owe that feature in the system of oceanic circulation which causes an under current to flow from the Mediterranean into the Atlantic (§ 385), and another (§ 377) from the Red Sea into the Indian Ocean. And it is evident, since neither of these seas is salting up, that just as much, or nearly just as much salt as the under current brings out, just so much the upper currents carry in. We now begin to perceive what a powerful impulse is derived from the salts of the sea in giving effective and active circulation to its waters. Hence we infer (§ 461) that the currents of the sea, by reason of its saltness, attain their maxim of volume and velocity. Hence, too, we infer that the transportation of warm water from the equator towards the frozen regions of the poles, and of cold water from the frigid towards the torrid zone, is facilitated; and consequently here, in the dynamical power which the sea derives from its salts, have we not an agent by which climates are mitigated—by which they are softened and rendered much more salubrious than it would be possible for them to be were the waters of the ocean deprived of their property of saltness?

472. A property peculiar to seas of salt water.—This property of saltness imparts to the waters of the ocean another peculiarity, by which the sea is still better adapted for the regulation of climates, and it is this: by evaporating fresh water from the salt in the tropics, the surface water becomes heavier than the average of sea water (§427). This heavy water is also warm water; it sinks, and being a good retainer, but a bad conductor of heat, this warm water is employed in transporting through under currents, heat for the mitigation of climates in far-distant regions. Now this also is a property which a sea of fresh water could not have (§ 430). Let the winds take up their vapour from a sheet of fresh water, and that at the bottom if not disturbed, for there is no change in the specific gravity of that at the surface by which that at the bottom may be brought to the top; but let evaporation go on, though never so gently, from salt water, and the specific gravity of that at the top will soon be so changed as (§ 404) to bring that from the very lowest depths of the sea to the top.

473. Quantity of salt in the sea.—If all the salts of the sea were precipitated and spread out equally over the northern half of this continent, it would, it has been computed, cover the ground one mile deep. What force could move such a mass of matter on the dry land? Yet the machinery of the ocean, of which it forms a part, is so wisety, marvellously, and wonderfully compensated, that the most gentle breeze that plays on its bosom, the tiniest insect that secretes solid matter for its sea-shell, is capable of putting it instantly in motion. Still, when solidified and placed in a heap, all the mechanical contrivances of man, aided by the tremendous forces of all the steam and water power of the world, could not, in centuries of time, move even so much as an inch this matter which the sunbeam, the zephyr, and the infusorial insect keep in perpetual motion and activity.

474. Deductions.—If these inferences as to the influence of the salts upon the currents of the sea be correct, the same cause which produces an under current from the Mediterranean (§ 471), and an under current from the Red Sea into the ocean, should produce an under current from the ocean into the north polar basin; for it may be laid down as a law, that whenever two oceans, or two arms of the sea, or two sheets of water, differing as to saltness, are connected with each other, there are currents between them, viz., a surface current from, and an under current into the sea of lightest water. In every case, the hypothesis with regard to the part performed by the salt, in giving vigour to the system of oceanic circulation, requires that, counter to the surface current of water with less salt, there should be an under current of water with more salt in it. That such is the case with regard both to the Mediterranean and the Red Sea has been amply shown in other parts of this work (§ 471), and abundantly proved by other observers. That, in obedience to this law, there is a constant current setting out of the Arctic Ocean through Davis' and other straits thereabout, which connect it with the Atlantic Ocean, is generally admitted. Lieutenant De Haven, United States Navy, when in command of the American expedition in search of Sir John Franklin, was frozen up with his vessels—the Advance and the Rescue—in mid-channel near Wellington Straits; and during the nine months that he was so frozen, his vessels, like H.B.M. ship Resolute and the Fox (§ 431), each holding its place in the ice, were drifted with it bodily for more than a thousand miles towards the south.

475. Drift of the Resolute.—The drift of these vessels is sufficient, were there no other evidence, to establish the existence of an open sea in the Arctic Ocean; for this drift cannot be accounted for upon any other hypothesis, as a slight examination of the arctic regions on a terrestrial globe, and a careful study of the facts (§ 459), and other phenomena will show.

476. De Haven's drift.—About the middle of September, 1850, being in latitude 74° 40', and in the fair way of Wellington Channel, De Haven found himself, with the Advance, frozen in her tracks, as M'Clintock did the Fox,^[5] in August, 1857, who tried to reach the shore, but he was fast bound, and drifting to the west. De Haven, after having been carried as far as 75° 25', and M'Clintock as far as 75° 30', say within nine hundred miles of the pole, found their northerly course was arrested; then commenced with each that celebrated drift of a thousand miles to the south, and which from December lasted, the one till June, the other till April 25th. These vessels were not drifted through the ice, but with the ice; for in lat. 65° 30', when De Haven was liberated on the 9th of June, he had the same "hummocks," the same snowdrifts, and the same icy landscape which set out with him on December 2nd, when he commenced his drift from the parallel of 75° 25'.^[6]

477. An anti-polynian view.—Now, upon the theory of no open water, and upon the supposition of an ice-covered sea that seals up in winter all the unexplored regions of the north, let us, in imagination, take a survey of that sea just as the anti-polynians, according to their theory, would have it. Let the time of the survey be at the beginning of winter, when De Haven commenced his southwardly drift. From the Advance to the pole—a distance of 900 miles—no water is to be seen: the frost has bridged it all over. From the pole to the distance of 900 miles beyond, and all around, it is one field of thick-ribbed ice. The flat, and tame, and dreary landscape may be relieved here and there, perhaps, by islands, capes, and promontories dotting the surface, but nevertheless it is now at least as cold—being winter—from the pole all around to the parallel of 75°, as it was in early fall when De Haven being near that parallel in Wellington Channel, found his vessel fast bound with the fetters of the frost-king. Wherefore we may suppose that these theorists would admit the whole to be frozen by December. So that, according to the anti-polynian view, we have, measuring from the pole as a centre, a disc of ice more than five thousand miles in circumference, and extending quite down to the shores of arctic America and Asia. Such is the aspect presented by the polar sea without an open water in winter; now, on the 2nd of December—the moment before this remarkable drift commenced—was the entire sheet of ice with which we have supposed the Arctic Ocean to be covered, put in motion, or was that only put in motion which drifted out? By the hypothesis there is no open water in all the circumference of this sea into which the ice might drift. We therefore may well ask the anti-polynians again, How did this drift commence? for commence it did; its movement was out of that sea, and from the pole towards the equator, and so it continued to move for six months at the average rate of 5½miles a day But whence—on what parallel—did it commence? Was the whole disc in motion from the shores of Siberia over across by way of the north pole towards Wellington Channel? If one part of this disc be put in motion, either the whole must be, or there must be somewhere, a split or a rent in it, with open water between. If, during the winter and spring—the coldest period—the edge of this ice-disc nearest Wellington Channel be carried by the currents a thousand miles towards the south, the edge along the Russian shores on the opposite side must have been drifted towards the north a thousand miles also, and so leave an open water behind. Now we simply know there was no such drifting up from the Siberian shores, and the case is put simply to show that in any case the northerly edge of the drifting ice must have come from open water; for if we deny the existence of an open water in that direction, then we must go back and admit that at the beginning of the drift there was ice all the way from Wellington Channel to the North Pole, and thence all the way from the North Pole to the nearest land beyond, which is supposed to be the Siberian shores of the Old World. But, on the other hand, we must also admit the fact—for the Advance, the Rescue, the Fox, and the Resolute are witnesses of it—that a tongue of this ice 1000 miles long was in each of these winters thrust out of the polar basin down through Baffin's Bay into Davis' Straits. These ships came

