A GREAT SEA-WAVE.

Samoa Times and South Sea Gazette, Issue 5, 3 November 1877, Page 2

A GREAT SEA-WAVE.

(From the " Spectator.") The gnat sea-wave which, after the I recent earthquake at Peru, swept acios! ! the Pacific to the Sandwich Islands, i affords bash illustration of the vital 'energy which still pervades the flame of our earth, if those theories lie sound according to which each planet during its extreme youth is as a sun glowing with fiery heat, and in extreme old age is. like our moon, cold (save when the sun's rays pour anon it) even in i(< very centre, we should regard the various portions of the middle age of o planet as Indicating more or Um nf vitality according w the situs of iutcmal h- at

and activity vera great** or less. Assuredly, thus viewing our Salth, we have no reason to accept the im -lam-holy doctrine that she Uapproaching the stage of planetary decrepitude. She .-till shows signs of intense vitality, not indeed that all parts of her surface are moved at this present time by what Humboldt called " the re -action of the interior." In this respect, doubtless, changes -lowly take place, the region of disturbance at one time becoming after many centuries a region of rest, and " vice versa." But regarding the earth as a whole, we find reason for believing that she still has abundant life iu her. The astronomer who should perceive, even with the aid of the most powerful telescope, the signs of any change in another planet (Mai's, for example, our nearest neighbour among the superior planets), the progress of the change being actually discernible as he watched, would certainly conclude that the planet was moved by mighty internal forces. Now it is not too much to say, though at first it may perhaps seem so, that the mighty sea-wave which, on May 10, rushed in upon the shore of the group of Sandwich Islands, would have been discernible from Venus, supposing an observer there hail been watching the earth with a telescope as powerful as the best yet made on this earth. The wave was caused, as we know, by a tremendous subterranean disturbance in Peru a lew hours earlier. Here, at least, was the centre of subterranean action, for a land wave also travelled from that region along the Pacific coast of Mexico, and was felt at the Sandwich Isles, where the Kilauea volcano was set in action almost at the same time that the sea-wave came in. But there can lie no doubt whatever, that, as in the case of the great Peruvian earthquake of August, I Mis, the sea-wave had its origin not in

the local subterranean disturbances, but in the great upheaval by which Iquique and other places were destroyed. We shall, no doubt, hear before long, as in that ease, of the arrival of the great wave at the Samoa Isles, at the Japanese Archipelago, on the shores of New Zealand Australia, and so forth. Now, the great circular wave which spread on May 10 last, from the Peruvian shore as a centre athwart the entire Pacific was probably not felt by a single ship in the open sea, any mure than the still vaster wave of the 13th and 14th of August, 180S, and for the same reason. With a height of some fifteen feet (or thirty fed vertical difference between crest and

I hollow), the wave had yet so gentle a slope that, though it rushed at the rate of three or four hundred miles an hour across the Pacific, the rise and fall of a ship upon its surface would be altogether imperceptible. The great sea-wave, as .Mallet. lou_r since pointed out,consists, in the deep ocean, of "a long low swell of enormous volume, having an equal slope before and behind, and that so

gentle that it might pass under a ship, | without being noticed." And we are told. I in fact, by a modern writer, that during the rush of the great .sea-wave across the Pacific on August 13-14, 1S(>8, though ' where the wave reached the Island shores it seemed as though the land were fast sinking bodily into the ocean, and then rising bodily out of it, " there was not one among the hundreds of vessels which were sailing upon the Pacific when it was travei-sed by the Seawave in which any unusual motion was perceived." How, then, it may be asked, can we suppose that a wave which was not perceived by those actually sailing upon the ocean traversed by it, could have been visible with suitable telescopic power from a distant planet ? The very circumstance which rendered the rise and fall of ships upon the sea-waves of lHb'B and of last .May imperceptible assures us that the progress of the wave would so have been visible. Besides its enormous range in length, for when it struck the Sandwich Isles its crest must have formed the arc of a great curve, having for radius the distance of 0300 miles, separating that group from Peru, the wave had great breadth, otherwise, its height being about ISO feet, the rapid advance, of the wave would have caused a rapid rise and fall instead of a slow motion only discernible along shore-lines. Probably the distance from valley to valley, on either side of the mighty crest of the wave was not less than 200 miles in the open sea. So far as mere dimensions,

