Its centre is the apogee of terrestrial energy, in vegetable treasures, in monsters, in spices, in poisons. From the secondary currents which it gives off, and which flow towards the North, results another world, that of the Sea of Coral. There, says Maury, over a space as large as the four continents the polypes are industriously building thousands of islands, shoals, and reefs, which are gradually studding and dividing that sea; shoals which at present are the annoyance and the dread of the mariner, but which will at length rise to the surface, join together to form a continent, which, some day—who knows? may be the refuge of the human race, when flood, or fire, or earthquake, leave it no other shelter.
John Reynaud in his fine article in the Encyclopedie, remarks that our world is not solitary. The infinitely complicated curve which it describes represents the forces, the various influences, which act upon her, and bear testimony to her connection and communication with the great luminaries of the Heavens.
That connection and communication are especially visible with the Sun and Moon; the latter, though the servant of earth, has none the less power over her. As the flowers of the earth turn their heads sunward, so does the flower-bearing earth aspire towards him. In her most movable portion, her immense fluid mass, she raises herself and gives visible token of feeling his attraction. She rises as far as she can and swelling her bosom twice a day gives, at least, a sigh to the friendly stars.
Does not our earth feel the attraction of yet other globes? Are her tides ruled only by the sun and moon? All the learned world say it, all seamen believe it; thence terrible errors resulting in shipwrecks. At the dangerous shallows of Saint Malo the error amounted to eighteen feet. It was in 1839 that Chazallan, who nearly lost his life through these errors, began to discover and calculate the secondary, but considerable undulations which, under various influences, modify the general tide. Stars less dominant than the sun and moon have, doubtless, their share in producing the alternate rise and fall of the waters of our globe. But under what law do they produce this effect? Chazallan tells us;—"the undulation of the tide in a port follows the law of vibrating chords." A serious and suggestive sentence, that, which leads us to comprehend that the mutual relations of the stars are the mathematical relations of the celestial music, as antiquity affirmed.
The earth, by great and secondary tides, speaks to the planets, her sisters. Do they reply to her? We must think so. From their fluid elements they also must rise, sensible to the rise of the waters of the earth. The mutual attraction, the tendency of each star to emerge from egotism, must cause sublime dialogues to be heard in the skies. Unfortunately the human ear can hear but the least part of them. There is another point to be considered. It is not at the very moment of the passing of the influential planet that the sea yields to its influence. She is in no such servile haste to obey; she must have time to feel and obey the attraction. She has to call the idle waters to herself, to vanquish their inert force, to attract, to draw to her the most distant. The rotation of the world, too, so terribly rapid, is incessantly displacing the points subjected to the attractive power. To this we must add that the great army of waves in its combined motion has to encounter all the opposition of natural obstacles,—islands, capes, straits, the various curvings of shores, and the no less potent obstacles of winds, currents, and the rapid descent of mountain torrents, swelled by the melted snows;—these, and a thousand other unforseen accidents occur, to alter the regular movement into terrible strife. The ocean yields not. The display of strength which is made by broad and swift rivers cannot intimidate him. The waters, that the rivers pour down upon him, he heaps them up into mountainous masses and drives them back so violently that he seems bent on forcing them to the summits of the mountains from whence they have descended.
Obstacles thus numerous and various cause apparent tidal irregularities, which at once impress and confuse our minds. None of those irregularities is more surprising than the difference of their time between two quite closely neighboring ports. One Havre tide, for instance, equals two of Dieppe,—as is mentioned by Chazallon, Baude, &c. It is greatly to the honor of human genius to have subjected phenomena so complex to even proximately accurate calculation and positive laws.
But beneath these exterior movements, the sea has others within; those under currents by which she is traversed in various directions and at varying depths. Superposed at different depths, or flowing laterally in opposite directions, hot currents in one direction, cold counter currents in another, they, between them, keep up the circulation of the sea, the exchange of salt and fresh waters, and the alternating pulsation which is the result. The hot pulse-beat is from the line to the pole; the cold, from the pole to the line. Shall we be warranted in saying, as it has sometimes been said, that these currents so distinct and unmingling, may be strictly compared to the vessels, veins and arteries, of the superior animals? Strictly speaking, we cannot so compare them; but they have considerable resemblance to the less determinate circulation which materialists have lately discovered in some inferior creatures, as molluscs and annelides. That lacunary circulation supplies the want of, and at the same time prepares, the vascular; the blood flows in currents before it has precise channels.
Such is the sea. She resembles a vast animal that has stopped short at the first degree of organization. Who has developed the currents, those regular fluctuation of the abysses into which we never descend? Who has taught us the geography of those dark waters? Those that live within or float upon those waters;—animals and vegetables. We shall see how the huge whale and the minute shelled atomies, how even the woods of America, floating to bleak Iceland, have concurred in revealing the flow of hot water from the Antilles to Europe, and the counter current of cold meeting it at Newfoundland, passing it beside or below, and thus getting its ices melted into immense fogs.