Although we have not full information concerning the great wave which in May, 1876, swept across the Pacific, and northwards and southwards along the shores of the two Americas, it may be interesting to consider some of the more striking features of this great disturbance of the so-called peaceful ocean, and to compare them with those which have characterized former disturbances of a similar kind. We may thus, perhaps, find some evidence by which an opinion may be formed as to the real seat of subterranean activity in this region.
At the outset it may be necessary to explain why I have asserted somewhat confidently that the tides have nothing whatever to do with this great oceanic wave. It is of course well known to every reader that the highest or spring tides occur always two or three days after new moon and after full moon, the lowest (or rather the tides having least range above and below the mean level) occurring two or three days after the first and third quarters of the lunar month. The sun and moon combine, indeed, to sway the ocean most strongly at full and new, while they pull contrariwise at the first and third quarters; but the full effect of their combined effort is only felt a few days later than when it is made, while the full effect of their opposition16 to each other, in diminishing the range of the oceanic oscillation, is also only felt after two or three days. Thus in May, 1876, the tidal wave had its greatest range on or about May 16, new moon occurring at half-past five on the morning of May 13; and the tidal wave had its least range on or about May 8, the moon passing her third quarter a little after eleven on the morning of May 4. Accordingly the disturbance which affected17 the waters of the Pacific so mightily18 on May 10, occurred two days after the lowest or neap tides, and five days before the highest or spring tides. Manifestly that was not a time when a tidal wave of exceptional height could be expected,180 or, indeed, could possibly occur. Such a wave as actually disturbed the Pacific on that day could not in any case have been produced by tidal action, even though the winds had assisted to their utmost, and all the circumstances which help to make high tides had combined—as the greatest proximity19 of moon to earth, the conjunction of moon and sun near the celestial20 equator, and (of course) the exact coincidence of the time of the tidal disturbance with that when the combined pull of the sun and moon is strongest. As, instead, the sun was nearly eighteen degrees from the equator, the moon more than nine, and as the moon was a full week’s motion from the part of her path where she is nearest to the earth, while, as we have seen, only two days had passed from the time of absolutely lowest tides, it will be seen how utterly21 unable the tidal-wave must have been on the day of the great disturbance to produce the effects presently to be described.
It may seem strange, in dealing22 with the case of a wave which apparently23 had its origin in or near Peru on May 9, to consider the behaviour of a volcano, distant 5000 miles from this region, a week before the disturbance took place. But although the coincidence may possibly have been accidental, yet in endeavouring to ascertain24 the true seat of disturbance we must overlook no evidence, however seemingly remote, which may throw light on that point; and as the sea-wave generated by the disturbance reached very quickly the distant region referred to, it is by no means unlikely that the subterranean excitement which the disturbance relieved may have manifested its effects beforehand at the same remote volcanic25 region. Be this as it may, it is certain that on May 1 the great crater26 of Kilauea, in the island of Hawaii, became active, and on the 4th severe shocks of earthquake were felt at the Volcano House. At three in the afternoon a jet of lava27 was thrown up to a height of about 100 feet, and afterwards some fifty jets came into action. Subsequently jets of steam issued along the line formed by a fissure28 four miles in length181 down the mountain-side. The disturbance lessened29 considerably30 on the 5th, and an observing party examined the crater. They found that a rounded hill, 700 feet in height, and 1400 feet in diameter, had been thrown up on the plain which forms the floor of the crater. Fire and scoria spouted31 up in various places.
Before rejecting utterly the belief that the activity thus exhibited in the Hawaii volcano had its origin in the same subterrene or submarine region as the Peruvian earthquake, we should remember that other regions scarcely less remote have been regarded as forming part of the same Vulcanian district. The violent earthquakes which occurred at New Madrid, in Missouri, in 1812, took place at the same time as the earthquake of Caraccas, the West Indian volcanoes being simultaneously32 active; and earthquakes had been felt in South Carolina for several months before the destruction of Caraccas and La Guayra. Now we have abundant evidence to show that the West Indian volcanoes are connected with the Peruvian and Chilian regions of Vulcanian energy, and the Chilian region is about as far from New Madrid as Arica in Peru from the Sandwich Isles33.
It was not, however, until about half-past eight on the evening of May 9 that the Peruvian earthquake began. A severe shock, lasting34 from four to five minutes, was felt along the entire southern coast, even reaching Antofagasta. The shock was so severe that it was impossible, in many places, to stand upright. It was succeeded by several others of less intensity35.
