« 이전계속 »
truth, however complicated we may consider the system in detail, and however puzzled we may be to account for, or reconcile satisfactorily, to our finite reasoning, the various movements which take place.
It is not, sir, that we believe ourselves capable of offering a perfect solution of this obscure problem, we submit these remarks for insertion in your useful publication; but having been long in the habit of reflecting on the various phenomena which we have observed in the progress of our movements in different parts of the world, and of committing our thoughts to paper, we feel it almost a duty imposed upon us as a member of that profession, which claims for itself, the ocean as a home, to place them before your readers.
We need not occupy space by tracing the permanent currents, their general courses are known to seamen, although the continuous lines have not been clearly established. The commencement of the mightiest of these wonderful streams appears not yet to have been discovered. All that seems to be actually known is, that it passes like a sluice round the Cape of Good Hope, is said to cross the South Atlantic, is supposed to flow through the Caribbean Sea, and Florida Channel, along the coast of North America, and curving to the eastward, near the banks of Newfoundland, is lost nobody knows where.
There is certainly something so very astonishing in the contemplation of an oceanic stream, of which, among those of the land, there is no parallel, of so vast an extent, pursuing a devious course, that the mind at once becomes amazed, and the attention forcibly arrested by the subject ; and our surprise is rather increased than diminished, upon finding that this river of the sea, has neither had its origin, or termination unquestionably determined. Considering the course it pursues, would it not be a fallacy to conceive that, like the material symbol of eternity, it has neither beginning nor end.
In the consideration of the permanent currents, which may not inappropriately be termed oceanic rivers, it has always been usual to seek for causes alone on the surface, whilst the hidden operations that may be passing in the deep abyss, have been unheeded.
We know not by any experiment, what effects* if any, take place at the bottom of the ocean, near to where volcanic action is active ; for instance ; around the Azores, Iceland, &c. Although it has been surmised that the tropical character of the Mediterranean is owing to volcanic heat ; and we think it highly probable, that the mildness of the climate about Cape Horn, may be accounted for, from the same agency.
The temperature was found by Sir J. Franklin, and Capt. Buchan, to be greater beneath, than at the surface, in the Northern Ocean, where ignivomous operations are carried on to a great extent.
Ilow deep does the superior warmth of the Florida stream extend ? This, sir, is a question worth the trial, because if it were found deep seated, we might not unreasonably infer, that some communication
• We allude to the effects of heat, on the atmosphere and water.
exists between the active volcanoes of Guatimala, and Yucatan, which peninsula, with its spinal range of mountains, lies in the direction with the course of the stream, through the Strait. Would it be unphilosophical to connect igniferous action, supposing a subterranean communication, with the warmth and flow of that current ? These are questions, however, unlikely they may appear to our present notions of the streaming of lengthened portions of sea water, that are not unworthy of attention.
Jets d'eau, hot, are ejected ninety feet high into the air in the Icelandic sea. Why should we limit the effect to a vertical action only? Would there be anything unreasonable, after that fact, in enlisting a horizontal play of this active elemental strife? The misfortune seeins to be, that our minds are so wedded to abstract ideas, that, it becomes difficult from, perhaps, indifference, or sheer indolence, to entertain enlarged views; and the individual who starts hypotheses, which, when calmly examined, may have nothing improbable in them, but, from their novelty alone, create distrust, is set down as permitting his reason to “run riot."
We have, sir, been so long accustomed to look to the winds, upon the abstract consideration of their often violent action and constancy, in certain parallels, as the cause of currents, that without farther trouble on the occasion, we rest satisfied with the explanation; at the same time to all seamen, who have made observations to any purpose, it is well known that such assumption is not borne out by facts. If a given cause is inadequate to the production of an apparent effect, is it not an absurdity to insist upon the single application of it?
We find in almost all parts of the world that there are rivers, some of great magnitude and extent; generally taking their rise from elevated lands; and if we reason from analogy, why should we not consider that there are also subterranean and sub-marine rivers, issuing from unceasing reservoirs in the earth?
At a first view, this idea may startle the sober minds, of some of your readers, but, there is not, sir, any thing unreasonable, or even fanciful in the supposition.* By a natural hydraulic process it may be easily reconciled.
Let us for a moment banish the old notion, that there are no other rivers but those which run on terra-firma; suppose the source to be situated on elevated land, and that by a subterraneous channel this supply is carried gradually lower and lower, until it vents beneath the surface of the ocean; and that, as it flows downwards in its hidden course, it meets with various accessions from other streams, and its volume and capacity become continually augmented, until it arrives at its place of exit. The impetus acquired in the descent, and the less specific gravity of the fresh water, if the depth proved not insuperable, would be equal to the ascent towards the surface, against the incumbent pressure
• It is not improbable, that before the fact was determined, a stand would have been made against any opinion stating, that some rivers run inland from ibe sea sbore, because such tallied not with pre-conceived ideas on the subject.
of the sea, which being easily moved, may attain a corresponding motion, and assist in perpetrating a permanent stream. Is there any thing unreasonable in this?
The question may, indeed, be started as an objection; that such stream ought to be less saline, than the sea-water, on either side; true, but has any one tried the experiment? Capt. Manderson says, the Florida stream is fresher than the ocean water; and Humboldt, that it is salter. Who is right? It is probable, however, that to a certain distance only, the water of the stream would be much less salt, than that of the ocean, through which it presses, the particles of the fluid, from their mobility, acquiring an impulse, according to the power of the initial velocity.
