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these clergymen accept of Articles in a non-natural sense which our author once denounced, hold possession of the most responsible positions in an orthodox Church, and hope to lead that Church itself into their own path, “whither is abundantly obscure, but whence is very plain.”
Art. II.-ATMOSPHERIC AND OCEANIC CURRENTS.*
Currents and Changes of the Atmosphere and the Sea. By M.
FELIX JULIEN, Lieutenant in the Navy, and formerly a Pupil of the Polytechnic School. One volume, 8vo. Paris : Lacroix &
Baudry. 1860. THE earth floats in the midst of a covering of gas and vapor, according to some, about thirty-seven miles, and others sixtytwo miles in depth; a true atmospheric ocean, of which the changes and storms yield in no respect to those of the ocean, to which they have very close relations. It is at the bottom of this immense aerial sea that men and other animals exist, just as the fishes live in the waters.
Although the fostering care of the Creator placed his cradle in privileged places, man must have been early astonished at the spectacle that the various atmospheric changes presented; changes, of which without doubt he was at first an astonished witness, and of which, more than once, he has been the victim. The contrast between these changes and the general harmony of the universe was not long in arresting his attention. But for a long time he only saw in these phenomena the effect of blind forces, and could not assign them to any other cause than the caprice of nature. What did we know even yesterday? What know we to-day? By turns Galileo, Bacon, Vossius, and, in later times, Halley, d'Alembert, and Chevalier Coudraye, the least known of all, endeavored to resolve the problem ; but too often, instead of having recourse to observations, which alone could give the clue, they demanded an impossible solution from futile mathematical abstractions. So that, excepting the trade-winds, and the monsoons, which are only the periodic reversions of the trades, the winds continued to be considered essentially irregular.
* The following article, with its sequel, which will appear in our July number, translated from "Le Correspondant," while nominally a review of a work by M. FELIX JULIEN, Lieutenant in the French Navy, is in effect a masterly statement of the theories as to Atmospheric and Oceanic Currents advanced by our countryman, Lieutenant M. F. MAURY, Superintendent of the National Observatory at Wash. ington. Lieutenant Maury's work on the “Physical Geography of the Sea" has excited more attention, both in America and Europe, than any other scientific work issued within the last fifteen years. A new edition, entirely rewritten and greatly enlarged, has recently been published simultaneously in New York and London. It contains all the results of the extended series of observations carried on under the superintendence of Lieutenant Maury, brought down to the latest period.-ED.
At last a man has arisen who, fortified by his own experience, and above all by an abiding faith in the harmony of creation, has resolutely applied himself to the research of the mysterious laws that govern nature, and has attempted to demonstrate the regularity of two things regarded heretofore as the types of inconstancy and change, namely, the winds and the waves. This man, whom posterity will regard as one of the glories of the American Navy, and whose name, but yesterday almost unknown to us, will become more and more celebrated, is—the reader has already named him—Lieutenant Maury. Enrolling all the navies of civilized nations in both continents under the peaceful flag of science, Maury has made himself, for some years, the center of information received from all parts of the world. From this enormous mass of observations, made in all latitudes, and discussed in an international scientific congress held at Brussels in August, 1853, the learned American meteorologist, with the sagacity that only belongs to genius, has formed, as two grand syntheses, his theory of oceanic currents and his very ingenious system of the direction of the winds.
Our readers will understand that we cannot, in these pages, set forth as a whole this double theory, of which a thousand details surround the entire subject of their ingenious system. We will content ourselves with sketching the principal features, drawing aid from the most recent and most reliable works on meteorology, and especially from the book of M. Julien, which is the latest resumé and one of the most complete with which we are acquainted.
I. ATMOSPHERIC CURRENTS.
It is known that the atmosphere is divided, from one pole to the other, into at least nine distinct and parallel zones, four of currents, and five of calms or capricious breezes. The latter, 30 or 40 in breadth, are the equatorial, the two tropical, and the two polar zones. The four zones of currents, or of winds, are the four intermediate zones; that is to say, the two that extend north and south from the tropical calms to the polar calms —this is the region of free or prevailing winds—and the two that separate the equatorial calms from the tropical calmsthis is the region of the trades, of which the free winds are only the continuation and, as it were, the prolongation.*
Do these different zones form regions separate and distinct ? In other words, do the zones of calms arise as impassable barriers before the zones of currents, preventing between these all communication, all interchange of gas and vapor, as was so long believed ? Such was the problem to be resolved, a problem intricate and delicate.
On looking at the map of the world, Maury was struck with this singular fact—that nearly all the large rivers of the world arose in the northern hemisphere, although the oceanic surface, and, of course, evaporation, was much less than in the southern hemisphere.