down upon it. It would be difficult for those who oppose the existence of an open water here in the Arctic Ocean to discover a force there which, during the extreme cold months of the northern night, when the ice is making all the time, could tear from its fastenings and move 5½ miles a day all through the winter and spring a disc of ice seven feet thick^[7] and 1800 geographical miles in diameter. Yet such seem to be the conditions which the absence of open water would require; for, when the Advance was thawed out, there was a thousand miles of ice to the northward of her, and between her and Wellington Channel. This 1000 miles of ice had drifted out of the polar basin during her journey to the south; for when she was liberated there was doubtless a continuous sheet of ice between her in lat. 65°, and Wellington Channel in lat. 75°. This tongue of ice is what the whalemen call the "middle ice" of Baffin's Bay. When the Advance was at Wellington Channel, this thousand miles of ice must, according to the anti-polynians, have been to the north of her; or, according to the other school, it must, as it drifted towards the south, have been forming towards the north at the edge of an open sea (§ 459). And towards the north De Haven saw a water-sky, and towards the north Penny afterwards found an open sea and sailed upon it.

478. The drift explained.—Upon the supposition that the ice which drifts out of the Arctic Ocean in the dead of winter is formed on the edge of an open water not far from the channel through which it drifts, we can account for all the known facts which attended the celebrated drifts of De Haven M'Clintock,^[8] and the Resolute. Upon no other theory can these well-known and well-authenticated facts be reconciled. If there be no open water during this winter drift, which there is reason to believe takes place annually, both the Advance, Fox, and the Resolute indicate that the whole icy covering—the frost-shell of the polar sea in winter—must have drifted bodily far enough, on these three several occasions at least, to set each vessel a thousand miles on her way towards the south. And thus, without bringing in again the long chain of evidence from Chapter IX., the physical necessity of an open sea in the Arctic Ocean is proved,^[9] 479. Thickness of a winter's ice.—On the first of April De Haven measured the ice, and found it seven feet two inches thick. It was formed probably mostly of rain and river water, which, like our own littoral waters (§ 426), protect the Salter and heavier waters below from the cold, for De Haven invariably found the temperature of the water under the ice 28°, which is the temperature that average sea water invariably assumes during the process of congelation (§ 442). Moreover, the specific gravity of the surface water which Rodgers measured in the Arctic Ocean was (§ 427) less than that of average sea water—a fact in confirmation of this conjecture as to the office of rain and river water in the polar sea's. The freezing-point of strong brine is 4°; consequently the freezing-point of water in the sea may vary according to the proportion of salts in it, from 4° all the way up to just below 32°. Thus the salts of the sea impart to its waters an elasticity, as it were, giving a law,—a sort of sliding-scale—both for the thermal dilatation and of congelation, which varies between that of fresh water and the saltest sea water according to the degree of its saltness.

480. Layers of water of different temperature in the Arctic Ocean.—Rodgers tried with his hydrometer and thermometer the waters of the Arctic Ocean at the surface, below, and at the bottom, and as often as he tried he found this arrangement: warm and light water on the top, cool in the middle, "hot and heavy" at the bottom. His experiments were made near Behring's Straits in August, 1855, between the parallels of 71°-2″, and are as per example following:

Date.	Depth.	Temp.	Sp. Grav.	Place
Aug 13	surface	43.8	.0264	Lat.	72° 2'	Long.	174° 37' W.
,,	20 fath.	33.5	.0266	,,	,,	,,	,,
,,	40 fath.[fn 1]	40.5	.0266	,,	,,	,,	,,
Aug. 15	surface	42.5	.0258	,,	71° 21'	,,	175° 22'
,,	12 fath.	39.8	.0264	,,	,,	,,	,,
,,	25 fath.[fn 1]	40.2	.0264	,,	,,	,,	,,

1. Near bottom.

Assuming the surface water which Rodgers used for these experiments to be a fair average of arctic surface waters generally, this table affords data that show the proportion of rain and river water that the Arctic Ocean receives annually. The quantity may be inferred from the fact that average sea water has ten per cent, more salt than attained by Rodgers in the Arctic.

481. The ice-hearing drift from the Arctic like the ordinary drift from the Baltic.—Returning now to the drift of the ice, and the drift of the Advance and her followers, we see that, so far as currents are concerned, we have in the Arctic Ocean a repetition merely of the more familiar phenomenon that is seen in the Baltic, where (§ 383, note) an under current of salt water runs in, and an upper current of brackish water runs out. Then, since there is salt always flowing out of the north polar basin, we infer that there must be salt always flowing into it, else it would either become fresh, or the whole Atlantic Ocean would become more and more briny, and be finally silted up with salt. It might be supposed, were there no evidence to the contrary, that this salt was supplied to the polar seas from the Atlantic around North Cape, and from the Pacific through Behring's Straits, and through no other Channels. But, fortunately, arctic voyagers who have cruised in the direction of Davis' Straits, have confirmed by their observations a law of nature (§ 474), and afforded us proof positive as to the fact of this other source for supplying the polar seas with salt. They tell us of an under current setting from the Atlantic towards the polar basin. They describe huge icebergs, with tops high up in the air, and of course the bases of which extend far down into the depths of the ocean, ripping and tearing their way with terrific force and awful violence through the surface ice or against a surface current, on their way into the polar basin.

