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pipe. "From the banks of Newfoundland | but the medusæ, or sea-nettles, its princito the shores of Europe is the basement pal food, are bred in the warm seas of -the hot-air chamber in which this pipe the south. From the Gulf of Mexico, is flared out, so as to present a large cool- the great nursery of these medusa, the ing surface. Here the circulation of the Gulf Stream carries them in shoals for atmosphere is arranged by nature; and it thousands of miles, to feed the starving is such, that the warmth thus conveyed whale in its own gelid waters.* into this warm air-chamber of mid-ocean is taken up by the genial west winds, and dispersed, in the most benign manner, throughout Great Britain and the west of Europe." In support of these views, our author informs us, that the maximum temperature of the Gulf Stream is 86°, or about 90 above the ocean temperature; that it loses 2 by an increase of 10° of latitude; and that, after running 3000 miles northward, it still preserves, in winter, the heat of summer, and in this state crosses 40° of north latitude. Here it overflows its liquid banks, and spreads itself for thousands of square leagues, over the cold waters around-" covering the ocean with a mantle of warmth," and carrying with it a mild and moist atmosphere, which mitigates in Europe the rigors of winter, and extends its genial influence even into the polar basin of Spitzbergen. Ireland, says Lieutenant Maury, is thus made the "Emerald Isle of the Sea," and the shores of Britain clothed with evergreen robes, while, in the same latitude, Labrador is fast bound

in ice.

But while the Gulf Stream is thus generous to the north of Europe, its beneficial influences are felt in the south. The cold

waters from the north descend towards the Equator, and moderate the burning climates in the Caribbean Sea, and round the Gulf of Mexico. These cold currents bring along with them the fish of the northern seas, and thus give the inhabitants of the south a supply of fish far superior to that which is bred in their heated waters. The fish of warm climates, though beautiful and gorgeous in their colors, are soft and unfit for table; while in the current of cold water in the Pacific, called Humboldt's Current, which sweeps the shores of Chili, Peru, and Columbia, and reaches even the Gallipagos Islands, under the Line, there is throughout the whole of that distance an abundant supply of excellent fish. These cold and warm currents, therefore, are the great highways through which fishes travel from one region to another. The whale, it is well known, can not exist in warm waters;

One of the most remarkable properties of the Gulf Stream, is the influence which it exercises over the meteorology of the ocean. The most furious gales sweep along with it; and it is doubtless the cause of the fogs of Newfoundland, which are so dangerous to navigation in winter. Many gales have been traced to the Gulf Stream from their origin; and gales which rise on the coast of Africa, as far south as 10° or 150 of N. latitude, have been known to join it, and to travel with it, turning around to recross the Atlantic for the shores of Europe. Gales thus attracted to the Gulf Stream are the most terrific on the ocean, and their course is marked by the most serious disasters. In 1854 upwards of seventy vessels were wrecked, dismasted, or damaged, in one of these tornadoes; the current of the stream running in one direction, and the wind blowing in another, so as to create a sea of the most frightful kind. storms are said to be, for the most part, rotatory ones, such as have been described by Piddington, Redfield, and Reid; but it is a question still to be settled, why these storms are attracted towards the Gulf Stream, and follow it in its course.

These

We have thus seen, under the guidance of our distinguished author, how the equatorial winds convey the heat over the waters of the tropics in the Northern Hemisphere, raising the temperature of the Atlantic, warming even the Arctic Seas, and therefore necessarily improving, to some extent, the climate of the west of Europe. We can not, however, agree with Lieutenant Maury in regarding the Gulf Stream as the sole, or even the principal, cause of the temperature which characterizes the warm meridian that passes through the west of Europe. In a former article,f relative to the distribu

* Off the coast of Florida, shoals of young medusæ have been seen, thickly covering the sea for many leagues. A sea captain, bound to England, was five or six days in sailing through them. On his return, sixty days afterwards, he encountered the same shoal, and was three or four days in passing through it.