While the land was thus disturbed, the sea was observed to be gradually receding36, a movement which former experiences have taught the Peruvians to regard with even more terror than the disturbance of the earth itself. The waters which had thus withdrawn37, as if concentrating their energies to leap more fiercely on their prey38, presently returned in a mighty wave, which swept past Callao, travelling southwards with fearful velocity39, while in its train followed wave after wave, until no less than eight had taken182 their part in the work of destruction. At Mollendo the railway was torn up by the sea for a distance of 300 feet. A violent hurricane which set in afterwards from the south prevented all vessels41 from approaching, and unroofed most of the houses in the town. At Arica the people were busily engaged in preparing temporary fortifications to repel42 a threatened assault of the rebel ram43 Huiscar, at the moment when the roar of the earthquake was heard. The shocks here were very numerous, and caused immense damage in the town, the people flying to the Morro for safety. The sea was suddenly perceived to recede44 from the beach, and a wave from ten feet to fifteen feet in height rolled in upon the shore, carrying before it all that it met. Eight times was this assault of the ocean repeated. The earthquake had levelled to the ground a portion of the custom-house, the railway station, the submarine cable office, the hotel, the British Consulate45, the steamship46 agency, and many private dwellings47. Owing to the early hour of the evening, and the excitement attendant on the proposed attack of the Huiscar, every one was out and stirring; but the only loss of life which was reported was that of three little children who were overtaken by the water. The progress of the wave was only stopped at the foot of the hill on which the church stands, which point is further inland than that reached in August, 1868. Four miles of the embankment of the railway were swept away like sand before the wind. Locomotives, cars, and rails, were hurled48 about by the sea like so many playthings, and left in a tumbled mass of rubbish.
The account proceeds to say that the United States steamer Waters, stranded49 by the bore of 1868, was lifted up bodily by the wave at Arica, and floated two miles north of her former position. The reference is no doubt to the double-ender Watertree, not stranded by a bore (a term utterly inapplicable to any kind of sea-wave at Arica, where there is no large river), but carried in by the great wave which followed the earthquake of August 13. The description of the wave at Arica on that occasion should be183 compared with that of the wave of May, 1876. About twenty minutes after the first earth shock, the sea was seen to retire, as if about to leave the shores wholly dry; but presently its waters returned with tremendous force. A mighty wave, whose length seemed immeasurable, was seen advancing like a dark wall upon the unfortunate town, a large part of which was overwhelmed by it. Two ships, the Peruvian corvette America, and the American double-ender Watertree, were carried nearly half a mile to the north of Arica, beyond the railroad which runs to Tacna, and there left stranded high and dry. As the English vice50-consul at Arica estimated the height of this enormous wave at fully51 fifty feet, it would not seem that the account of the wave of May, 1876, has been exaggerated, for a much less height is, as we have seen, attributed to it, though, as it carried the Watertree still further inland, it must have been higher. The small loss of life can be easily understood when we consider that the earthquake was not followed instantly by the sea-wave. Warned by the experience of the earthquake of 1868, which most of them must have remembered, the inhabitants sought safety on the higher grounds until the great wave and its successors had flowed in. We read that the damage done was greater than that caused by the previous calamity52, the new buildings erected53 since 1868 being of a more costly54 and substantial class. Merchandise from the custom-house and stores was carried by the water to a point on the beach five miles distant.
At Iquique, in 1868, the great wave was estimated at fifty feet in height. We are told that it was black with the mud and slime of the sea bottom. “Those who witnessed its progress from the upper balconies of their houses, and presently saw its black mass rushing close beneath their feet, looked on their safety as a miracle. Many buildings were, indeed, washed away, and in the low-lying parts of the town there was a terrible loss of life.” In May, 1876, the greatest mischief55 at Iquique would seem to have been caused by the earthquake, not by the sea-wave, though184 this also was destructive in its own way. “Iquique,” we are told, “is in ruins. The movement was experienced there at the same time and with the same force [as at Arica]. Its duration was exactly four minutes and a third. It proceeded from the south-east, exactly from the direction of Ilaga.” The houses built of wood and cane40 tumbled down at the first attacks, lamps were broken, and the burning oil spread over and set fire to the ruins. Three companies of firemen, German, Italian, and Peruvian, were instantly at their posts, although it was difficult to maintain an upright position, shock following shock with dreadful rapidity. Nearly 400,000 quintals of nitrate in the stores at Iquique and the adjacent ports of Molle and Pisagua were destroyed. The British barque Caprera and a German barque sank, and all the coasting craft and small boats in the harbour were broken to pieces and drifted about in every direction.
At Chanavaya, a small town at the guano-loading dép?t known as Pabellon de Pica, only two houses were left standing56 out of four hundred. Here the earthquake shock was specially57 severe. In some places the earth opened in crevices58 seventeen yards deep and the whole surface of the ground was changed.
At Punta de Eobos two vessels were lost, and fourteen ships more or less damaged, by the wave. Antofagasta, Mexillones, Tocopilla, and Cobigo, on the Bolivian coast, suffered simultaneously from the earthquake and the sea-wave. The sea completely swept the business portion of Antofagasta during four hours. Here a singular phenomenon was noticed. For some time the atmosphere was illuminated59 with a ruddy glow. It was supposed that this light came from the volcano of San Pedro de Atacama, a few leagues inland from Antofagasta. A somewhat similar phenomenon was noticed at Tacna during the earthquake of August, 1868. About three hours after the earthquake an intensely brilliant light made its appearance above the neighbouring mountains. It lasted fully half an hour, and was ascribed to the eruption60 of some as yet unknown volcano.