482. Icebergs drifting north.—Passed Midshipman S. P. Griffin, who commanded the brig Rescue in the American searching expedition after Sir John Franklin, informs me that, on one occasion, the two vessels were endeavouring, when in Baffin's Bay, to warp up to the northward against a strong surface current, which of course was setting to the south; and that, while so engaged, an iceberg, with its top many feet above the water, came "drifting up" from the south, and passed by them "like a shot." Although they were stemming a surface current against both the berg and themselves, such was the force and velocity of the under current that it carried the berg to the northward faster than the crew could warp the vessel against a surface but counter current. They hooked on to it, and were towed to the north by it. Captain Duncan, master of the English whale-ship Dundee, says, at page 76 of his interesting little narrative:^[10] December 18th (1826). It was awful to behold the immense icebergs working their way to the north-east from us, and not one drop of water to be seen; they were working themselves right through the middle of the ice." And again, at page 92, etc.: February 23rd. Latitude 68° 37' north, longitude about 63° west. The dreadful apprehensions that assailed us yesterday by the near approach of the iceberg were this day most awfully verified. About three p.m. the iceberg came in contact with our floe, and in less than one minute it broke the ice; we were frozen in quite close to the shore; the floe was shivered to pieces for several miles, causing an explosion like an earthquake, or one hundred pieces of heavy ordnance fired at the same moment. The iceberg, with awful but majestic grandeur (in height and dimensions resembling a vast mountain), came almost up to our stern, and every one expected it would have run over the ship The iceberg, as before observed, came up very near to the stern of the ship; the intermediate space between the berg and the vessel was filled with heavy masses of ice, which, though they had been previously broken by the immense weight of the berg, were again formed into a compact body by its pressure. The berg was drifting at the rate of about four knots, and by its force on the mass of ice was pushing the ship before it, as it appeared, to inevitable destruction. Feb. 24th. The iceberg still in sight, but drifting away fast to the north-east. Feb. 25th. The iceberg that so lately threatened our destruction had driven completely out of sight to the north-east from us."

483. Temperature of the under current.—Now, then, whence, unless from the difference of specific gravity due to sea water of different degrees of saltness and temperature, can we derive a motive power in the depths of the sea, with force sufficient to give such tremendous masses of ice such a velocity? What is the temperature of this under current? Rodgers's observations (§ 480) would seem to indicate that at the depth of 150 feet it is not below 40°. Assuming the water of the surface current which runs out with the ice to be all at 28°, as De Haven found it (§ 479), we observe that it is now unreasonable to suppose that the water of the under current, inasmuch as it comes from the south, and therefore from warmer latitudes, is not so cold; and if it be not so cold, its temperature, before it comes out again, must be reduced to 28°, or whatever be the average temperature of the outer but surface current. Dr. Kane found the temperature of the open sea in the Arctic Ocean (§ 429) as high as 36°. Can water in the depths below flow from the mild climate of the temperate zones to the severer climates of the frigid zone without falling below 36°? To what, in the depths of the sea, can a warm current of large volume impart its heat? The temperature of sea water from the tropics in which ice is forming is invariably (§ 442) 28°. Does not the circumstance of De Haven's invariably finding this to be the temperature below the ice on which he drifted tend to confirm the conjecture (§ 479) about the ice and the river water?

484. It comes to the surface.—This under polar current water, then, as it rises to the top, and is brought to the surface by the agitation of the sea in the arctic regions, gives out its surplus heat to warm the atmosphere there till the temperature of this warm under current water is lowered to the requisite degree for going out on the surface. Hence the water-sky of those regions. And the heat that it loses in falling from its normal temperature, be that what it may, till it reaches the temperature of 28°, is so much caloric set free in the polar regions, to temper the air and mitigate the climate there. Now is not this one of those modifications of climate which may be fairly traced back to the effect of the saltness of the sea in giving energy to its circulation? Moreover, if there be a deep sea in the polar basin, which serves as a receptacle for the waters brought into it by this under current, which, because it comes from towards the equatorial regions, comes from a milder climate, and is therefore warmer, we can easily imagine why there might be an open sea in the polar regions—why Lieutenant De Haven, in his instructions (§ 428), was directed to look for it; and why both he and Captain Penny, of one of the English searching vessels, and afterwards Dr. Kane, found it there. And in accounting for this polynia, we see that its existence is not only consistent with the hypothesis with which we set out, touching a perfect system of oceanic circulation, but that it may be ascribed, in a great degree at least, if not wholly, to the effect produced by the salts of the sea upon the mobility and circulation of its waters. Here, then, is an office which the sea performs in the economy of the universe by virture of its saltness, and which it could not perform were its waters altogether fresh. And thus philosophers have a clew placed in their hands which will probably guide them to one of the many hidden treasures that are embraced in the true answer to the question, "Why is the sea salt?"

485. Sea shells—their influence upon currents.—We find in sea water other matter (§ 48) besides common salt. Lime is dissolved by the rains and the rivers, and emptied in vast quantities into the ocean. Out of it, coral islands and coral reefs of great extent—marl-beds, shell-banks, and infusorial deposits of enormous magnitude, have been constructed by the inhabitants of the deep. These creatures are endowed with the power of secreting, apparently for their own purposes only, solid matter, which the waters of the sea hold in solution. But this power was given to them that they also might fulfil the part assigned them in the economy of the universe. For to them, probably, has been allotted the important office of assisting to give circulation to the ocean, of helping to regulate the climates of the earth, and of preserving the purity of the sea. The better to comprehend how such creatures may influence currents and climates, let us again suppose the ocean to be perfectly at rest—that throughout, it is in a state of complete equilibrium—that, with the exception of those tenants of the deep which have the power of extracting from it the solid matter held in solution, there is no agent in nature capable of disturbing that equilibrium —and that all these fish, etc., have suspended their secretions, in order that this state of a perfect aqueous equilibrium and repose throughout the sea might be attained. In this state of things—the waters of the sea being in perfect equilibrium—a single mollusk or coralline, we will suppose, commences his secretions, and abstracts from the sea water (§ 465) solid matter for his cell. In that act this animal has destroyed the equilibrium of the whole ocean, for the specific gravity of that portion of water from which this solid matter has been abstracted is altered. Having lost a portion of its solid contents, it has become specifically lighter than it was before; it must, therefore, give place to the pressure which the heavier water exerts to push it aside and to occupy its place, and it must consequently travel about and mingle with the waters of the other parts of the ocean until its proportion of solid matter is returned to it, and until it attains the exact degree of specific gravity due to sea water generally.