then, are concerned, the great wave would certainly have been visible from a planet placed as Venus is, when most favourably situated for observing the earth. To show this, it is only necessary to point out that Venus is then much nearer to us than Mara ever is, that the entire diameter of Mars is but about 4.300 miles, while the radius of the great Wave, when it reached the Sandwich Isles, was fully (iOOO miles, and that its probable breadth of 200 miles very far exceeds the breadth of many of the well-

known markings upon the planet Mars. But it may lie asked how the wave would become discernible at all, viewed, as it were, from above. How should an observer in Venus know that the highest part of the wave was thirty feet or so nearer to him than the hollow of the valleys on either side of it 1 The way in which the wave would become visible corresponds In some degrees (0 the wav in which those strange radiations which extern! from several of the lunar craters are visible, though they have vary little elevation, cast no perceptible shadows, and are many of them (indiscernible when other lunar features are clearly j soon, and become discernible only when those other features are scarcely visible jut all. Under the sun's rays, the two opposite faces of the advancing wave would be dirtcrctttly Illuminated <

U.v a hundred miles broad, be it remembered, would catch the Hgkt »°» fully than the ocean as yet undisturbed, while the other would catch the light less folly. Thus the mijhty arc of the wave would appear as a double arc, onehalf of its breadth befog bright, the other (relatively) dark. we do not say that the wave would bo a very striking or obvious feature of the earth's disc as seen from Venus, but that it would be discernible under the same telescopic power which the Herschels.Lassell, Rosse, mid others have applied to the celestial objects as seen from the earth, we have little doubt If so, since not only would it be perceived as a new feature, but also its motion across the Pacific be traceable, and the transcience of the phenomenon quickly recognised it would afford observers on that planet the clearest evidence of the activity of subterranean forces within our earth. Those among the observers living on Venus who were not content merely to observe, but exercised also their reasoning faculties to determine the meaning of what they saw, would perceive that on or about August 13-14, 1808, and again on May 10 last, tremendous throes had shaken some portion of the southern half of that long double continent lying north and south which they have long since recognised

on our globe; that the waters of the ocean had thus been mightily disturbed; and that a great wave, or rather a succession of several waves had swept across the largest of the terrestrial oceans. They would be able even, by noting the velocity and variations of velocity of the great wave, to determine the depth of the Pacific Ocean, and the manner according to which the depth varies in the neighbourhood of different island groups. It is not altogether impossible, indeed, that what we have here described may actually have occurred, though on neither of the occasions when the Pacific has of late been swept by a sea-wave was Venus

very .suitably placed for observing our planet. Apart from thoughts such as these, there is much in a phenomenon like this great .sea-wave well worth considering. When we recognise in tlio subterranean forces of our earth an energy competent to disturb the entire surface of the Pacific, we perceive how vain are the fears of those who imagine that the earth's Yulcauian energies are very nearly exhausted, There is nothing to show that at any time of which geology affords evidence throes more mighty than those which have shaken Peru and Chili within the last half-century have disturbed any portion of the earth's j frame. [n former times indeed, when

geologists were accustomed to regard the processes of an entire era as completed single throe, men might well believe I that i.\»o north Wl »...«w i,*w >«M>ttve I quiescence. But now that close study j has enabled them to separate the effects of one process from those of another, to recognise—not in full perhaps, but in great degree—the influence of time as an important factor in geological development, they are able to make a juster comparison between past and present disturbances. The result is that, although we cannot doubt that the earth "is" parting with the heat which is the source of its V'ulcanian energies, we find every reason to believe that the loss of energy is taking place so slowly that the diminution during many generations is altogether imperceptible. As a modern writer lias remarked, when we see that while mountain ranges were being upheaved or valleys depressed to their present position, race after race, and type after type, lived out on the earth, "the long lives which belong to races anil types, we recognise the great work which" the earth's subterranean forces are still engaged upon. Even now continents are being slowly depressed or upheaved, even now mountain ranges are being raised to a different level, table-lands are being formed, great valleys are being gradually scooped out, old shore-lines shift their place, old soundings vary, the sea advances in one place, and then retires in another ; on every side, nature's plastic hand is still at work, modelling and remodelling the earth, and making it constantly a fit abode for those '"who dwell upon it.