CHAPTER VIII.

THE OCEAN AND SOME OF ITS PHENOMENA.

The Saltness of the Sea—Its Composition—Tons of Silver in the Ocean—Currents and their Causes—The Great Gulf Stream—Its Characteristics—A Triumph of Science—The Tides—The Highest Known Tides and Waves—Whirlpools—The Maelström—A Norwegian Description—Edgar Allan Poe and his Story—Rescued from the Vortex—The “Souffleur” at the Mauritius—The Colour of the Sea—Its Causes—The Phosphorescence of the Ocean—Fields of Silver—Principally Caused by Animal Life.

Many features and phenomena of the ocean have been incidentally noted in the foregoing pages; but there are points, hitherto untouched, which deserve our attention.

Its saltness is due, not merely to the presence of chloride of sodium, or what we call common salt, but to a large number of other minerals, including the chlorides of magnesium and potassium, the sulphates of magnesia and lime, carbonate of lime, sulphuretted hydrogen, bromide of magnesia, hydrochlorate of ammonia, iodine, iron, copper, and even silver, varying in proportion according to locality. The copper plates of a ship examined at Valparaiso showed unmistakable traces of silver deposits. Calculations have been made showing that the ocean contains 2,000,000 tons of silver. In 1,000 grains of sea‐water there are thirty‐eight grains of these ingredients and some little organic matter. The saltness of the sea is generally greater towards the poles, but to this statement there are exceptions. In parts of the Irish Channel the water contains salts equal to the fortieth of its weight, the saline matter rising to one‐sixteenth of its weight off the coast of Spain. In many places the ocean is less salt at the surface than at the bottom. Its saltness increases its density and its buoyancy.

Maury, a recognised authority, finds in the saline properties of the sea one of the principal forces from which the currents in the ocean proceed. “The brine of the ocean,” says he, “is the ley of the earth; from it the sea derives dynamical powers, and the currents their main strength.” Let us suppose a long tank or, say, swimming‐bath, divided in the middle by a water‐tight wall, on one side of which should be fresh and on the other salt water, at equal levels. It is obvious that were the division removed the waters would not stand side by side as before, for the denser water would have a tendency not merely to mingle with the lighter, but to form a current _under_ it. So salt waters of different densities.

“The ocean,” says Figuier, “is a scene of unceasing agitation; ‘its vast surface rises and falls,’ to use the image suggested by Schleiden, ‘as if it were gifted with a gentle power of respiration; its movements, gentle or powerful, slow or rapid, are all determined by differences of temperature.’” Heat increases its volume, and therefore lightens it; cold increases its density, and it will naturally descend. These are, then, among the obvious reasons of its currents. The duration and force of winds and the tides are both disturbing influences. Such an oceanic marvel as the great _Gulf Stream_ could only be explained after a careful study of all the operating causes of its existence. Dr. Maury has well described it. He says:—“There is a river in the bosom of the ocean: in the severest droughts it never fails, and in the mightiest floods it never overflows; its banks and its bottom are of cold water, while its current is of warm; it takes its rise in the Gulf of Mexico, and empties itself into the Arctic seas; this mighty river is the Gulf Stream. In no other part of the world is there such a majestic flow of water; its current is more rapid than the Amazon, more impetuous than the Mississippi, and its volume is more than a thousand times greater.” This great current of water particularly influences the climates of Northern Europe, and especially those of Britain and Ireland.

The Gulf Stream, as it issues from the Florida Channel, has a breadth of thirty‐four miles, a depth of 2,200 feet, and moves at the rate of four and a half miles an hour. “Midway in the Atlantic, in the triangular space between the Azores, Canaries, and Cape de Verd Islands, is the great Sargassum Sea, covering an area equal to the Mississippi Valley; it is so thickly matted over with the Gulf weed (_Sargassum bacciferum_) that the speed of vessels passing through it is actually retarded, and to the companions of Columbus it seemed to mark the limits of navigation: they became alarmed. To the eye, at a little distance, it seemed sufficiently substantial to walk upon.” The difference of temperature between the Gulf Stream and the waters it traverses constantly gives birth to tempests and cyclones. In 1780 a terrible storm ravaged the Antilles, in which 20,000 persons perished. The ocean quitted its bed, and inundated whole cities; the trunks of great trees and large parts of buildings were tossed wildly in the air. Numerous catastrophes of this kind have earned the Gulf Stream the title of the “King of the Tempests.” So well had Maury studied the Gulf Stream and its storms, that he was enabled to point out the exact position of a vessel overtaken by a terrible gale. “In the month of December, 1859,” says Figuier, “the American packet _San Francisco_ was employed as a transport to convey a regiment to California. It was overtaken by one of these sudden storms, which placed the ship and its freight in a most dangerous position—a single wave, which swept the deck, tore out the masts, stopped the engines, and washed overboard 129 persons, officers, and soldiers. From that moment the unfortunate steamer floated upon the waters, a waif abandoned to the fury of the wind. The day after the disaster the _San Francisco_ was seen in this desperate situation by a ship, which reached New York, although unable to assist her. Another ship met her some days after, but, like the other, could render no assistance. When the report reached New York two steamers were despatched to her assistance; but in what direction were they to go? what part of the ocean were they to explore? The authorities at the Washington Observatory were appealed to. Having consulted his charts as to the direction and limits of the Gulf Stream at that period of the year, Dr. Maury traced on a chart the spot to which the disabled steamer was likely to be driven by the current, and the course to be taken by the vessels sent to her assistance.” The steamers went straight to the exact spot, and found the wreck; and although by that time the crew and passengers had been taken off by three passing vessels, it was certainly a triumph of science.