486. Solid matter secreted by them.—How much solid matter does the whole host of marine plants and animals abstract from sea water daily? Is it a thousand pounds, or a thousand millions of tons? No one can say. But, whatever be its weight, it is so much of the power of gravity applied to the dynamical forces of the ocean. And this power is derived from the salts of the sea, through the agency of sea-shells and other marine animals, that of themselves scarcely possess the power of locomotion. Yet they have power to put the whole sea in motion, from the equator to the poles, and from top to bottom. But we have yet to inquire how far may currents be due to the derangement of equilibrium arising from the change of specific gravity caused by the secretions of the myriads of marine animals that are continually at work in various parts of the ocean. These little creatures abstract from sea water solid matter enough to build continents of. And, also, we have to remember as to the extent to which equilibrium in the-sea is disturbed by the salts which evaporation leaves behind. Thus, when we consider the salts of the sea in one point of view, we see the winds and the marine animals operating upon the waters, and, in certain parts of the ocean, developing by their action upon the solid contents of the same those very principles of antagonistic forces which hold the earth in its orbit, and preserve the harmonies of the universe.

487. Dynamical force derived from.—From another point of view, we see the sea-breeze and the sea-shell, in performing their appointed offices, so acting as to give rise to a reciprocating motion in the waters; and thus they impart to the ocean dynamical forces also for its circulation. The sea-breeze plays upon the surface; it converts only fresh water into vapour, and leaves the solid matter behind. The surface water thus becomes specifically heavier, and sinks. On the other hand, the little marine architect below, as he works upon his coral edifice at the bottom, abstracts from the water there a portion of its solid contents; it therefore becomes specifically lighter, and up it goes, ascending to the top with increased velocity, to take the place of the descending column, which, by the action of the winds, has been sent down loaded with fresh food and materials for the busy little mason in the depths below. Seeing, then, that the inhabitants of the sea, with their powers of secretion, are competent to exercise at least some degree of influence in disturbing equilibrium, are not these creatures entitled to be regarded as agents which have their offices to perform in the system of oceanic circulation, and do they not belong to its physical geography? Their influences upon the economy of the sea are like those outstanding quantities which the astronomer finds in the periods of heavenly bodies. He calls them perturbations; for short, or even during considerable intervals, their effects may be inappreciable; for they are pendulums that require ages for a single vibration; but unless there was a balance provided somewhere, they would, during the progress of time, accumulate their small perturbations so as to produce disorder, and finally cause the destruction of worlds. So, too, with the salts of the sea, and those little microscopic inhabitants of its waters. They take care of its outstanding quantities of solid matter, and by their influence preserve harmony in the ocean. It is immaterial how great or how small that influence may be supposed to be; for, be it great or small, it is cumulative; and we therefore may rest assured it is not a chance influence, but it is an influence exercised by design, and according to the commandment of Him whose "voice the winds and the sea obey." Thus God speaks through sea-shells to the ocean.

488. Their physical relations.—It may therefore be supposed that the arrangements in the economy of nature are such as to require that the various kinds of marine animals, whose secretions are calculated to alter the specific gravity- of sea water, to destroy its equilibrium, to beget currents in the ocean, and to control its circulation, should be distributed according to order. Upon this supposition—the like of which Nature warrants throughout her whole domain—we may conceive how the marine animals of which we have been speaking may impress other features upon the physical relations of the sea by assisting also to regulate climates, and to adjust the temperature of certain latitudes. For instance, let us suppose the waters in a certain part of the torrid zone to be 90°, but, by reason of the fresh water which has been taken from them in a state of vapour, and consequently by reason of the proportionate increase of salts, these waters are heavier than waters that may be cooler, but not so salt (§ 105). This being the case, the tendency would be for this warm, but salt and heavy water to flow off as an under current towards the polar or some other regions of lighter water; but these creatures take from it a portion of these salts for their own purposes, and so make it light enough to flow off on the surface instead of the bottom—it then goes polarward, dispensing warmth and moisture as it goes; and so climate may be influenced. Moreover, if the sea were not salt, there would be no coral islands to beautify its landscapes and give variety to its features; sea-shells and marine insects could not operate upon the specific gravity of its waters, nor assist in giving diversity to its climates; neither could evaporation give dynamical force to its circulation; its waters, ceasing to contract as their temperature falls below 39°, would give but little impulse to its currents, and impart no motion (§ 404) to its waters in the depths below: thus its circulation would be torpid, and its bosom lack animation. In some other parts of the ocean, instead of there being organic life capable of changing, by animal or vegetable secretions, the specific gravity of the supposed salt and heavy and hot water at 90°, there may be none such, as in a "Desolate Region." This water then may go off as an under-current freighted with heat to temper some hyperborean region or to soften some extra-tropical climate, for we know that such is among the effects of marine currents. At starting, it might have been, if you please, so loaded with solid matter that, though its temperature were 90°, yet, by reason of the quantity of such matter held in solution, its specific gravity might have been greater even than that of extra-tropical sea water generally at 28°. Notwithstanding this, after travelling below to certain latitudes, it may be brought into contact by the way, with those kinds and quantities of marine organisms that shall abstract solid matter enough to reduce its specific gravity, and, instead of leaving it greater than common sea water at 28°, make it less than common sea water at 40°; consequently, in such a case, this warm sea water, when it comes to the cold latitudes, would be brought to the surface through the instrumentality of shell-fish, and various other tribes that dwell far down in the depths of the ocean. Thus we perceive that these creatures, though they are regarded as beings so low in the scale of creation, may nevertheless be regarded as agents of much importance in the terrestrial economy; for we now comprehend how they are capable of spreading over certain parts of the ocean those benign mantles of warmth which temper the winds, and modify, more or less, all the marine climates of the earth.

