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ART. VI.-The Physical Geography of the Sea. By M. F. MAURY, LL.D., U.S. N., Superintendent of the National Observatory. An entirely New Edition, with Addenda. New York: Harper & Brothers. London: Sampson Low, Son & Co. 1857. Pp. 360.

MOST of the elder part of the present generation can remember the time when geography was one of the dullest and most uninteresting of the lessons they had to learn. And it is no wonder that it was so, when one considers the mode in which it was taught, and the books from which it had to be learned. It seemed, in fact, to be but a dry catalogue of names of rivers, towns, cities, mountains, gulfs, lakes, peninsulas, &c., without any help afforded to the memory of the reader by reference to other branches of knowledge, either for the explanation of the meaning of the terms used, or for exhibiting the influence that physical conformations have had on the state of society in general, and the condition of those people who have at different times occupied the different regions of the earth. We can well remember when it was thought too great an indulgence to be allowed to say a geography lesson with the map before the learner's eyes, and when, indeed, a map was by no means thought an indispensable adjunct to a book on this subject. It may casily be supposed that the amount of knowledge acquired in this way was neither great, nor easily retained in the memory; it consisted, for the most part, of a catalogue of names of places, and the nearest approach to things of human interest was made in the enumeration of the imports and exports of the different countries into which the globe was divided. We believe the philosophy of the subject never reached so far as to give the reasons why great towns are usually placed upon some large river.

Certainly, things are considerably changed since the commencement of the present century; and if there is, as cannot be well denied, a good deal of dabbling in science, we must confess that there are some subjects even of a scientific nature, with which we would rather people had a superficial acquaintance than none at all. And perhaps in no subject has so complete or so satisfactory a change taken place, as in that of which we are speaking. Moreover, the subject has become popular in proportion as it has become deeper; its results are so immediately practical, that almost all classes of society are interested in them, and perhaps even to children in a parochial school this may be made the most interesting of all the subjects taught.

Even the mere names of the great divisions of the science belong to the present century; and such terms as physical, mathematical, and political geography, which are now known to everybody, were but a few years ago new even to scientific men. We need not here attempt to investigate how far the kindred subject of geology, by settling down into a definite science, has contributed to this result. The physical sciences must make progress together, and the more nearly akin they are to each other, the more will the advance of one affect the progress of another. And the particular science which we are now recommending to our readers may perhaps be considered to be one of the links which connect geography and geology; or at least must be said to be mainly indebted for its existence to the rapid progress which both these sciences have of late years made. We need not defend the title which it has adopted, which, we must confess, sounds to our ears somewhat like an Irish bull. We can only say that it has established itself with its present name, and that it would be much less easy to deprive it of the name which it has assumed than to enlarge the definition of geography to which we have been hitherto accustomed.

A few years ago we could have imagined a reader asking, What can there be to be known of the bed of the ocean? and how is it possible to learn anything about such a subject? and to what practical use could such knowledge be applied? These are questions which we may spare ourselves the trouble of saying anything more about at present, than barely to remind our readers, that perhaps before these pages meet their eyes, the eastern and the western world will have been united by the cable which is now being laid down between Ireland and Newfoundland-that it will be possible to transmit a message in an instant of time, from the Old to the New World-that an event which is chronicled as happening at noon on this side of the Atlantic, will simultaneously be recorded as happening a few hours earlier on the same day in the other hemisphere. Truly, the results of science are wonderful. We remember hearing an American in his own country making boast that he had telegraphed from California to New York, and had received his answer from his partner in the latter place in the course of the same day, the sum of money which he wrote for being paid into his hands only a few hours after he had asked for it. But probably even American sagacity would scarcely at that time have believed in the possibility of the same being done between two places separated from each other by the breadth of the Atlantic Ocean. Yet this is only one of the many practical advantages that have already resulted from the study of this juvenile science. For the interest which is generally taken in this subject, we have a

sufficient voucher in the fact that Lieutenant Maury's work, which we have placed at the head of this article, and of which we intend to give some account, has, in less than two years, reached its sixth edition. The treatise itself originated in an attempt made by its author to collect and chronicle the experiences of navigators as to the winds and currents of the ocean. Every one knows, in whatever department of life he may be employed, how dearly bought experimental knowledge frequently is; perhaps sailors, more than any other class of men, are exposed to the hazards attendant upon inexperience and ignorance. To remedy this state of things, and to supply the young navigator with that which he could not have of his own, The wind and current charts' were published. In them it was proposed to exhibit to the navigator the tracks of all vessels that had preceded him on the same voyage, with the winds and currents that had been met with at all the different seasons of the year, together with the temperature of the ocean, and the variations of the needle; and thus he might be enabled to set out on his first voyage with all the amount of experience he might have derived from having made the same voyage many times before. In stating the matter thus, we are estimating the advantages of such a chart at the lowest possible rate. It is obvious, that as time goes on, if a sufficient number of persons can be induced to co-operate in the work, these charts may furnish considerably more information than the experience of the longest life, even though spent in continually traversing the same path, could possibly supply. These charts were not long in attracting the attention of navigators, and all were invited to contribute their quota towards the bringing them nearer to perfection, an additional inducement being held out by the promise of a copy of the charts and sailing directions that might be founded upon the observations of any who would take the trouble to keep an abstract log of their voyage, and forward it to the Observatory at Washington. And thus the author tells us in his Introduc tion, there were in a little while more than a thousand navigators occupied incessantly over all parts of the ocean in making and recording observations upon a uniform plan, and thus adding to the amount of the knowledge we possess of the currents of the sea and other phenomena connected with the subject of physical geography. The important results thus elicited attracted the attention of the commercial world; and no wonder, when it is considered that amongst these results was the reducing the time of sailing from New York to California, from 183 to 135 days, and the consequent saving of a large per centage on the freight of goods, a saving which may be estimated at nearly one-fourth of the whole expense of transporting goods between those two