How could this surprising fact be explained except by supposing a continual exchange of moisture between the two hemispheres, and that, too, in despite of the zones of calms ?
The observation of facts was not long in giving reason to this bold hypothesis. From these facts we will choose the two following as being the most conclusive. The analysis of the air taken from all latitudes proves it to be identical in constituent particles everywhere, notwithstanding the very different conditions of cold and heat; an evident proof that there are incessant ways of communication between the different zones of the atmosphere. The second fact is still more striking : the showers of dust which have been so often observed at Genoa, Malta, and other places. Now the celebrated naturalist of Berlin, Ehrenberg, provided with his powerful microscope—that wonderful instrument that reveals the boundaries of the infinitesimal world, as the telescope of Lord Ross reveals those of the universe—has discovered in the matter that composes these dust showers the débris of infusoria and of organic matter brought from South America, and which could only reach Europe by traversing the regions of calms. When, in his distant journeys to the torrid zones, Alexander Humboldt observed the formation of whirlwinds of dust, of which he speaks, the illustrious savant did not suppose that this dust, carried by the winds above the equatorial and tropical calms, would fall in showers upon the European shores, and carry there the proof of the upper currents of the atmosphere.
* The free winds of our hemisphere blow from S. W. to N. E., those of tho western hemisphere from N. W. to S. E.; the trades of the north blow from N. E. to S. W., those of the south from S. E. to N. W. The free winds of the north aro the prolongation of the trades of the south, and the free winds of the south are the continuation of the trade-winds of the north,
These facts, and many others that want of space will not permit us to notice here, suggested to Maury his theory of winds, a theory subtle as it is ingenious, and of which we will endeavor to convey an idea.
Above the regions where the four zones of surface winds extend, according to the sagacious meteorologist, four higher and parallel counter-currents blow opposite to the first, charged with re-establishing continually the equilibrium of the atmosphere. The intermediate calms are produced, at the equator by the meeting of the trades; at the tropics by that of the superior opposing winds. The expression “calms” is relative, the atmospheric ocean having, no more than the other ocean, absolute repose; this word only signifies the cessation of the horizontal motion of the air and the commencement of its double vertical movement, ascending in the regions of equatorial and polar calms, and descending in the tropical zones; a movement which the barometer points out here by its elevation, there by its depression.
If we follow, in thought, a particle of air in its restless voyage around the globe, we shall see it carried in turn, by the superior currents and the surface winds, to feed alternately the trades of the south and the free winds of the north in going, and the trades of the north and the free winds of the south in returning. All the intermediate places will be overleaped by it in the higher currents. What force determines these currents and drives them thus in opposite directions? What power prevents the dry and moist air from commingling in the zones of calm, and sends the first to the equatorial seas, from which it will soon imbibe moisture, and the second to the colder regions, where it carries the rain with which it is surcharged, without ever the confusion of the two disturbing the harmony of this marvelous circulation ? Maury supposes that in these phenomena are concerned the influences of electromagnetism, that mysterious and powerful agent so universally present and as yet so little known.
The rotation of the earth's crust around its central mass, which is in a state of fusion, and whose revolutions are less rapid, produces, according to M. Babinet, a double current of electricity, negative in the liquid, and positive in the solid matter. This rotatory motion being greatly accelerated at the equator, the electricity is formed there in much greater abundance. The atmospheric currents, taking up the positive, (positive electricity being in excess,) carry it to the poles, where it is accumulated, and where, meeting with the negative electricity, it produces the magnificent electrical storms which are called Auroras—the intermittent sun of those desolate regions where the sun does not shine. It is to this same polar electricity that Maury attributes the whirl of atmospheric currents around the poles. Faraday has recently demonstrated the magnetic properties of oxygen, a gas that composes the fifth part of the air we breathe. Do not these properties assist in the circulation of the atmosphere? The positions assigned to the magnetic poles—the pole of the winds and that of greatest cold—are nearly identical. Can this be pure coincidence ? What force, unless it be electricity, draws on the hurricane and makes it whirl in the same manner that the spiral of the polar current does, to which it is nearly related, that is to say, from right to left in the northern hemisphere, and from left to right in the southern ?*
* The Newtonian gravitation is, perhaps, only a phenomenon of the same kind. The law of universal attraction was only to Newton himself but the rule of a fact and not of a cause; bodies are not attracted in truth, but pass from one to the other as if they were attracted. The effect only is constant, the cause is unknown. The dynamic power of the solar heat would be, according to some savans, more than sufficient to determine the rotatory motion of the planets. For what is this solar heat itself except an electrical phenomenon, according to the most generally received opinion? It is true there are those who assign as a cause for it the im