185 As to the height of the great wave along this part of the shore-line of South America, the accounts vary. According to those which are best authenticated61, it would seem as though the wave exceeded considerably in height that which flowed along the Peruvian, Bolivian, and Chilian shores in August, 1868. At Huaniles the wave was estimated at sixty feet in height, at Mexillones, where the wave, as it passed southwards, ran into Mexillones Bay, it reached a height of sixty-five feet. Two-thirds of the town were completely obliterated62, wharves63, railway stations, distilleries, etc., all swallowed up by the sea.
The shipping64 along the Peruvian and Bolivian coast suffered terribly. The list of vessels lost or badly injured at Pabellon de Pica alone, reads like the list of a fleet.
I have been particular in thus describing the effects produced by the earthquake and sea-wave on the shores of South America, in order that the reader may recognize in the disturbance produced there the real origin of the great wave which a few hours later reached the Sandwich Isles, 5000 miles away. Doubt has been entertained respecting the possibility of a wave, other than the tidal-wave, being transmitted right across the Pacific. Although in August, 1868, the course of the great wave which swept from some region near Peru, not only across the Pacific, but in all directions over the entire ocean, could be clearly traced, there were some who considered the connection between the oceanic phenomena and the Peruvian earthquake a mere65 coincidence. It is on this account perhaps chiefly that the evidence obtained in May, 1876, is most important. It is interesting, indeed, as showing how tremendous was the disturbance which the earth’s frame must then have undergone. It would have been possible, however, had we no other evidence, for some to have maintained that the wave which came in upon the shores of the Sandwich Isles a few hours after the earthquake and sea disturbance in South America was in reality an entirely66 independent phenomenon. But when we compare the events which happened in May, 1876,186 with those of August, 1868, and perceive their exact similarity, we can no longer reasonably entertain any doubt of the really stupendous fact that the throes of the earth in and near Peru are of sufficient energy to send oceanic waves right across the Pacific,—waves, too, of such enormous height at starting, that, after travelling with necessarily diminishing height the whole way to Hawaii, they still rose and fell through thirty-six feet The real significance of this amazing oceanic disturbance is exemplified by the wave circles which spread around the spot where a stone has fallen into a smooth lake. We know how, as the circles widen, the height of the wave grows less and less, until, at no great distance from the centre of disturbance, the wave can no longer be discerned, so slight is the slope of its advancing and following faces. How tremendous, then, must have been the upheaval of the bed of ocean by which wave-circles were sent across the Pacific, retaining, after travelling 5000 miles from the centre of disturbance, the height of a two-storied house! In 1868, indeed, we know that the wave travelled very much further, reaching the shores of Japan, of New Zealand, and of Australia, even if it did not make its way through the East Indian Archipelago to the Indian Ocean, as some observations seem to show. Although no news has been received which would justify67 us in believing that the wave of May, 1876, produced corresponding effects at such great distances from the centre of disturbance, it must be remembered that the dimensions of the wave when it reached the Sandwich Isles fell far short of those of the great wave of August 13–14, 1868.
It will be well to make a direct comparison between the waves of May, 1876, and August, 1868, in this respect, as also with regard to the rate at which they would seem to have traversed the distance between Peru and Hawaii. On this last point, however, it must be noted68 that we cannot form an exact opinion until we have ascertained69 the real region of Vulcanian disturbance on each occasion. It is possible that a careful comparison of times, and of the direction in which the wave front advanced upon different shores, might serve187 to show where this region lay. I should not be greatly surprised to learn that it was far from the continent of South America.
The great wave reached the Sandwich Isles between four and five on the morning of May 10, corresponding to about five hours later of Peruvian time. An oscillation only was first observed at Hilo, on the east coast of the great southern island of Hawaii, the wave itself not reaching the village till about a quarter before five. The greatest difference between the crest70 and trough of the wave was found to be thirty-six feet here; but at the opposite side of the island, in Kealakekua Bay (where Captain Cook was killed), amounted only to thirty feet. In other places the difference was much less, being in some only three feet, a circumstance doubtless due to interference, waves which have reached the same spot along different courses chancing so to arrive that the crest of one corresponded with the trough of the other, so that the resulting wave was only the difference of the two. We must explain, however, in the same way, the highest waves of thirty-six to forty feet, which were doubtless due to similar interference, crest agreeing with crest and trough with trough, so that the resulting wave was the sum of the two which had been divided, and had reached the same spot along different courses. It would follow that the higher of the two waves was about twenty-one feet high, the lower about eighteen feet high; but as some height would be lost in the encounter with the shore-line, wherever it lay, on which the waves divided, we may fairly assume that in the open ocean, before reaching the Sandwich group, the wave had a height of nearly thirty feet from trough to crest. We read, in accordance with this explanation, that “the regurgitations of the sea were violent and complex, and continued through the day.”