489. The regulators of the sea.—The makers of nice astronomical instruments, when they have put the different parts of their machinery together, and set it to work, find, as in the chronometer, for instance, that it is subject in its performance to many irregularities and imperfections; that in one state of things there is expansion, and in another state contraction among cogs, springs, and wheels, with an increase or diminution of rate. This defect the makers have sought to overcome; and with a beautiful display of ingenuity, they have attached to the works of the instrument a contrivance which has had the effect of correcting these irregularities by counteracting the tendency of the instrument to change its performance with the changing influences of temperature. This contrivance is called a compensation; and a chronometer or clock that is well regulated and properly compensated will perform its office with certainty, and preserve its rate under all the vicissitudes of heat and cold to which it may be exposed. In the clock-work of the ocean and the machinery of the universe, order and regularity are maintained by a system of compensations. A celestial body, as it revolves around its sun, flies off under the influence of centrifugal force; but immediately the forces of compensation begin to act, the planet is brought back to its elliptical path, and held in the orbit for which its mass, its motions, and its distances were adjusted. Its compensation is perfect. So, too, with the salts and shells of the sea in the machinery of the ocean; from them are derived principles of compensation the most perfect; through their agency the undue effects of heat and cold, of storm and rain, in disturbing the equilibrium and producing thereby currents in the sea, are compensated, regulated, and controlled. The dews, the rains, and the rivers are continually dissolving certain minerals of the earth, and carrying them off to the sea. This is an accumulative process; and if it were not compensated, the sea would finally become, as the Dead Sea is, saturated with salt, and therefore unsuitable for the habitation of many fish of the sea. The sea-shells and marine insects afford the required compensation. They are the conservators of the ocean. As the salts are emptied into the sea, these creatures secrete them again and pile them up in solid masses, to serve as the bases of islands and continents, to be in the process of ages upheaved into dry land, and then again dissolved by the dews and rains, and washed by the rivers away into the sea again.

490. Whence does the sea derive its salts?—The question as to whence the salts of the sea were originally derived, of course has not escaped the attention of philosophers. I once thought with Darwin and those other philosophers who hold that the sea derived its salts originally from the washings of the rains and rivers. I now question that opinion for, in the course of the researches connected with the "Wind and Current Charts," I have found evidence, from the sea and in the Bible, which seems to cast doubt upon it. The account given in the first chapter of Genesis, and that contained in the hieroglyphics which are traced by the hand of Nature on the geological column as to %he order of creation, are marvellously accordant. The Christian man of science regards them both as true; and he never overlooks the fact that, while they differ in the mode and manner as well as in the things they teach, yet they never conflict; and they contain no evidence going to show that the sea was ever fresh; on the contrary, they both afford circumstantial evidence sufficient for the belief that the sea was salt as far back as the morning of creation, or at least as the evening and the morning of the day when the dry land appeared. That the rains and the rivers do dissolve salts of various kinds from the rocks and soil, and empty them into the sea, there is no doubt. These salts cannot be evaporated, we know; and we also know that many of the lakes, as the Dead Sea, which receive rivers and have no outlet, are salt. Hence the inference by some philosophers that these inland water-basins received their salts wholly from the washings of the soil; and consequently the conjecture arose that the great sea derived its salts from the same source and by the same process. But, and per contra, though these solid ingredients cannot be taken out of the sea by evaporation, they can be extracted by other processes. We know that the insects of the sea do take out a portion of them, and that the salt ponds and arms which, from time to time in the geological calendar, have been separated from the sea, afford an escape by which the quantity of chloride of sodium in its waters—the most abundant of its solid ingredients —is regulated. The insects of the sea cannot build their structures of this salt, for it would dissolve again, and as fast as they could separate it. But here the ever-ready atmosphere comes into play, and assists the insects in regulating the salts. It cannot take them up from the sea, it is true, but it can take the sea away from them: for it pumps up the water from these pools that have been barred off, transfers it to the clouds, and they deliver it back to the sea as fresh water; leaving the salts it contained in a solid state behind. These are operations that have been going on for ages; proof that they are still going on is continually before our eyes; for the "hard water" of our fountains, the marl-banks of the valleys, the salt-beds of the plains, Albion's chalky cliffs, and the coral islands of the sea, are monuments in attestation. These masses of solid matter have been secreted from the sea waters; they express the ability of these creatures to prevent the accumulation of salts in the sea.

491. Their antiquity.—There is no proof, nor is there any reason for the belief, that the sea is growing salter or fresher. Hence we infer that the operations of addition and extraction are reciprocal and equal; that the effect of rains and rivers in washing down is compensated by the processes of evaporation and secretion in taking out. If the sea derived its salts originally from the rivers, the geological records of the past would show that river beds were scored out in the crust of our planet before the sea had deposited any of its fossil shells and infusorial remains upon it. If, therefore, we admit the Darwin theory, we must also admit that there was a period when the sea was without salt, and consequently without shells or animals either of the silicious or calcareous kind. If ever there was such a time, it must have been when the rivers were collecting and pouring in the salts which now make the brine of the ocean. But while the palaeontological records of the earth, on one hand, afford no evidence of any such fresh- water period, the Mosaic account is far from being negative with its testimony on the other. According to it, we infer that the sea was salt as early, at least, as the fifth day, for it was on that day of creation that the waters were commanded to "bring forth abundantly the moving creature that hath life." It is in obedience to that command that the sea now teems with organisms; and it is marvellous how abundantly the obedient waters do bring forth, and how wonderful for variety as well as multitude their progeny is. All who pause to look are astonished to see how the prolific ocean teems and swarms with life. The moving creatures in the sea constitute in their myriads of multitudes one of the "wonders of the deep."