See Review of Humboldt's "Central Asia," in vol. v., pp. 491-503.

and the spider's line glitters with the varied tints of the sun. The silence of death is broken only by the hum of life. Over this trance of nature a change speedily supervenes. The distant forest announces the approach of the tempestthe oak and the pine are crushed by its power; the proudest monuments of human skill are leveled with the dust; and the slumbering ocean, chafed into fury, dashes the war-ship against its cliffs, or sinks it beneath its waves. Resting upon the stream, and lake, and sea, the porous air sucks up their waters in vapor, forms with it the fleecy or the watery cloud, and retains its precious charge till its service is demanded in rain or in dew, in hail or in snow. As the pabulum of life, the air of the atmosphere exercises still higher functions. It is the food of whatever breathes, the fuel of whatever burns, the essence of whatever grows, the spirit of whatever dies-the soul, in short, of matter-its element when it exists, its residuum when it decays. It is only, however, in its relation to the geography of the sea, that we can treat of the functions of the atmosphere.

tion of heat over the globe, we have shown that there are in the Northern Hemisphere two poles of maximum cold -one in Canada, and another in Siberia; two meridians of maximum cold, passing nearly through the cold poles; and two of maximum heat, nearly at right angles to them. We have shown, also, that the two magnetic poles are nearly coïncident with the poles of maximum cold; and we are therefore led to regard the earth as a great thermo-magnetic apparatus, in which the distribution of its temperature is regulated by internal or external causes, depending upon magnetic, galvanic, or chemical agencies. The difference between the temperatures in the same latitudes (13° in the lat. of 50°, and 17° in the lat. of 60o) on the cold and warm meridians, is too great to be produced by any genial currents in the ocean; and we can hardly conceive how even a much higher temperature than that of the Gulf Stream could, after its enormous diminution by the eastern expansion of the current, affect even the Northern Ocean to any marked extent. That it should affect the inland climates of the West of Europe, appears to us still more problematical. Between the parallels of latitude 30° The variation of temperature in the warm N. and 30° S. of the equator, winds called European meridian, as the cosine of the the Trade - Winds, blow almost unceas latitude, indicates a cause of a more gene-ingly. Those on the north of the equator ral nature than the intrusion of an oceanic blow from the north-east to the southcurrent; and when we consider that this west; and those to the south of the equalaw is indicated also by the temperature tor from the south-east to the north-west. of the earth of springs deeply seated, In their motions, the trade-winds are and beyond the influence of superficial as steady and constant as the current of a agencies we feel that we are not pre- great river, always moving in the same sumptuous in questioning the opinion, that direction, unless when they are occasionthe Gulf Stream, though it may influence, ally turned aside by a desert to blow in does not regulate the climate of the Monsoons, or as land and sea-breezes. The Northern Hemisphere. northern edge of the north-east tradeWith the physical geography of the sea, winds is variable. In spring they are so the atmosphere of the earth has a neces- near the equator, that they sometimes sary and an interesting connection. What reach only to the parallel of 15°. As the moon is to the tides, the atmosphere those two master currents of air are conis to the ocean. We must study the tinually blowing from the poles to the character and condition of the one, in or- equator, it necessarily follows that the air der to understand the motions and laws thus taken from the poles must be reof the other. The air which surrounds placed by other air from the equator. the earth extends at least to the distance This return current must, therefore, blow of fifty miles, growing thinner and thinner in the upper regions of the atmosphere, as it recedes. At the top of the highest and opposite to the wind which it remountains, it is scarcely sufficient to sus-places. Had the earth been at rest, these tain life and to propagate sound. Though it presses upon every square inch of our bodies, we do not feel its influence. When at rest, we are sensible only to its heat or its cold. The aspen leaf rests on its stalk,

winds-the trade and their return currents-would have moved from north to south, and from south to north; but in consequence of the rotation of the earth from west to east, both the direct and counter

