The Ocean World: Being a Description of the Sea and Its Living Inhabitants.

CHAPTER XIX.. Ossei, or Bony Fishes 529

OSSEI, OR BONY FISHES 529 Plectognathi 529 Lophobranchii 534 Malacopterygii 536 Abdominales 560 Acanthopterygians 590 Pharyngeans 596

ILLUSTRATIONS.

PLATE PAGE

I. THE ARGONAUT SAILING BEFORE THE WIND (Frontispiece) 467

II. SPONGE FISHING ON THE COAST OF SYRIA 78

III. CORAL FISHING ON THE COAST OF SICILY 138

IV. CORAL ISLAND IN THE POMOTOUAN ARCHIPELAGO 169

V. SEA ANEMONES (I.) 187

VI. SEA ANEMONES (II.) 189

VII. AGALMA RUBRA 239

VIII. GALEOLARIA AURANTIACA 244

IX. SEA-URCHINS 290

X. FISHING FOR HOLOTHURIA 295

XI. SYNAPTA DUVERNAEA 299

XII. DREDGING FOR OYSTERS 374

XIII. OYSTER PARKS ON LAKE FUSARO 376

XIV. PECTINIDÆ 386

XV. SPONDYLUS 388

XVI. ANODONTA 340

XVII. TRIDACNA GIGANTEA 338

XVIII. VENUS AND CYTHEREA 336

XIX. SOLENIDÆ (Razor-fish) 333

XX. TEMPLE OF SERAPIS 330

XXI. CONUS 427

XXII. CYPRÆADÆ 421

XXIII. VOLUTA 426

XXIV. CAPTURE OF A GIGANTIC CUTTLE-FISH 462

XXV. SHARK FISHING 520

XXVI. STURGEON FISHING ON THE VOLGA 528

XXVII. FISHING FOR ELECTRICAL EELS 539

XXVIII. GREENLANDERS FISHING FOR HALIBUT 551

XXIX. THE HERRING FISHERY 580

XXX. A ROMAN FEAST 593

XXXI. FISHING FOR TUNNY IN PROVENCE 598

XXXII. FISHING FOR MACKEREL OFF THE CORNWALL COAST 601

THE OCEAN WORLD.

CHAPTER I.. The Ocean.

THE OCEAN.

Ἄοιστον μὲν ὔδωρ--"The best of all things is water."--PINDAR.

It is estimated that the sea covers nearly two-thirds of the surface of the earth. The calculation, as given by astronomers, is as follows: The surface of the earth is 31,625,625 ½ square miles, that portion occupied by the waters being about 23,814,121 square miles, and that consisting of continents, peninsulas, and islands, being 7,811,504 miles; whence it follows that the surface covered with water is to dry land as 3·8 is to 1·2. The waters thus cover a little more than seven-tenths of the whole surface. "On the surface of the globe," Michelet remarks, "water is the rule, dry land the exception."

Nevertheless, the immensity and depth of the seas are aids rather than obstacles to the intercourse and commerce of nations; the maritime routes are now traversed by ships and steamers conveying cargoes and passengers equal in extent to the land routes. One of the features most characteristic of the ocean is its continuity; for, with the exception of inland seas, such as the Caspian, the Dead Sea, and some others, the ocean is one and indivisible. As the poet says, "it embraces the whole earth with an uninterrupted wave."

Περὶ πᾶσαν θ' εἱλισσομένου χθόν' ἀκοιμἡτω ῥεύματι.

ÆSCHYLUS in Prometheus Vinctus.

The mean depth of the sea is not very exactly ascertained, but certain phenomena observed in the movement of tides are supposed to be incapable of explanation without admitting a mean depth of three thousand five hundred fathoms. It is true that a great number of deep-sea soundings fall short of that limit; but, on the other hand, many others reach seven or eight thousand. Admitting that three thousand fathoms represents the mean depth of the ocean, Sir John Herschel finds that the volume of its waters would exceed three thousand two hundred and seventy-nine million cubic yards.

This vast volume of water is divided by geographers into five great oceans: the Arctic, the Atlantic, Indian, Pacific, and Antarctic Oceans.

The Arctic Ocean extends from the Pole to the Polar Circle; it is situated between Asia, Europe, and America.

The Atlantic Ocean commences at the Polar Circle and reaches Cape Horn. It is situated between America, Europe, and Africa, a length of about nine thousand miles, with a mean breadth of two thousand seven hundred, covering a surface of about twenty-five million square miles, placed between the Old World and the New. Beyond the Cape of Storms, as Cape Horn may be truly called, it is only separated by an imaginary line from the vast seas of the south, in which the waves, which are the principal source of tides, have their birth. Here, according to Maury, the young tidal wave, rising in the circumpolar seas of the south, and obedient to the sun and moon, rolls on to the Atlantic, and in twelve hours after passing the parallel of Cape Horn is found pouring its flood into the Bay of Fundy, whence it is projected in great waves across the Atlantic and round the globe, sweeping along its shores and penetrating its gulfs and estuaries, rising and falling in the open sea two or three feet, but along the shore having a range of ten or twelve feet. Sometimes, as at Fundy on the American coast; at Brest on the French coast; and Milford Haven, and the mouth of the Severn in the Bristol Channel, rising and falling thirty or forty feet, "impetuously rushing against the shores, but gently stopping at a given line, and flowing back to its place when the word goes forth, 'Thus far shalt thou go, and no farther.' That which no human power can repel, returns at its appointed time so regularly and surely, that the hour of its approach and the measure of its mass may be predicted with unerring certainty centuries beforehand."