The wave, regarded as a whole, seems to have reached all the islands at the same time. Since this has not been contradicted by later accounts, we are compelled to conclude that the wave reached the group with its front parallel to the188 length of the group, so that it must have come (arriving as it did from the side towards which Hilo lies) from the north-east It was, then, not the direct wave from Peru, but the wave reflected from the shores of California, which produced the most marked effects. We can understand well, this being so, that the regurgitations of the sea were complex. Any one who has watched the inflow of waves on a beach so lying within an angle of the line that while one set of waves comes straight in from the sea, another thwart71 set comes from the shore forming the other side of the angle, will understand how such waves differ from a set of ordinary rollers. The crests72 of the two sets form a sort of network, ever changing as each set rolls on; and considering any one of the four-cornered meshes73 of this wave-net, the observer will notice that while the middle of the raised sides rises little above the surrounding level, because here the crests of one set cross the troughs of the other, the corners of each quadrangle are higher than they would be in either set taken separately, while the middle of the four-cornered space is correspondingly depressed74. The reason is that at the corners of the wave-net crests join with crests to raise the water surface, while in the middle of the net (not the middle of the sides, but the middle of the space enclosed by the four sides) trough joins with trough to depress the water surface.24
We must take into account the circumstance that the wave which reached Hawaii in May, 1876, was probably reflected from the Californian coast, when we endeavour to determine the rate at which the sea disturbance was propagated across189 the Atlantic. The direct wave would have come sooner, and may have escaped notice because arriving in the night-time, as it would necessarily have done if a wave which travelled to California, and thence, after reflection, to the Sandwich group arrived there at a quarter before five in the morning following the Peruvian earthquake. We shall be better able to form an opinion on this point after considering what happened in August, 1868.
The earth-throe on that occasion was felt in Peru about five minutes past five on the evening of August 13. Twelve hours later, or shortly before midnight, August 13, Sandwich Island time (corresponding to 5 p.m., August 14, Peruvian time), the sea round the group of the Sandwich Isles rose in a surprising manner, “insomuch that many thought the islands were sinking, and would shortly subside75 altogether beneath the waves. Some of the smaller islands were for a time completely submerged. Before long, however, the sea fell again, and as it did so the observers found it impossible to resist the impression that the islands were rising bodily out of the water. For no less than three days this strange oscillation of the sea continued to be experienced, the most remarkable76 ebbs77 and floods being noticed at Honolulu, on the island of Woahoo.”
The distance between Honolulu and Arica is about 6300 statute78 miles; so that, if the wave travelled directly from the shores of Peru to the Sandwich Isles, it must have advanced at an average rate of about 525 miles an hour (about 450 knots an hour). This is nearly half the rate at which the earth’s surface near the equator is carried round by the earth’s rotation79, or is about the rate at which parts in latitude80 62 or 63 degrees north are carried round by rotation; so that the motion of the great wave in 1868 was fairly comparable with one of the movements which we are accustomed to regard as cosmical. I shall presently have something more to say on this point.
Now in May, 1876, as we have seen, the wave reached Hawaii at about a quarter to five in the morning, corresponding190 to about ten, Peruvian time. Since, then, the earthquake was felt in Peru at half-past eight on the previous evening, it follows that the wave, if it travelled directly from Peru, must have taken about 13? hours—or an hour and a half longer, in travelling from Peru to the Sandwich Isles, than it took in August, 1868. This is unlikely, because ocean-waves travel nearly at the same rate in the same parts of the ocean, whatever their dimensions, so only that they are large. We have, then, in the difference of time occupied by the wave in May, 1876, and in August, 1868, in reaching Hawaii, some confirmation81 of the result to which we were led by the arrival of the wave simultaneously at all the islands of the Sandwich group—the inference, namely, that the observed wave had reached these islands after reflection from the Californian shore-line. As the hour when the direct wave probably reached Hawaii was about a quarter past three in the morning, when not only was it night-time but also a time when few would be awake to notice the rise and fall of the sea, it seems not at all improbable that the direct wave escaped notice, and that the wave actually observed was the reflected wave from California. The direction, also, in which the oscillation was first observed corresponds well with this explanation.
It is clear that the wave which traversed the Pacific in May, 1876, was somewhat inferior in size to that of August, 1868, which therefore still deserves to be called (as I then called it) the greatest sea-wave ever known. The earthquake, indeed, which preceded the oceanic disturbance of 1868 was far more destructive than that of May, 1876, and the waves which came in upon the Peruvian and Bolivian shores were larger. Nevertheless, the wave of May, 1876, was not so far inferior to that of August, 1868, but that its course could be traced athwart the entire extent of the Pacific Ocean.
When we consider the characteristic features of the Peruvian and Chilian earthquakes, and especially when we note how wide is the extent of the region over which their191 action is felt in one way or another, it can scarcely be doubted that the earth’s Vulcanian energies are at present more actively82 at work throughout that region than in any other. There is nothing so remarkable, one may even say so stupendous, in the history of subterranean disturbance as the alternation of mighty earth-throes by which, at one time, the whole of the Chilian Andes seem disturbed and anon the whole of the Peruvian Andes. In Chili scarcely a year ever passes without earthquakes, and the same may be said of Peru; but so far as great earthquakes are concerned the activity of the Peruvian region seems to synchronize83 with the comparative quiescence84 of the Chilian region, and vice versa. Thus, in 1797, the terrible earthquake occurred which is known as the earthquake of Riobamba, which affected the entire Peruvian earthquake region. Thirty years later a series of tremendous throes shook the whole of Chili, permanently85 elevating its long line of coast to the height of several feet. During the last twelve years the Peruvian region has in turn been disturbed by great earthquakes. It should be added that between Chili and Peru there is a region about five hundred miles in length in which scarcely any volcanic action has been observed. And singularly enough, “this very portion of the Andes, to which one would imagine that the Peruvians and Chilians would fly as to a region of safety, is the part most thinly inhabited; insomuch that, as Von Buch observes, it is in some places entirely deserted86.”