The tides are produced by two pairs of great waves which travel round the earth each day—a greater pair caused by the attraction of the moon, a lesser pair caused by the sun. The moon, by reason of its nearness to the earth, produces by far the greater influence, but the tides are also subject to all kinds of local influences. The eastern coast of Asia and western side of Europe are exposed to extremely high tides; while in the South Sea Islands they scarcely reach the height of twenty inches. There is hardly any tide in the Mediterranean, separated as it is from the ocean by a narrow strait. “The highest tide which is known occurs in the Bay of Fundy, which opens up to the south of the isthmus uniting Nova Scotia and New Brunswick. There the tide reaches forty, fifty, and even sixty feet, while it only attains the height of seven or eight in the bay to the north of the same isthmus. It is related that a ship was cast ashore upon a rock during the night so high, that at daybreak the crew found themselves and their ship suspended in mid‐air, far above the water.” The winds have an immense influence on the height of tides, and also on the waves. The highest known waves are found off the Cape of Good Hope (p. 89) at the period of high tide, under the influence of a strong north‐west wind which has traversed the Atlantic, pressing its waters round the Cape. “The billows there,” says Maury, “lift themselves up in long ridges, with deep hollows between them. They run high and fast, tossing their white caps aloft in the air, looking like the green hills of a rolling prairie capped with snow, and chasing each other in sport. Still, their march is stately and their roll majestic. Many an Australian‐bound trader, after doubling the Cape, finds herself followed for weeks at a time by these magnificent rolling swells, furiously driven and lashed by the ‘brave west winds.’ These billows are said to attain the height of thirty, and even forty feet; but no very exact measurement of the height of waves is recorded.” Those off Cape Horn are rather less in height. _Spray_ is dashed over the Eddystone Light, 130 feet high. After a great storm in Barbadoes in 1780, some old and heavy cannons were found on the shore, which had been thrown up from the bottom of the sea. If waves in their reflux meet with obstacles, whirlpools result, such as those in the Straits of Messina, between the rocks of Charybdis and Scylla made famous by Homer, Ovid, and Virgil, and once much dreaded, but now little feared.

The best known whirlpool, the Maelström, off Lofoden, in Norway, is the result of opposing currents. One of the most circumstantial accounts of it is that of a Norwegian, Jonas Ramus, who calls it the Moskoe‐strom (channel or stream):—“Between Lofoden and Moskoe,” says he, “the depth of the water is between thirty‐six and forty fathoms; but, on the other side, towards Ver (Vurrgh), this depth decreases so as not to afford a convenient passage for a vessel without the risk of splitting on the rocks, which happens even in the calmest weather. When it is flood the stream runs up the country between Lofoden and Moskoe with a boisterous rapidity; but the roar of its impetuous ebb to the sea is scarcely equalled by the loudest and most dreadful cataracts, the noise being heard several leagues off; and the vortices or pits are of such an extent and depth that if a ship comes within its attraction it is inevitably absorbed and carried down to the bottom, and there beaten to pieces against the rocks; and when the water relaxes the fragments thereof are thrown up again. But these intervals of tranquillity are only at the turn of the ebb and flood and in calm weather, and last but a quarter of an hour, its violence gradually returning. When the stream is most boisterous, and its fury heightened by a storm, it is dangerous to come within a Norwegian mile of it. Boats, yachts, and ships have been carried away by not guarding against it before they were within its reach. It likewise happens frequently that whales come too near the stream, and are overpowered by its violence, and then it is impossible to describe their howlings and bellowings, in their fruitless struggles to disengage themselves. A bear once attempting to swim from Lofoden to Moskoe, was caught by the stream and borne down, while he roared terribly, so as to be heard on shore. Large stocks of firs and pine‐trees, after being absorbed by the current, rise again, broken and torn to such a degree as if bristles grew upon them. This plainly shows the bottom to consist of craggy rocks, among which they are whirled to and fro. This stream is regulated by the flux and reflux of the sea, it being constantly high and low water every six hours. In the year 1645, early in the morning of Sexagesima Sunday, it raged with such noise and impetuosity that the very stones of the houses on the coast fell to the ground.” Kuchu and others promulgated the idea that the maelström is a watery abyss penetrating the globe, and issuing in some very remote part. This is the view held by most of the Norwegian peasantry and fishermen to‐day.