492. Insects of the sea—their abundance.—It is the custom of Captain Foster, of the American ship Garrick, who is one of my most patient of observers, to amuse himself by making drawings in his abstract log of the curious animalculae which. with the microscope, lie finds in the surface water alongside; and though he has been following the sea for many years, he never fails to express his wonder and amazement at the immense numbers of living creatures that the microscope reveals to him in sea water. Hitherto his examinations related only to the surface waters, but in the log now before me he went into the depths, and he was more amazed than ever to see how abundantly the waters even there bring forth. "January 28th, 1855.—In examining animalculæ in sea water, I have," says he, "heretofore used surface water. This afternoon, after pumping for some time from the stern pump seven feet below the surface, I examined the water, and was surprised to find that the fluid was literally alive with animated matter, embracing beautiful varieties." Of some he says, "Numerous heads, purple, red, and variegated." There is wonderful meaning in that word abundantly, as it stands recorded in that Book, and as it is even at this day repeated by the great waters, a striking instance of which has been furnished by Piazzi Smyth, the Astronomer Royal of Edinburgh, during his voyage in 1856, on an astronomical expedition to Teneriffe. On that occasion he fell in with the annual harvest of medusæ (§ 160) that are sent by the Gulf Stream to feed the whales. His description of them (§ 161) has already been quoted. According to the computation made by him, it appears that each one of these sea-nettles, as they are sometimes called, had in his stomachs not less than five or six millions of flinty shells, the materials for which their builders had collected from the silicious matter which the rains washed out from the mountains, and which the rivers bring down to the sea. The medusæ have the power of sucking in the sea water slowly, drop by drop, at one end, and of ejecting it at the other. From this they derive both food and locomotion; for in the passage of the water, they strain it, and collect the little diatomes. Imagine, then, how many drops of water in the sea, which, though loaded with diatomes, never pass through the stomach of the medusæ. Imagine how many the whale must gulp down with every mouthful of medusæ. Imagine how deep and thickly the bottom of the sea must, during the process of ages, have become covered with the flinty shells of these little creatures. And then recollect the command which was given to the waters of the sea on the fifth day, and we may form some idea of how literally they have obeyed this order, bringing forth most abundantly even now the moving creature that hath life, and doing it in obedience to that command.

493. Ditto, calcareous in the Pacific, silicious in the Atlantic.—In the waters of the Pacific Ocean, the calcareous matter seems to be in excess, for the microscopic shells there, as well as the conch and the coral, are built mostly of lime. In contemplating this round of compensations, the question may be asked, Where is the agent that regulates the supply of solid materials for the insects of the sea to build their edifices of? Answer: The rivers. They bring down, and pour into the sea continually, the pabulum which those organisms require. This amount again depends upon the quantity and power of the rains to wash out from the solid rock; and the rains depend upon the amount of vapour that the sea delivers to the winds, which, as Chapman's observations show, depends directly upon the salts of the sea.

494. The records of the sea and of revelation agree.—So far the two records agree, and the evidence is clear that the sea was salt when it received its command. Do they afford any testimony as to its condition previously? Let us examine:—On the second day of creation the waters were gathered together unto one place, and the dry land appeared. Before that period, therefore, there were no rivers, and consequently no washings of brine by mists, nor dew, nor rains for the valleys among the hills. The water covered the earth. This is the account of revelation; and the account which Nature has written, in her own peculiar characters, on the mountain and in the jolain, on the rock and in the sea, as to the early condition of our planet, indicates the same. The inscriptions on the geological column tell that there was a period when the solid parts of the earth's crust which now stand high in the air were covered by water. The geological evidence that it was so, with perhaps the exception of a solitary mountain peak here and there, is conclusive; and when we come to examine the fossil remains that are buried on the mountains and scattered over the plains, we have as much reason to say that the sea was salt when it covered or nearly covered the earth, as the naturalist, when he sees a skull or bone whitening on the wayside, has to say that it was once covered with flesh. Therefore we have reason for the conjecture that the sea was salt "in the beginning," when "the waters under heaven were gathered together under one place," and the dry land first appeared; for, go back as far as we may in the dim records which young Nature has left inscribed upon the geological column of her early processes, and there we find the fossil shell and the remains of marine organisms to inform us that when the foundations of our mountains were laid with granite, and immediately succeeding that remote period when the primary formations were completed, the sea was, as it is now, salt; for had it not been salt, whence could those creeping things which fashioned the sea-shells that cover the tops of the Andes, or those madrepores that strew the earth with solid matter that has been secreted from briny waters, or those infusorial deposits which astound the geologist with their magnitude and extent, or those fossil remains of the sea which have astonished, puzzled, and bewildered man in all ages—whence, had not the sea been salt when its metes and bounds were set, could these creatures have obtained solid matter for their edifices and structures? Much of that part of the earth's crust which man stirs up in cultivation, and which yields him bread, has been made fruitful by these "salts," which all manner of marine insects, aqueous organisms, and sea-shells have secreted from the ocean. Much of this portion of our planet has been filtered through the sea, and its insects and creeping things are doing now precisely what they were set about when the dry land appeared, namely, preserving the purity of the ocean, and regulating it in the due performance of its great offices. As fast as the rains dissolve the salts of the earth, and send them down through the rivers to the sea, these faithful and everlasting agents of the Creator elaborate them into pearls, shells, corals, and precious things; and so, while they are preserving the sea, they are also embellishing the land by imparting new adaptations to its soil, fresh beauty and variety to its landscapes. Whence came the salts of the sea originally is a question which perhaps never will be settled satisfactorily to every philosophic mind, but it is sufficient for the Christian philosopher to recollect that the salts of the sea, like its waters and the granite of the hills, are composed of substances which, when reduced to their simple state, are found for the most part to be mere gaseous or volatile matter of some kind or other. Thus we say that granite is generally composed of feldspar, mica, and quartz, yet these three minerals are made of substances more or less volatile in combination with oxygen gas. Iron, of which there is merely a trace, is the only ingredient which, in its uncombined and simple state, is not gaseous or volatile. Now, was the feldspar of the granite originally formed in one heap, the mica in another, and the quartz in a third, and then the three brought together by some mighty power, and welded into the granite rock for the everlasting hills to stand upon? or were they, as they were formed of the chaotic matter, made into rock? Sea water is composed of oxygen and hydrogen, and its salts, like the granite, also consist of gases and volatile metals. But whether the constituents of sea water, like those of the primitive rocks, were brought together in the original process of formation, and united in combination as we now find them in the ocean, or whether the sea was fresh "in the beginning," and became salt by some subsequent process, is not material to our present purpose. Some geologists suppose that in the Chalk period, when the ammonites, with their huge chambered shells, lived in the sea, the carbonaceous material required by these creatures for their habitations must have been more abundant in its waters than it now is; but, though the constituents of sea water may have varied as to proportions, they probably were never, at least "since its waters commenced to bring forth," widely different from what they now are. It is true, the strange cuttle-fish, with its shell twelve feet in circumference, is no longer found alive in the sea: it died out with the Chalk period; but then its companion, the tiny nautilus, remains to tell us that even in that remote period the proportion of salt in sea water was not unsuited to its health, for it and the coral insect have lived through all the changes that our planet has undergone since the sea was inhabited, and they tell us that its waters were salt as far back, at least, as their records extend, for they now build their edifices and make their habitations of the same materials, collected in the same way that they did then, and, had the sea been fresh in the interim, they too would have perished, and their family would have become extinct, like that of the great ammonite, which perhaps ceased to find the climates of the sea, not the proportion of its salts, suited to its well-being.