One can readily understand that this enormous double region of earthquakes, whose oscillations on either side of the central region of comparative rest may be compared to the swaying of a mighty see-saw on either side of its point of support, should be capable of giving birth to throes propelling sea-waves across the Pacific Ocean. The throe actually experienced at any given place is relatively87 but an insignificant88 phenomenon: it is the disturbance of the entire region over which the throe is felt which must be considered in attempting to estimate the energy of the disturbing cause. The region shaken by the earthquake of 1868, for instance,192 was equal to at least a fourth of Europe, and probably to fully one-half. From Quito southwards as far as Iquique—or along a full third part of the length of the South American Andes—the shock produced destructive effects. It was also distinctly felt far to the north of Quito, far to the south of Iquique, and inland to enormous distances. The disturbing forces which thus shook 1,000,000 square miles of the earth’s surface must have been of almost inconceivable energy. If directed entirely to the upheaval of a land region no larger than England, those forces would have sufficed to have destroyed utterly every city, town, and village within such a region; if directed entirely to the upheaval of an oceanic region, they would have been capable of raising a wave which would have been felt on every shore-line of the whole earth. Divided even between the ocean on the one side and a land region larger than Russia in Europe on the other, those Vulcanian forces shook the whole of the land region, and sent athwart the largest of our earth’s oceans a wave which ran in upon shores 10,000 miles from the centre of disturbance with a crest thirty feet high. Forces such as these may fairly be regarded as cosmical; they show unmistakably that the earth has by no means settled down into that condition of repose89 in which some geologists still believe. We may ask with the late Sir Charles Lyell whether, after contemplating90 the tremendous energy thus displayed by the earth, any geologist7 will continue to assert that the changes of relative level of land and sea, so common in former ages of the world, have now ceased? and agree with him that if, in the face of such evidence, a geologist persists in maintaining this favourite dogma, it would be vain to hope, by accumulating proofs of similar convulsions during a series of ages, to shake the tenacity91 of his conviction—
“Si fractus illabatur orbis, Impavidum ferient ruin?.”
But there is one aspect in which such mighty sea-waves as, in 1868 and again in May, 1876, have swept over the surface of our terrestrial oceans, remains92 yet to be considered.
193 The oceans and continents of our earth must be clearly discernible from her nearer neighbours among the planets—from Venus and Mercury on the inner side of her path around the sun, and from Mars (though under less favourable93 conditions) from the outer side. When we consider, indeed, that the lands and seas of Mars can be clearly discerned with telescopic aid from our earth at a distance of forty millions of miles, we perceive that our earth, seen from Venus at little more than half this distance, must present a very interesting appearance. Enlarged, owing to greater proximity, nearly fourfold, having a diameter nearly twice as great as that of Mars, so that at the same distance her disc would seem more than three times as large, more brightly illuminated by the sun in the proportion of about five to two, she would shine with a lustre94 exceeding that of Mars, when in full brightness in the midnight sky, about thirty times; and all her features would of course be seen with correspondingly increased distinctness. Moreover, the oceans of our earth are so much larger in relative extent than those of Mars, covering nearly three-fourths instead of barely one-half of the surface of the world they belong to, that they would appeal as far more marked and characteristic features than the seas and lakes of Mars. When the Pacific Ocean, indeed, occupies centrally the disc of the earth which at the moment is turned towards any planet, nearly the whole of that disc must appear to be covered by the ocean. Under such circumstances the passage of a wide-spreading series of waves over the Pacific, at the rate of about 500 miles an hour, is a phenomenon which could scarcely fail to be discernible from Venus or Mercury, if either planet chanced to be favourably95 placed for the observation of the earth—always supposing there were observers in Mercury or Venus, and that these observers were provided with powerful telescopes.