The Indian Ocean is bounded on the north by Asia, on the west by Africa, on the east by the peninsula of Molucca, the Sunda Isles, and Australia.

The Pacific, or Great Ocean, stretches from north to south, from the Arctic to the Antarctic Circle, being bounded on one side by Asia, the island of Sunda, and Australia; on the other by the west coast of America. This ocean contrasts in a striking manner with the Atlantic: the one has its greatest length from north to south, the other from east to west; the currents of the Pacific are broad and slow, those of the other narrow and rapid; the waves of this are low, those of the other very high. If we represent the volume of water which falls into the Pacific by one, that received by the Atlantic will be represented by the figure 5. The Pacific is the calmest of seas, and the Atlantic Ocean is the most stormy.

The Antarctic Ocean extends from the Antarctic Polar Circle to the South Pole.

It is remarkable that one half of the globe should be entirely covered with water, whilst the other contains less of water than dry land. Moreover, the distribution of land and water, if, in considering the germ of the oceanic basins, we compare the hemispheres separated by the Equator and the northern and southern halves of the globe, is found to be very unequal.

Oceans communicate with continents and islands by coasts, which are said to be scarped when a rocky coast makes a steep and sudden descent to the sea, as in Brittany, Norway, and the west coast of the British Islands. In this kind of coast certain rocky indentations encircle it, sometimes above, sometimes under water, forming a labyrinth of islands, as at the Land's End, Cornwall, where the Scilly Islands form a compact group of from one to two hundred rocky islets, rising out of a deep sea; or in the case of the Channel, on the opposite coast of France, where the coast makes a sudden descent, forming steep cliffs and leaving an open sea. The coast is said to be flat when it consists of soft argillaceous soil descending to the shore with a gentle slope. Of this description of coast there are two, namely, sandy beaches, and hillocks or dunes.

* * * * *

What is the average depth of the sea? It is difficult to give an exact answer to this question, because of the great difficulty met with in taking soundings, caused chiefly by the deviations of submarine currents. No reliable soundings have yet been made in water over five miles in depth.

Laplace found, on astronomical consideration, that the mean depth of the ocean could not be more than ten thousand feet. Alexander von Humboldt adopts the same figures. Dr. Young attributes to the Atlantic a mean depth of a thousand yards, and to the Pacific, four thousand. Mr. Airy, the Astronomer Royal, has laid down a formula, that waves of a given breadth will travel with certain velocities at a given depth, from which it is estimated that the average depth of the North Pacific, between Japan and California, is two thousand one hundred and forty-nine fathoms, or two miles and a half. But these estimates fall far short of the soundings reported by navigators, in which, as we shall see, there are important and only recently discovered elements of error. Du Petit Thouars, during his scientific voyage in the frigate Venus, took some very remarkable soundings in the Southern Pacific Ocean: one, without finding bottom at two thousand four hundred and eleven fathoms; another, in the equinoctial region, indicated bottom at three thousand seven hundred and ninety.

In his last expedition, in search of a north-west passage, Captain Ross found soundings at five thousand fathoms. Lieutenant Walsh, of the American Navy, reports a cast of the deep-sea lead, not far from the American coast, at thirty-four thousand feet without bottom. Lieutenant Berryman reported another unsuccessful attempt to fathom mid ocean with a line thirty-nine thousand feet in length. Captain Denman, of H. M. S. Herald, reported bottom in the South Atlantic at the depth of forty-six thousand feet; and Lieutenant J. P. Parker, of the United States frigate Congress, on attempting soundings near the same region, let go his plummet, after it had run out a line fifty thousand feet long, as if the bottom had not been reached. We have the authority of Lieutenant Maury for saying, however, that "there are no such depths as these." The under-currents of the deep sea have power to take the line out long after the plummet has ceased to sink, and it was before this fact was discovered that these great soundings were reported. It has also been discovered that the line, once dragged down into the depths of the ocean, runs out unceasingly. This difficulty was finally overcome by the ingenuity of Midshipman Brooke. Under the judicious patronage of the Secretary to the United States Navy, Mr. Brooke invented the simple and ingenious apparatus (Fig. 1), by which soundings are now made, in a manner which not only establishes the depth, but brings up specimens of the bottom. The sounding-line in this apparatus is attached to a weighty rod of iron, the lower extremity of which contains a hollow cup for the reception of tallow or some other soft substance. This rod is passed through a hole in a thirty-two pound spherical shot, being supported in its position by slings A, which are hooked on to the line by the swivels a. When the rod strikes the bottom, the tension on the line ceases, the swivels are reversed, the slings B are thrown out of the hooks, the ball falls to the ground, and the rod, released from its weight, is easily drawn up, bringing with it portions of the bottom attached to the greasy substance in the cup. By means of this apparatus, specimens of the bottom have been brought up from the depth of four miles.

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