currents move in a direction intermediate between the two motions to which they are subject-namely, in south-easterly and south-westerly, and in north-easterly and north-westerly directions. When the north-east trade-winds meet the southeast ones at the equator, they produce a calm, thus forming the belt of Equatorial calms. In like manner, when the direct and return currents from the poles reach the parallel of 30°, they produce a belt of calms, which in the Northern Hemisphere are called the calms of Cancer; and in the Southern the calms of Capricorn. The breadth of the calms of Cancer, and also their limits, is variable. According to the season of the year, they oscillate between the parallels of 17° and 38° north.

Among the meteorological agencies of the atmosphere, its two greatest functions, according to Lieutenant Maury, are to distribute moisture over the surface of the earth, and to temper the climate of different latitudes. Having traveled obliquely over a large space of the ocean, the north-east and south-east trade-winds are heavily laden with moisture when they meet in the belt of equatorial calms. The two currents being thus brought into collision, the air rises upwards, and expanding and cooling as it ascends, a portion of its vapor, thus condensed, descends in rains, which are sometimes so heavy and so constant, that, to use the language of old sailors, they "have scooped up fresh water from the surface of the sea." The waters thus taken up in vapor and precipitated during the collision of aërial currents, and the cold which accompanies them, supplies the great rivers of the world, which conduct them to the sea, to be again raised by the winds and breezes which blow upon its surface. As the great mass of the ocean lies in the Southern Hemisphere, it is a curious fact that the greatest quantity of rains, indicated by its rivers, falls in the Northern Hemisphere. In the Northern temperate zone, the annual fall of rain is "half as much again" as that in the South temperate zone ;* and it is well known that the great water courses of the globe, and half the fresh water, is in the Northern Hemisphere.

In explaining this remarkable fact, Lieutenant Maury states that, in the late part

* According to Johnston's Physical Atlas, the annual average in the North is 36 inches, and only 26 in the South temperate zone.

of the autumn, winter, and early spring of the North, the sun is throwing an intense heat upon the seas of the Southern Hemisphere, and therefore raising a mass of vapor into the upper regions of the atmosphere, from which it is carried in an upper current by the south-east tradewinds, and set free by condensation in our northern winter. When this upper current reaches the calms of Cancer, it becomes the surface wind from the southward and westward, and, cooling as it goes north, the process of its condensation begins. Hence our author concludes that our rivers are supplied with their waters principally from the trade-wind regions, and that this is the reason why the sea water in those regions contains more salt than elsewhere.*

The rivers of the Southern Hemisphere, for similar reasons, are supplied with their waters by the north-east trade-winds; but as the evaporating surface-that is, the area of sea over which they blowcontains, between the parallels of 7° and 29° north, only 25,000,000 of square miles, while the evaporating surface in the Southern Hemisphere is 75,000,000, the quantity of rain which falls in the latter is comparatively small. The mean annual fall of rain, which is evaporated principally from the seas of the Torrid Zone, is `estimated at about five feet. If we suppose it all to come from that zone, it would be equivalent to the waters of a lake 24,000 miles long, 3000 miles broad, and 16 feet deep! and this water is annually raised up into the sky, and brought down again by

* Lieutenant Maury has employed these views in determining the regions where no rain falls, those where it should be a maximum, and those where the climate should be the most equable. The rainless regions are on the coast of Peru, and about the Red Sea, and the Western Coasts of Mexico; and the Deserts of Africa, Asia, North-America, and Australia, are almost rainless. The regions of greatest rains are the abrupt slopes of those mountains which the greatest area of the ocean. They occur in Patathe trade winds first strike after having blown over gonia and to the north of Oregon. The regions of equable climates are under the Equatorial calms, "where the N. E. and S. E. trade-winds meet fresh from the ocean, and keep the temperature uniform also explains why there is more rain on one side of a under a canopy of perpetual clouds." Our author

mountain than on the other. The Andes, for examample, and other mountains which lie athwart the course of the winds, have a dry and a rainy side, the prevailing winds determining which is the rainy and which is the dry side-the weather side, or that on which the wind blows, being the wet, and the lee side the dry one.