495. Cubic miles of sea salt.—Did any one who maintains that the salts of the sea were originally washed down into it by—the rivers and the rains ever take the trouble to compute the quantity of solid matter that the sea holds in solution as salts? Taking the average depth of the ocean at three miles, and its average saltness at 3½ per cent., it appears that there is salt enough in the sea to cover to the thickness of one mile an area of several millions of square miles. These millions of cubic miles of crystal salt have not made the sea any fuller. All this solid matter has been received into the interstices of sea water without swelling the mass; for chemists tell us that water is not increased in volume by the salt it dissolves. Here we have therefore displayed before us an economy of space calculated to surprise even the learned author himself of the "Plurality of Worlds."

496. The saltness of water retards evaporation.—There has been another question raised which bears upon what has already been said concerning the offices which, in the sublime system of terrestrial arrangements, have been assigned to the salts of the sea. On the 20th of January, 1855, Professor Chapman, of the University College, Toronto, communicated to the Canadian Institute a paper on the "Object of the salt condition of the sea," which, he maintains, is "mainly intended to regulate evaporation." To establish this hypothesis, he shows by a simple but carefully conducted set of experiments that, the Salter the water, the slower the evaporation from it; and that the evaporation which takes place in 24 hours from water about as salt as the average of sea water is 0.54 per cent, less in quantity than from fresh water. "This suggestion and these experiments give additional interest to our investigations into the manifold and marvelloiis offices which, in the economy of our planet, have been assigned by the Creator to the salts of the sea. It is difficult to say what, in the Divine arrangement, was the main object of making the sea salt and not fresh. Whether it was to assist in the regulation of climates, or in the circulation of the ocean, or in re-adapting the earth for new conditions by transferring solid portions of its crust from one part to another, and giving employment to the corallines and insects of the sea in collecting this solid matter into new forms, and presenting it under different climates and conditions, or whether the main object was, as the distinguished professor suggests, to regulate evaporation, it is not necessary now or here to discuss. I think we may regard all the objects of the salts of the sea as main objects. But we see in the professor's experiments the dawn of more new beauties, and the appearance of other exquisite compensations, which, in studying the 'wonders of the deep,' we have so often paused to contemplate and admire:—As the trade- wind region feeds the air with the vapour of fresh water, the process of evaporation from the sea is checked, for the water-which remains, being salter, parts with its vapour less readily; and thus, by the salts of the sea, floods may be prevented. But again, if the evaporating surface were to grow Salter and Salter, whence would the winds derive vapour duly to replenish the earth with showers? for the Salter the surface, the more scanty the evaporation. Here is compensation, again, the most exquisite; and we perceive how, by reason of the salts of the sea, drought and flood, if not prevented, may be, and probably are, regulated and controlled; for that compensation which assists to regulate the amount of evaporation is surely concerned in adjusting also the quantity of rain. Were the salts of the sea lighter instead of heavier than the water, they would, as they feed the winds with moisture for the cloud and the rain, remain at its surface, and become more niggardly in their supplies, and finally the winds would howl over the salt-covered sea in very emptiness, and, instead of cool and refreshing sea-breezes to fan the invalid and nourish the plants, we should have the gentle trade-winds coming from the sea in fitful blasts of parched, and thirsty, and blighting air. But sea salts, with their manifold and marvellous adaptations, come in here as a counterpoise, and, as the waters attain a certain degree of saltness, they become too heavy to remain longer in contact with the thirsty trade-winds, and are carried down, because of their weight, into the depths of the ocean; and thus the winds are dieted with, vapour in due and wholesome quantities."—Maury's Sailing Directions, 7th ed., p. 862.

497. The harmonies of the ocean.—Since the offices which, in the operations of the physical machinery of the earth, have been assigned to the salts of the sea, are obviously so important and manifold, it is fair for us to presume that, as for the firmament above, so with that below, the principles of conservation were in the beginning provided for each alike, for the world in the sky and the drop in the sea; that when the Creator gathered the waters together into one place, and pronounced his handiwork "GOOD," some check or regulator had already been provided for the one as well as the other—checks which should keep the sea up to its office, preventing it from growing, in the process of ages, either larger or smaller, fresher or salter. As we go down into the depths of the sea, we find that we are just beginning to penetrate the chambers of its hidden things, and to comprehend its wonders. The heart of man was never rightly attuned to the music of the spheres until he was permitted to stand with his eye at the telescope, and then, for the first time, the song of the morning stars burst upon him in all its glory. And so it is with the harmonies of old Ocean when contemplated through the microscope; then every drop of water in the sea is discovered to be in tune with the hosts of heaven, for each stands forth a peopled world.

498. The microscope and the telescope.—Catching, as we contemplate the hosts of heaven through the telescope and the moving-creatures of the sea through the microscope, the spirit of Chalmers, and borrowing his fine imagery, let us draw a contrast between the glories of the heavens and the wonders of the insect world of earth and sea, as to the mind of a devout philosopher they are presented through these instruments: "One leads him to see a world in every atom, the other a system for every star. One shows him that this vast globe, with its mighty nations and multitudinous inhabitants, is but a grain of sand in the immensity of space; the other, that every particle of clay that lies buried in the depths of the sea has been a living habitation, containing within it the workshops of a busy population. One tells him of the insignificance of the world we inhabit; the other redeems it from that insignificance by showing in the leaves of the forest, in the flowers of the field, and in every drop of water in the sea, worlds as numberless as the sands on its shores, all teeming with life, and as radiant with glories as the firmament of heaven. One suggests that, beyond and above all that is visible to man, their are fields of creation which sweep immeasurably along, and carry to the remotest regions of space the impress of the Almighty hand; the other reminds us that, within and beneath all that minuteness which the eye of man has been able to explore, there may be a region of invisibles, and that, could we draw aside the veil that hides it from our senses, we should behold a theatre of as many worlds as astronomy has unfolded—a universe within the compass, of a point so small as to elude the highest power of the microscope, but where the wonder-working finger of the Almighty finds room for the exercise of his attributes—where He can raise another mechanism of worlds, filling and animating them all with the evidences of his glory." When we lay down the microscope, and study the organisms of the sea by the light of reason, we find grounds for the belief that the sea was made salt in the beginning,for the marine fossils that are found nearest the foundation of the geological column remind us that in their day the sea was salt; and then, when we take up the microscope again to study the foraminiferse, the diatomes, and corallines, and examine the structure of the most ancient inhabitants of the deep, comparing their physiology with that of their kindred in the fossil state, we are left to conjecture no longer, but are furnished with evidence and proof the most convincing and complete that the sea is salt from a physical necessity.