Who that has read the works of Edgar Allan Poe will ever forget his thrilling and detailed story of a descent into the maelström?(30) It bears the impress of close study, and is founded largely on recorded facts. Two brothers, the most daring fishermen of their coast, were accustomed to fish in closer proximity to the maelström than all the rest, because, although a desperate speculation, they would get more fish in a day than the others could at the distant fishing grounds in a week. The risk of life stood for labour, and courage for capital.

In a terrible hurricane they were driven through the surf into the inner circle of the whirlpool, where (as is likely to be the case in actual fact) the wind nearly ceased, the surface of the water being lower than that of the surrounding ocean. “If you have never been at sea in a heavy gale, you can form no idea of the confusion of mind occasioned by the wind and spray together. They blind, deafen, and strangle you, and take away all power of action or reflection.” Now the two fishermen brothers were in a measure respited, as death‐condemned felons in prison are allowed petty indulgences forbidden them while their doom is yet uncertain. Round and round the belt the vessel flew rather than floated, getting nearer and nearer to the fatal inner vortex, and making wild lurches towards the abyss. “The boat appeared to be hanging, as if by magic, midway down, upon the interior surface of a funnel vast in circumference, prodigious in depth, and whose perfectly smooth sides might have been mistaken for ebony, but for the bewildering rapidity with which they spun round, and for the gleaming and ghastly radiance they shot forth as the rays of the full moon ... streamed in a flood of golden glory along the black walls, and far away down into the inmost recesses of the abyss.” Round and round they swept in dizzying swings and jerks. Above and below them were whirling fragments of vessels, timbers, boxes, barrels, and trunks of trees. And now a hope arose from the recollection of one circumstance: that of the great variety of buoyant matter thrown up by the moskoe‐strom on the coast of Lofoden, some articles were not disfigured or damaged at all. Further, light and cylindrical articles were the least likely to be absorbed into any watery vortex: for the last statement there are good scientific reasons. “I,” says the survivor, “no longer hesitated what to do. I resolved to lash myself securely to the water‐cask upon which I now held, to cut it loose from the counter, and to throw myself with it into the water. I attracted my brother’s attention by signs, pointed to the floating barrels that came near us, and did everything in my power to make him understand what I was about to do. I thought at length that he comprehended my design, but whether this was the case or not, he shook his head despairingly, and refused to move from his station by the ring‐bolt. It was impossible to reach him; the emergency admitted of no delay; and so, with a bitter struggle, I resigned him to his fate, fastened myself to the cask by means of the lashings which secured it to the counter, and precipitated myself with it into the sea without another moment’s hesitation.” The smack soon after made a few gyrations in rapid succession, then sank to the bottom for ever, bearing with it the unfortunate brother. “The barrel to which I was attached had sunk very little farther than half the distance between the bottom of the gulf and the spot at which I leaped overboard before a great change took place in the character of the whirlpool. The slope of the sides of the vast funnel became momentarily less and less steep. The gyrations of the whirl grew gradually less and less violent.” By degrees the waters rose, and he found himself in full view of the shores of Lofoden, and above the spot where the pool of the moskoe‐strom _had been_. He was picked up by a boat; those on board were old mates and daily companions, but they knew him no more than they would have known a traveller from the spirit‐land. His hair, which had been raven black the day before, was now as white as snow.

Thus far Poe. It shows how the vivid imagination of a great poet, dealing with facts, can put those facts before the reader in artistically life‐ like and graphic form.

Another remarkable whirlpool is that of Corrievreckan, off the Hebrides, in the south of Scotland, shown in an illustration on page 93.

A phenomenon of another character is exhibited on the south side of the Mauritius, at a point called “The Souffleur,” or “The Blower.” “A large mass of rock,” says Lieutenant Taylor, of the United States navy, “runs out into the sea from the mainland, to which it is joined by a neck of rock not two feet broad. The constant beating of the tremendous swell which rolls in has undermined it in every direction, till it has exactly the appearance of a Gothic building with a number of arches. In the centre of the rock, which is about thirty‐five or forty feet above the sea, the water has forced two passages vertically upward, which are worn as smooth and cylindrical as if cut by a chisel. When a heavy sea rolls in, it of course fills in an instant the hollow caverns underneath; and finding no other egress, and being borne in with tremendous violence, rushes up these chimneys, and flies, roaring furiously, to a height of full sixty feet. The moment the wave recedes, the vacuum beneath causes the wind to rush into the two apertures with a loud humming noise, which is heard at a considerable distance.