the exquisite though complex machinery of the atmosphere, "which never wears out nor breaks down, nor fails to do its work at the right time and in the right way." In contemplating these wonderful arrangements, we see why the earth is round-why its mass and force of gravity is neither greater nor less than it is why the proportion between the land and water is as we find it-why the existing capacity of the atmosphere for moisture has been adopted and why the mountain ranges have their present height, and breadth, and form, and position. To understand these arrangements, or if beyond our capacity, to be convinced of their existence, is a privilege of no ordinary kind. If there is any part of the economy of the material world which seems to be inexplicable and without law, it is the weather with its capricious changes and its ever-varying and mysterious phenomena. Delayed with calms, or baffled with contrary winds-tossed upon a tempestuous sea, or dashed upon the cliffs of the ocean-deluged with a water-spout, or upset by an iceberg-lost in a fog, or struck by the lightning, the sea-faring man can hardly believe that he is suffering under a system of beneficial adaptations necessary for his happiness and even his existence. Nor is the landsman less skeptical when he is personally thwarted in his plans-when his crops are inundated or leveled with the ground-his forests shattered or uprooted-his tender frame fevered with heat or with cold-and the circle which he loves smitten with famine or with pestilence. And yet he ought to know, and if he does not know, he ought to learn, that these apparent evils are the workings of that complex machine, with its pinions of heat and air and water, which feeds and sustains every living thing in the animal and vegetable world. But though it is not difficult to comprehend this general truth, the philosopher is only beginning to understand some of the simpler processes which are under our daily observation; and we can hardly congratulate him on having discovered a single law which regulates the weather. While the astronomer, with his timepiece and his telescope, can predict and exhibit phenomena in the heavens invisible to the human eye, the most weatherwise sage, even with the barometer and thermometer in his hand, and the windgage in his view, dare not, without pre

sumption, anticipate an hour of sunshine or a day of rain.

In his fourth chapter, Lieut.Maury treats of land and sea-breezes, those alternate winds which proceed from the sea by day, and from the land by night. These breezes have their origin in the heating of the land by day, and its cooling by the radiation of its required heat during the night, though they are occasionally affected by other causes. Lieut. Jansen,* of the Dutch Navy, whose observations, couched in language too poetical for science, constitute the principal part of the chapter, is of opinion that electricity, rain, and other causes, have an influence on the regularity of the land breezes; and he goes so far as to conjecture, from very insufficient data, that the moon is also an agent, there being, as he avers, in several localities little land-breeze at full moon, and little sea breeze at new moon.

Among the means of investigating the phenomena of the trade-winds, our readers will hardly believe that the microscope has been highly instrumental. In several localities, showers of dust of a brick-red or cinnamon color are precipitated in such quantities, as to cover the sails and riggings of vessels hundreds of miles from land. These showers produce what the seamen calls "red-fogs," or "sirocco," or "African dust," and they have enabled the meteorologist to establish as a fact, what had previously been the result of theory, that the north-east and south-east trade winds, after meeting and rising up in the equatorial calms, take their observed paths, the south-east trades passing over into the Northern Hemisphere, and the north-east trades into the Southern Hemisphere. By examining the "sirocco or African dust," Ehrenberg found it to consist of infusorial animalcules, and organisms whose habitat is not Africa but the southeast trade-wind region of South-America. In the strikingly similar specimens from the Cape de Verd Islands, Malta, Genoa, Lyons, and the Tyrol, he recognized South-American forms; so that they must have been carried by a perpetual upper current of air from South-America to North-Africa. The rain-dust, which, according to Humboldt, imparts a straw color to the atmosphere, is of a brick-red