places. It was impossible that an undertaking which had already produced such good effects, and was sure to effect still greater results, should much longer remain a merely national concern; and accordingly in the year 1853, the Government of the United States proposed to the maritime states of Europe to hold a conference at Brussels, on the 23d of August, to take into consideration the advantages of a combination of all friendly nations for this purpose. Some other nations which were not represented at the conference have since offered their co-operation, and we are glad to think that, independently of any advantages that may accrue to science and commerce from this joint effort, it will tend in some degree to establish amicable relations between the different nations of the world. The observations are to be carried on alike in peace and in war; and in case any of the vessels in which such observations are being conducted should be captured, the abstract log is to be considered sacred.

It is scarcely possible to estimate the rapid progress which this science is destined to make, with such an immense number of observers stationed all over the sea,-the subject itself, too, possessing so large an amount of interest, and suggesting so ready a return for the labour bestowed upon it. The readers of this volume, therefore, will not be surprised to find the author speaking of his work as intended to show not merely the present state of the science, but its progress from time to time; nor, we hope, will its purchasers be annoyed at thinking that the value of the copy which they possess is gradually diminishing, as successive editions suggest new explanations of phenomena only half explained or erroneously interpreted before. Already the author speaks of having been obliged to revise his fifth edition, recasting parts, omitting other parts, and adding the results of fresh investigation. And in a postscript, dated December, 1856, he adds a piece of information, which at the present moment will be read with interest, that on the deep sea soundings along the great telegraphic plateau, stretching from Newfoundland to Ireland, there has been discovered a line of volcanic cinders, stretching for a thousand miles, and reaching entirely across the Gulf Stream where it is crossed by the submarine telegraph. A detailed account of this wonderful discovery has been thrown into the Addenda-from which it appears that the line of volcanic débris extends from about lat. 50°, long. 38°, to lat. 52°, long. 16°, and that about midway between the extreme points of longitude, i.e. about 27°, the volcanic matter is most abundant.

'It was thought they might possibly be steam-boat ashes, as the steamers that ply between this country and Europe pass that way. Specimens of these

were obtained from the ash-pit of the "Baltic" and other sea-steamers, and examined through the microscope. The examination only satisfied the Professor still more completely as to the volcanic origin of the others.

'Thus the question is fairly presented, Where did these "Plutonic tallies " upon the current of the ocean come from? Did they come from the volcanoes of Mexico and Central America, which have been known to cast their ashes into the Gulf of Mexico, and even as far as the Island of Cuba? If so, the Gulf Stream would have strewed them along the coast of the United States. But specimens from the bed of the Gulf Stream off our coast have been obtained by the Coast Survey, and subjected to the microscope, and no volcanic cinders have been found in them. This negative fact, together with the positive one that they are heavier than the organic tallies which mark the footprints of the Gulf Stream as it travels across the ocean, seemed to place those volcanoes as the source of these cinders out of the question.

'Nor do I perceive by what channel they could be conveyed to the place where the deep sea apparatus fished them up, from any of the volcanoes that are now in activity. They were out of beat of the East Greenland current, and seemed to be too heavy to carry far. I, therefore, turned to the region of extinct volcanoes, and was immediately led to suspect the Western Islands as the probable source. The fact that the cinders were coarse and heavy in comparison with the shells among which they were found, is very suggestive, for it tends to confirm this conjecture. That no traces of volcanic action are found except in the deep trough of the Atlantic, would seem to indicate that in this part of the Gulf Stream they had, on their way to the north, sunk below the submarine step which leads up from the depth of the ocean to soundings off the Irish coast.

"These specimens-bits of down from the bed of the ocean-appear fully to confirm all that I have previously advanced concerning the bottom of the deep sea and the adaptation of this part of the Atlantic for a telegraphic cable. My investigations show that the bottom is so free from currents and abrading agents, that a rope of sand, if once laid there, would be stout enough to withstand the pulling of all the forces that are at play upon the bottom of the deep sea.

The discovery of facts like these has proved of the greatest value to those concerned in establishing lines of submarine telegraph. The French Government, in ignorance of the status of the deep sea, has made two attempts to lay a cable from Sardinia to Algeria. There was failure each time, with great loss, for,the cable was one of iron wire, of immense weight, and stout enough to hold the largest ship; but the currents and the storms parted it, or made it necessary for those on board to cut or perish. Its core was of gutta percha, in which were contained the conducting wires.

The systematic attempt to explore the depths of the sea, and to investigate its winds and currents, which has been inaugurated at the National Observatory, has brought to light the fact that the core alone, without the iron cable or any casing save that of the insulating material, is strong enough to resist all forces at the bottom of the sea; that the forces of the currents through which the cable has to sink, and while it is sinking, are the forces, and the only forces, which try its strength; and if resistance be offered, no cable, as the French have proved, is strong enough to withstand them and sink. It was a cable of this sort which was lost in the laying between Newfoundland and Cape Breton, during the summer of 1855. The currents of the sea are to be overcome not by resisting, but by yielding. The sea, if obstruction or resistance be offered to its waves, will dash the strongest works of man to pieces, and sport with the wreck like toys; while the tiny nautilus, by yielding to them, will defy the most violent ragings of the sea, and ride its billows triumphantly in the utmost fury of the storm.