It must be remembered that the waves which spread over the Pacific on August 13–14, 1868, and again on May 9–10, 1876, were not only of enormous range in length (measured along crest or trough), but also of enormous194 breadth (measured from crest to crest, or from trough to trough). Were it otherwise, indeed, the progress of a wave forty or fifty feet high (at starting, and thirty-five feet high after travelling 6000 miles), at the rate of 500 miles per hour, must have proved destructive to ships in the open ocean as well as along the shore-line. Suppose, for instance, the breadth of the wave from crest to crest one mile, then, in passing under a ship at the rate of 500 miles per hour, the wave would raise the ship from trough to crest—that is, through a height of forty feet—in one-thousandth part of an hour (for the distance from trough to crest is but half the breadth of the wave), or in less than four seconds, lowering it again in the same short interval96 of time, lifting and lowering it at the same rate several successive times. The velocity with which the ship would travel upwards97 and downwards98 would be greatest when she was midway in her ascent99 and descent, and would then be equal to about the velocity with which a body strikes the ground after falling from a height of four yards. It is hardly necessary to say that small vessels subjected to such tossing as this would inevitably100 be swamped. On even the largest ships the effect of such motion would be most unpleasantly obvious. Now, as a matter of fact, the passage of the great sea-wave in 1868 was not noticed at all on board ships in open sea. Even within sight of the shore of Peru, where the oscillation of the sea was most marked, the motion was such that its effects were referred to the shore. We are told that observers on the deck of a United States’ war steamer distinctly saw the “peaks of the mountains in the chain of the Cordilleras wave to and fro like reeds in a storm;” the fact really being that the deck on which they stood was swayed to and fro. This, too, was in a part of the sea where the great wave had not attained101 its open sea form, but was a rolling wave, because of the shallowness of the water. In the open sea, we read that the passage of the great sea-wave was no more noticed than is the passage of the tidal-wave itself. “Among the hundreds of ships which were sailing upon the Pacific when its length and breadth195 were traversed by the great sea-wave, there was not one in which any unusual motion was perceived.” The inference is clear, that the slope of the advancing and following faces of the great wave was very much less than in the case above imagined; in other words, that the breadth of the wave greatly exceeded one mile—amounting, in fact, to many miles.
Where the interval between the passage of successive wave-crests was noted, we can tell the actual breadth of the wave. Thus, at the Samoan Isles, in 1868, the crests succeeded each other at intervals102 of sixteen minutes, corresponding to eight minutes between crest and trough. But we have seen, that if the waves were one mile in breadth, the corresponding interval would be only four seconds, or only one 120th part of eight minutes: it follows, then, that the breadth of the great wave, where it reached the Samoan Isles in 1868, was about 120 miles.
Now a wave extending right athwart the Pacific Ocean, and having a cross breadth of more than 120 miles, would be discernible as a marked feature of the disc of our earth, seen under the conditions described above, either from Mercury or Venus. It is true that the slope of the wave’s advancing and following surfaces would be but slight, yet the difference of the illumination under the sun’s rays would be recognizable. Then, also, it is to be remembered that there was not merely a single wave, but a succession of many waves. These travelled also with enormous velocity; and though at the distance of even the nearest planet, the apparent motion of the great wave, swift though it was in reality, would be so far reduced that it would have to be estimated rather than actually seen, yet there would be no difficulty in thus perceiving it with the mind’s eye. The rate of motion indeed would almost be exactly the same as that of the equatorial part of the surface of Mars, in consequence of the planet’s rotation; and this (as is well known to telescopists), though not discernible directly, produces, even in a few minutes, changes which a good eye can clearly recognize.196 We can scarcely doubt then that if our earth were so situated103 at any time when one of the great waves generated by Peruvian earthquakes in traversing the Pacific, that the hemisphere containing this ocean were turned fully illuminated towards Venus (favourably placed for observing her), the disturbance of the Pacific could be observed and measured by telescopists on that planet.
Unfortunately there is little chance that terrestrial observers will ever be able to watch the progress of great waves athwart the oceans of Mars, and still less that any disturbance of the frame of Venus should become discernible to us by its effects. We can scarce even be assured that there are lands and seas on Venus, so far as direct observation is concerned, so unfavourably is she always placed for observation; and though we see Mars under much more favourable conditions, his seas are too small and would seem to be too shallow (compared with our own) for great waves to traverse them such as could be discerned from the earth.
Yet it is well to remember the possibility that changes may at times take place in the nearer planets—the terrestrial planets, as they are commonly called, Mars, Venus, and Mercury—such as telescopic observation under favourable conditions might detect. Telescopists have, indeed, described apparent changes, lasting only for a short time, in the appearance of one of these planets, Mars, which may fairly be attributed to disturbances affecting its surface in no greater degree than the great Peruvian earthquakes have affected for a time the surface of our earth. For instance, the American astronomer104 Mitchel says that on the night of July 12, 1845, bright polar snows of Mars exhibited an appearance never noticed at any preceding or succeeding observation. In the very centre of the white surface appeared a dark spot, which retained its position during several hours: on the following evening not a trace of the spot could be seen. Again the same observer says that on the evening of August 30, 1845, he observed for the first time a small bright spot, nearly or quite round, projecting out of the197 lower side of the polar spot. “In the early part of the evening,” he says, “the small bright spot seemed to be partly buried in the large one. After the lapse105 of an hour or more my attention was again directed to the planet, when I was astonished to find a manifest change in the position of the small bright spot. It had apparently separated from the large spot, and the edges alone of the two were now in contact, whereas when first seen they overlapped106 by an amount quite equal to one-third of the diameter of the small one. This, however, was merely an optical phenomenon, for on the next evening the spots went through the same apparent changes as the planet went through the corresponding part of its rotation. But it showed the spots to be real ice masses. The strange part of the story is that in the course of a few days the smaller spot, which must have been a mass of snow and ice as large as Novaia Zemlia, gradually disappeared. Probably some great shock had separated an enormous field of ice from the polar snows, and it had eventually been broken up and its fragments carried away from the Arctic regions by currents in the Martian oceans. It appears to me that the study of our own earth, and of the changes and occasional convulsions which affect its surface, gives to the observation of such phenomena as I have just described a new interest. Or rather, perhaps, it is not too much to say that the telescopic observations of the planets derive107 their only real interest from such considerations.