* Jansen's Appendix to Lieut. Maury's "Physical Geography of the Sea," translated from the Dutch by Mrs. Dr. Breed of Washington.

or yellow-ochre color when collected in | immense pile and helix, which being exparcels. It falls most frequently in spring cited by the natural batteries in the sea or autumn, generally from thirty to sixty and atmosphere of the tropics, excites in days after the equinoxes; and in order to turn its oxygen, and imparts to atmoexplain this, Ehrenberg supposes that a spherical matter the properties of magnet"dust cloud is held constantly swimming ism.” "With these lights," he continues, in the atmosphere by continuous currents "we see why air, which has completed its of air, and that it lies in the region of the circuit to the whirl about the Antarctic retrade-winds, and suffers partial and period- gions, should then, according to the laws ical deviations." As this dust is probably of magnetism, be repelled from the south taken up in the dry and not in the wet and attracted by the opposite pole towards season, Lieut. Maury is disposed to be- the north." Although we have endeavorlieve that it comes from one place in the ed, in a very brief space, to give our vernal, and from another in the autumnal readers some idea of our author's arguequinox. ment in favor of a relation between the magnetism of oxygen (not the magnetism of the earth) and the circulation of the atmosphere, we can not admit that it is either consistent with fact or sound in theory. Whatever it be which constitutes "the magnetism of the earth," we must look to it as the origin and regulator of any magnetic action which may be found to exist upon the currents in our atmosphere.*

When the opposite trade-winds meet in the equatorial calms and rise up together, Lieut. Maury asks an important question. What makes them cross? What is the power which guides the northern trade to the south, and the southern to the north? And he proceeds to answer it in his sixth chapter," On the probable relation between magnetism and the circulation of the atmosphere." The theory which our author here expounds is founded on the fine discovery of Dr. Faraday, that oxygen gas, which forms one fifth part of the atmosphere, is magnetic; that its magnetic force is diminished with heat, and that the atmosphere is a magnetic medium ever varying in its magnetic power by the influence of natural circumstances. From theory, and some observations by Passy and Bellot, he conceives that the atmospherical nodes or calm regions, or poles of the wind,* are coïncident with the north and south magnetic poles, and also with the poles of maximum cold discovered by Sir David Brewster; and he considers that there is such a physical connection among these three poles as to indicate a corresponding relation between magnetism and the circulation of the atmosphere. * In support of the doctrine of the crossing of the "So wide," says he, "is the field of specu- air in the Equatorial Calm Belts, Lieutenant Maury lation presented by these discoveries, that adduces the fact, stated by Lieutenant Jansen and we may, in some respects, regard this Dr. Moffat, that ozone is most abundant in the Northgreat globe itself, with its cusps,' andern Hemisphere in winds that have Southing in spiral wires of air, earth, and water, as an

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From the currents of the atmosphere our author passes to the currents of the sea, and he sets out with the assumption, "that from whatever part of the ocean a current is found to run to the same part, a current of equal volume is found to return." It is not necessary that the ocean currents run, like our rivers, from a higher to a lower level. While some run on a level, others, like the Gulf Stream, actually run up hill. The currents from the Atlantic to the Mediterranean, and from the Indian Ocean into the Red Sea, run down hill. In order to explain this, in the case of the Red Sea, the surface of which is an inclined plane, Lieutenant Maury supposes its channel to be dry, smooth,

them, and in the Southern Hemisphere in winds that have Northing in them; and, supposing that this remarkable substance is the production of thunder and lightning, he presumes that it may be generated

among the detonations and clouds and rains of the Equatorial Calms." If this be its origin, he then asks, how it "can cross the trade-wind regions except with the upper currents?" We can not answer this and other analogous questions which he very ingeniously puts; but, with all the respect which we have for the opinions and reasonings of our author, we are led rather to question than to maintain the doctrine which he advocates, when it requires such arguments to support it.

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