Another objection may be, that, the Amazon, Orinoko, Congo, and other great rivers, pursue their courses, comparatively, but to a very limited extent in the ocean. Capt. Sabine has dispelled some of the mist which has hitherto involved this very question; but, who has traced those streams to the ne plus ultra, into the wide ocean! They have been crossed at two or three hundred miles from their respective places of discharge, but what navigator has followed their course from the land, to solve the interesting question? Who knows but that these rivers, and others of magnitude, by pressing the waters of the ocean onward into a stream, may after all, be the origin of some of the many currents which navigators report “far far at sea.”
Besides, may there not be sub-marine mountains, which by guiding and restraining the deep-seated current, perpetuate its flowing to a great extent? If, sir, we could possibly rise artificial mounds round the globe, a gigantic aqueduct, is there a single engineer, that would be bold enough to gainsay that, such a stream as the Amazon, would not flow throughout the whole distance? Fresh-water founts in the sea, are common in the vicinity of the Florida Channel; one we have seen; and subterranean rivers are well known to exist; we ourselves have heard more than one roaring and dashing their foaming and hidden waters over the impediments to their free course, whilst hastening in their descent to the ocean.
We can, sir, only judge from the wonderful phenomena, which are known to exist in various parts of the world, but principally from those which take place in the Pacific, what is passing in the bed of the ocean. Let us reflect only, for an instant, on the vast scale upon which nature in her hidden laboratories carries on her works, to accomplish ends, the design of which, the capacity of man is unequal to account, and we shall no longer consider it chemerical, that subterranean rivers may produce super-currents of the ocean: if by fire and water she is capable of rising hundreds of miles of the bed of the ocean, may she not in her unlimited power of action, produce a rush of water from inland reservoirs, that, shall form a stream hundreds of miles in extent? Shall the mere mortal presume to fix limits to her operations?
To conclude this long yarn, Mr. Editor, one could almost wish to possess for a “wee time,” the gill-lungs of the mermaid, fanciful or not, to take a plunge into the deep recesses of Nuptune's domain, and peep
at the wonders below. One could then, sir, promise you (saving tintereros, huge polipi, and such aquatic rovers,) a rich harvest for the “ Nautical !” What a fidget the quadrupled eyed antiquarians would be in; — “bless my day-lights (as Jack lips it in vulgo-nautic,) how the knowing ones would stare, — and well they might:
For, there, " sans doute"
IMPROVEMENTS IN THE CONSTRUCTION OF LIGHTHOUSES.
(From the Shipping and Mercantile Gazette.) SIR.—As the colunins of your journal are, at all times, open to suggestions in any way calculated to promote the general interests of this great country, and to protect the lives and properties of persons employed in navigation, I beg to hand you a description of an improved method of constructing lighthouses, which I trust may be deemed worthy the attention of your readers, especially as the subject on which it treats so greatly tends to the promotion of our national wealth, and so closely connected, or, rather, forms the main link of the great chain of civilization. While it is obvious that every means should be used to facilitate the workings of the great branches of industry referred to, the numerous and fearful shipwrecks, which are continually occurring on our coast, are sufficiently cogent to assure us, that our coast is not sufficiently lighted to warn the enterprising mariner of his danger in time to prevent accident. The vast amount of shipping to and from our ports, and the yearly increase of the British commerce, both by sea and land, calls upon the legislation of the British empire for a more improved system of lighthouses. From the efficient state of our steam ships, we are no longer dependent on the winds and tides for an intercourse with our colonies, and other nations; butaccess to all parts of the globe is now perfectly easy. Much remains to be done at home, to render the approaches to our ports more distinct; but so long as the Goodwin Sands, and other such places, remain unlighted, life and property must be considered in danger. Sir, with your permission, I shall call the attention of your scientific readers, and, more especially, the elder brethren of the Trinity House, to the means by which a substantial foundation, for lighthouses, on all such dangerous places, might be effected at a moderate expense, and without any risk. The system I propose is by no means of a novel description, but has been long in extensive use for sinking operations, in mining districts, to effect a passage through running sands.
It is well known that, in shaft sinking, running sands of the most formidable nature have presented themselves to the miner, who, on making the discovery, immediately resorts to what he terms a sinking tube-the NO. 1.-VOL. XVII.
size of the shaft, including the brickwork. The tube, or cylinder, is, in most cases, made of wood; and, when placed in the required position, is weighted with brickwork, and so forced through the sand; and, by these means, the brickwork casing is effected. But as this system is so practically understood among your practical readers generally, a detailed account of the operation would be useless. It is evident that, if by means of a cylinder, a passage can be effected through the running sands in a shaft, the same means could be used on the Goodwin Sands, and other dangerous spots, with the same success.
E, E, double rows of piles, for the protection of the cylinder.
F, chalk formation.
E, E, wood planking inserted between the flanges, to reduce the friction in sinking the cylinder.
Fig. 2, A, the cylinder -B, timbering, to secure the cylinder against external pressure.
C, double rows of piles, to protect the cylinder and concrete.
D, space between the piles and cylinder to be filled with concrete.
From the many inquiries I have made respecting the depth of the Goodwin Sands, I believe they are not more than 30 feet thick-at the bottom of which is the chalk formation. If we can by any means get to the chalk, we have at once a foundation for the lighthouse, which would resist every storm, I should propose to construct a wrought-iron cylinder (say) three-eights of an inch : boiler (plate-iron) of 30 ft. diameter, which would give a sufficient base for a lighthouse of 120 feet above high-water mark. Such a light would be seen at a suitable distance. The cylinder