“My companion and I arrived there before high water; and, having climbed across the neck of rock, we seated ourselves close to the chimneys, where I proposed making a sketch, and had just begun, when in came a thundering sea, which broke right over the rock itself, and drove us back much alarmed.

“Our negro guide now informed us that we must make haste to re‐cross our narrow bridge, as the sea would get up as the tide rose. We lost no time, and got back dry enough; and I was obliged to make my sketches from the mainland.

“In about three‐quarters of an hour the sight was truly magnificent. I do not exaggerate in the least when I say the waves rolled in, long and unbroken, full twenty‐five feet high, till, meeting the headland, they broke clear over it, sending the spray flying over to the mainland; while, from the centre of this mass of foam, the Souffleur shot up with a noise which we afterwards heard distinctly between two and three miles. Standing on the main cliff, more than a hundred feet above the sea, we were quite wet.”

To the combined influences of tides and waves may also be attributed the monsoon hurricanes which so often visit the Indian Ocean. The air may have been just previously without a breath, when immense waves, accompanied by whirlwinds, come rolling in. “At the period of the changing monsoons, the winds, breaking loose from their controlling forces, seem to rage with a fury capable of breaking up the very foundations of the deep,” and ships are often literally whirled round, or bodily lifted up, their crews being utterly impotent.

Turning to another subject, partially discussed before—the colour of the sea—it may be remarked that by itself as sea water it is really colourless. Its varying colours are caused by reflection, by the varied bottoms it covers, or by the presence of actual animal, vegetable, and mineral bodies. The ocean,

“When winds breathe soft along the silent deep,”

is azure blue or ultramarine, becoming greener in‐shore. There are some days when it is generally green, others sombre and grey. A bottom of white sand will give a greyish or apple‐coloured green; of chalk, a pure clear green; if the bottom is brownish‐yellow sand, the green is naturally duller in character. In the Bay of Loango the waters appear of a deep red, from the red bottom. The Red Sea owes its colour to actual floating microscopic algæ and to red coral bottoms. Sea water, concentrated in the salt marshes of the south of France by the heat of the sun, is also red: this is due to the presence of a red‐shelled animal of microscopic size. These minute creatures do not appear till the salt water has attained a certain concentration, while they die when it has reached a further density. Navigators often traverse patches of green, red, white, or yellow‐coloured water, their coloration being due to the presence of microscopic crustaceans, medusæ, zoophytes, and marine plants.

The pleasing phenomenon known as the phosphorescence of the sea is generally, though by no means entirely, due to myriads of minute globular creatures, called _Noctiluca_. Captain Kingman reported having traversed a zone twenty‐three miles in length, and so filled with phosphorescent matter that during the night it presented the appearance of a vast field of snow. “There was scarcely a cloud in the heavens,” he tells us; “yet the sky for about 10° above the horizon appeared as black as if a storm were raging; stars of the first magnitude shone with a feeble light, and the ‘milky way’ of the heavens was almost entirely eclipsed by that through which we were sailing.” Several varieties of molluscs and acalephes shine by their own light, while phosphorescence is often due to the decomposition of animal matter.

A French author thus describes the effect produced by the molluscs known to scientists as _Pyrosoma_, on a voyage to the Isle of France. He says:—“The wind was blowing with great violence, the night was dark, and the vessel was making rapid way, when what appeared to be a vast sheet of phosphorus presented itself, floating on the waves, and occupying a great space ahead of the ship. The vessel having passed through this fiery mass, it was discovered that the light was occasioned by organised bodies swimming about in the sea at various depths around the ship. Those which were deepest in the water looked like red‐hot balls, while those on the surface resembled cylinders of red‐hot iron. Some of the latter were caught; they were found to vary in size from three to seven inches. All the exterior of the creatures bristled with long thick tubercles, shining like so many diamonds, and these seemed to be the principal seats of their luminosity. Inside also there appeared to be a multitude of oblong narrow glands, exhibiting a high degree of phosphoric power. The colour of these animals when in repose is an opal yellow, mixed with green; but on the slightest movement the animal exhibits a spontaneous contractile power, and assumes a luminous brilliancy, passing through various shades of deep‐ red, orange‐green, and azure‐blue.” A ship plunging through these phosphorescent fields seems to advance through a sheet of white flame, a field of luminous silver, scattering a spray of sparks in all directions.