I may note in conclusion, that while on the one hand we cannot doubt that the earth is slowly parting with its internal heat, and thus losing century by century a portion of its Vulcanian energy, such phenomena as the Peruvian earthquakes show that the loss of energy is taking place so slowly that the diminution108 during many ages is almost imperceptible. As I have elsewhere 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 and to types, we recognize the great work which the198 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 scooped109 out; old shore-lines shift their place, old soundings vary; the sea advances in one place and retires in another; on every side nature’s plastic hand is still at work, modelling and remodelling110 the earth, and making it constantly a fit abode111 for those who dwell upon it.”
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1
upheaval
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| n.胀起，(地壳)的隆起；剧变，动乱 | |
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chili
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| n.辣椒 | |
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celebrated
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| adj.有名的，声誉卓著的 | |
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subterranean
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| adj.地下的，地表下的 | |
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upheavals
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| 突然的巨变( upheaval的名词复数 )； 大动荡； 大变动； 胀起 | |
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geologists
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| 地质学家，地质学者( geologist的名词复数 ) | |
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geologist
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| n.地质学家 | |
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geographers
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| 地理学家( geographer的名词复数 ) | |
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disturbance
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| n.动乱，骚动；打扰，干扰；(身心)失调 | |
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disturbances
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| n.骚乱( disturbance的名词复数 )；打扰；困扰；障碍 | |
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mighty
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| adj.强有力的；巨大的 | |
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imprisoned
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| 下狱，监禁( imprison的过去式和过去分词 ) | |
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apex
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| n.顶点，最高点 | |
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vent
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| n.通风口，排放口；开衩；vt.表达，发泄 | |
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phenomena
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| n.现象 | |
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opposition
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| n.反对，敌对 | |
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affected
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| adj.不自然的，假装的 | |
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mightily
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| ad.强烈地；非常地 | |
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proximity
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| n.接近，邻近 | |
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celestial
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| adj.天体的；天上的 | |
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utterly
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| adv.完全地，绝对地 | |
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dealing
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| n.经商方法，待人态度 | |
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apparently
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| adv.显然地；表面上，似乎 | |
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ascertain
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| vt.发现，确定，查明，弄清 | |
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volcanic
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| adj.火山的；象火山的；由火山引起的 | |
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crater
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| n.火山口，弹坑 | |
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lava
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| n.熔岩，火山岩 | |
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fissure
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| n.裂缝；裂伤 | |
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lessened
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| 减少的，减弱的 | |
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considerably
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| adv.极大地；相当大地；在很大程度上 | |
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spouted
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| adj.装有嘴的v.（指液体）喷出( spout的过去式和过去分词 )；滔滔不绝地讲；喋喋不休地说；喷水 | |
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simultaneously
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| adv.同时发生地，同时进行地 | |
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isles
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| 岛( isle的名词复数 ) | |
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lasting
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| adj.永久的，永恒的；vbl.持续，维持 | |
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intensity
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| n.强烈，剧烈；强度；烈度 | |
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receding
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| v.逐渐远离( recede的现在分词 )；向后倾斜；自原处后退或避开别人的注视；尤指问题 | |
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withdrawn
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| vt.收回；使退出；vi.撤退，退出 | |
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prey
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| n.被掠食者，牺牲者，掠食；v.捕食，掠夺，折磨 | |
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velocity
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| n.速度，速率 | |
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cane
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| n.手杖，细长的茎，藤条；v.以杖击，以藤编制的 | |
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vessels
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| n.血管( vessel的名词复数 )；船；容器；（具有特殊品质或接受特殊品质的）人 | |
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42
repel
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| v.击退，抵制，拒绝，排斥 | |
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ram
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| (random access memory)随机存取存储器 | |
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recede
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| vi.退(去)，渐渐远去；向后倾斜，缩进 | |
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consulate
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| n.领事馆 | |
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46
steamship
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| n.汽船，轮船 | |
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dwellings
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| n.住处，处所( dwelling的名词复数 ) | |
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48
hurled
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| v.猛投，用力掷( hurl的过去式和过去分词 )；大声叫骂 | |
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stranded
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| a.搁浅的，进退两难的 | |
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vice
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| n.坏事；恶习；[pl.]台钳，老虎钳；adj.副的 | |
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51
fully
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| adv.完全地，全部地，彻底地；充分地 | |
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52
calamity
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| n.灾害，祸患，不幸事件 | |
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53
ERECTED
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| adj. 直立的，竖立的，笔直的 vt. 使 ... 直立，建立 | |
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54
costly
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| adj.昂贵的，价值高的，豪华的 | |