499. Sea-shells and animalculæ in a new light.—Thus beholding sea-shells and animalcule, may we not now cease to regard them as beings which have little or nothing to do in maintaining the harmonies of creation? On the contrary, do we not see in them the principles of the most admirable compensation in the system of oceanic circulation? We may even regard them as regulators, to some extent, of climates in parts of the earth far removed from their presence. There is something suggestive, both of the grand and the beautiful, in the idea that, while the insects of the sea are building up their coral islands in the perpetual summer of the tropics, they are also engaged in dispensing warmth to distant parts of the earth, and in mitigating the severe cold of the polar winter. Surely an hypothesis which, being followed out, suggests so much design, such perfect order and arrangement, and so many beauties for contemplation and admiration as does this, which, for want of a better, I have ventured to offer with regard to the solid matter of the sea water, its salts and its shells—surely, I say, such an hypothesis, though it be not based entirely on the results of actual observation, cannot be regarded as wholly vain or as altogether profitless.

1. Melloni has shown that the power of salt water to transmit heat is very much greater than that of fresh.
2. The great American lakes afford, it may be supposed, a considerable portion of the vapour which goes to make rain for the hydrographic basin in which they are. Visiting the Lake country in 1858, I was struck with the fact that so few trees bore the marks of lightning. The rule appeared to be, the nearer the lakes, the more rare was it for one of these ornaments of the forest to have been defaced by lightning; and, on inquiry from the Lake Board of Underwriters, I was informed that among the records of lake disasters there was not a single instance of a vessel having been struck by lightning on the North American lakes!
3. Youman's Chemistry.
4. 39° 5.
5. A screw yacht of 177 tons.
6. De Haven was frozen in lat. 74° 40', long. 92° 55'; was carried up to 75° 25' N., and thence down to 66° 15' N., 58° 35' W., when he was liberated. The Fox was frozen in 75° 30' N., 64° W.; was carried west to 69° in the same latitude, and thence down to 63° 50' N., and 57° W., when she was liberated. The Resolute was abandoned in lat. 74° 40', long. 101° 20', and was picked up afloat of Cape Mercy in 65° N.
7. De Haven found the ice upon which his vessel was brought out 7 feet 2 inches thick.
8. In the Fox, 1857-1858.
9. The Fox accomplished another of those remarkable drifts which can be explained upon no other hypothesis but that of an open water in the Arctic Ocean, and that, too, not far from the entrance into it of some of the channels which connect it with Baffin's Bay on the polar side of 75°. The Fox was attempting to pass from Melville Bay over to Lancaster Sound.in August, 1857, When, on the th day of that month she fell in with ice, in which she was finally frozen up, and remained so for 242 days, during which time she was drifted to the southward 1194 miles, which gives an average rate of five miles a day. "This drift, the drift of the Resolute, of the Advance, and Rescue, each upwards of a thousand miles—appears to indicate that a similar drift takes place every year. They show the existence of a polynia, and indicate that the open sea is to be sought for at no greater distance from Kennedy's Channel on the one hand, and Maury's on the other. This conclusion is reached by a process of reasoning of this sort: "When each one of these vessels was released from her cold fetters, there was doubtless behind her, and between her place of release and her place of original imprisonment, an uninterrupted reach of a thousand miles covered with ice; which ice, during the fall, the winter, and early spring, drifted out of the Arctic Ocean. Now we have the choice of two suppositions, and of only two, in explanation of this phenomenon, and they are: Either that the great body of all the winter-formed ice of the Arctic Ocean must have drifted in an unbroken mass over towards Baffin's Bay; for these vessels were brought out upon a tongue of ice thrust through that bay down into Davis' Straits; or that this tongue must have been separated from the main mass, leaving behind that from which it had been severed. "By the latter supposition all the known facts of the case may be reconciled; by the former not one. "If we suppose this drifting field of ice to be formed upon the very verge of an open sea, and to drift to the south as fast as it is formed, then the whole phenomenon becomes one of easy solution. At any rate, we are now possessed of a physical fact which probably would have returned Captain Crozier and his companions to us all safe and sound had they been aware of its existence; and that fact is in this oft-occurring, if not regular and annual, southward drift of ice from the Arctic Ocean down through Baffin's Bay into Davis' Strait. Captain Franklin, being ignorant of it, placed his vessels out of its reach on the south, where he was frozen in and died, and where Captain Crozier, his successor, remained imprisoned for eighteen months and then abandoned his ships: their drift in the mean time, and for obvious reasons, being almost, if not quite insensible, except as influenced by the summer thaw and 'winter wedgings.' Now if those vessels, with their scurvy-riddled, frost-worn and disabled crews, could have been placed farther to the north, as in Barrow's Strait, or in the fair way of any of those channels connecting with it from the northward and westward, or with Baffin's Bay, the probabilities are that this regularly occurring winter drift would have brought them down safely into milder climates, and into the glad waters of the Atlantic Ocean, as it did those four other vessels. "The frequent, if not the regular annual occurrence of this drift down through Baffin's Bay is a fact which will be considered by all future arctic explorers as one of great importance, for it affords the means of escaping from the Arctic Ocean in the severest winter."—Transactions of the American Geo. Society, 1860.
10. Arctic Regions; Voyage to Davis' Strait, by Dorea Duncan, Master of the ship Dundee, 1826, 1827.