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55
mischief
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| n.损害，伤害，危害；恶作剧，捣蛋，胡闹 | |
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56
standing
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| n.持续，地位；adj.永久的，不动的，直立的，不流动的 | |
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specially
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| adv.特定地；特殊地；明确地 | |
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crevices
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| n.（尤指岩石的）裂缝，缺口( crevice的名词复数 ) | |
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59
illuminated
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| adj.被照明的；受启迪的 | |
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60
eruption
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| n.火山爆发；（战争等）爆发；（疾病等）发作 | |
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61
authenticated
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| v.证明是真实的、可靠的或有效的( authenticate的过去式和过去分词 )；鉴定，使生效 | |
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62
obliterated
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| v.除去( obliterate的过去式和过去分词 )；涂去；擦掉；彻底破坏或毁灭 | |
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wharves
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| n.码头，停泊处( wharf的名词复数 ) | |
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shipping
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| n.船运（发货，运输，乘船） | |
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mere
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| adj.纯粹的；仅仅，只不过 | |
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entirely
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| ad.全部地，完整地；完全地，彻底地 | |
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justify
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| vt.证明…正当(或有理)，为…辩护 | |
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noted
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| adj.著名的，知名的 | |
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ascertained
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| v.弄清，确定，查明( ascertain的过去式和过去分词 ) | |
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crest
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| n.顶点；饰章；羽冠；vt.达到顶点；vi.形成浪尖 | |
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71
thwart
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| v.阻挠，妨碍，反对；adj.横(断的) | |
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crests
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| v.到达山顶（或浪峰）( crest的第三人称单数 )；到达洪峰，达到顶点 | |
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73
meshes
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| 网孔( mesh的名词复数 )； 网状物； 陷阱； 困境 | |
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depressed
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| adj.沮丧的，抑郁的，不景气的，萧条的 | |
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subside
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| vi.平静，平息；下沉，塌陷，沉降 | |
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76
remarkable
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| adj.显著的，异常的，非凡的，值得注意的 | |
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ebbs
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| 退潮( ebb的名词复数 )； 落潮； 衰退 | |
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statute
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| n.成文法，法令，法规；章程，规则，条例 | |
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rotation
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| n.旋转；循环，轮流 | |
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latitude
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| n.纬度，行动或言论的自由(范围)，(pl.)地区 | |
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81
confirmation
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| n.证实，确认，批准 | |
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actively
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| adv.积极地，勤奋地 | |
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83
synchronize
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| v.使同步 [=synchronise] | |
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84
quiescence
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| n.静止 | |
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85
permanently
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| adv.永恒地，永久地，固定不变地 | |
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86
deserted
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| adj.荒芜的，荒废的，无人的，被遗弃的 | |
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relatively
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| adv.比较...地，相对地 | |
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insignificant
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| adj.无关紧要的，可忽略的，无意义的 | |
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repose
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| v.(使)休息；n.安息 | |
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contemplating
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| 深思，细想，仔细考虑( contemplate的现在分词 )； 注视，凝视； 考虑接受（发生某事的可能性）； 深思熟虑，沉思，苦思冥想 | |
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91
tenacity
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| n.坚韧 | |
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92
remains
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| n.剩余物，残留物；遗体，遗迹 | |
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93
favourable
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| adj.赞成的，称赞的，有利的，良好的，顺利的 | |
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lustre
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| n.光亮，光泽；荣誉 | |
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favourably
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| adv. 善意地，赞成地 =favorably | |
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interval
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| n.间隔，间距；幕间休息，中场休息 | |
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upwards
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| adv.向上，在更高处...以上 | |
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98
downwards
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| adj./adv.向下的（地），下行的（地） | |
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99
ascent
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| n.(声望或地位)提高；上升，升高；登高 | |
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inevitably
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| adv.不可避免地；必然发生地 | |
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101
attained
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| （通常经过努力）实现( attain的过去式和过去分词 )； 达到； 获得； 达到（某年龄、水平、状况） | |
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102
intervals
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| n.[军事]间隔( interval的名词复数 )；间隔时间；[数学]区间；（戏剧、电影或音乐会的）幕间休息 | |
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103
situated
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| adj.坐落在...的，处于某种境地的 | |
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astronomer
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| n.天文学家 | |
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105
lapse
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| n.过失，流逝，失效，抛弃信仰，间隔；vi.堕落，停止，失效，流逝；vt.使失效 | |
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106
overlapped
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| _adj.重叠的v.部分重叠( overlap的过去式和过去分词 )；（物体）部份重叠；交叠；（时间上）部份重叠 | |
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107
derive
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| v.取得；导出；引申；来自；源自；出自 | |
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108
diminution
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| n.减少；变小 | |
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109
scooped
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| v.抢先报道( scoop的过去式和过去分词 )；（敏捷地）抱起；抢先获得；用铲[勺]等挖（洞等） | |
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110
remodelling
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| v.改变…的结构[形状]( remodel的现在分词 ) | |
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abode
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| n.住处，住所 | |
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