Foster quite justly decides that these circular islands are the craters of volcanoes, raised up by the polypes. He has been contradicted, but wrongly so. Upon no other hypothesis can we account for this identity of figure. There is always the same ring of about a hundred paces in diameter, very low, beaten on the outside by the waves, but enclosing a tranquil basin. A few plants of three or four species, here and there, crown the basin with verdure. The water is of the most beautiful green. The enclosing ring is of white sand, the residue of dissolved coral, contrasting with the blue of the Ocean. Beneath the salt water, our little laborers are at work, the stronger and bolder at the breakers, the weaker and more timid on the smoother sides.
This is not a very varied world. But wait. The winds and the currents are constantly at work to enrich it; come a good tempest, and all the neighboring isles will be laid under contribution to enrich this rising one. And in this is one of the most magnificent functions of the Tempest; the greater, the wilder, and the more sweeping, the more fecund it is. A water-spout passes over an island; the torrent that it produces carries with it slime, rubbish, plants, living or dead, and even whole forests, which the waves carry to the neighboring isles, raising, and at the same time enriching, their soil.
A great messenger of life, and one of the most transportable, is the solid cocoanut. Not only does it travel well, but, when thrown upon shoal or rock, if it find only a little poor white sand, which would support nothing else, the cocoanut contents itself there, finds brackish water not a jot less agreeable than the freshest; germinates, thrives, grows into a robust cocoa tree. A tree being thus planted, fresh water comes, falling leaves create earth, other trees follow, and at length we see the noble palm grove, which arrests the vapors, which at length form a rivulet or river, which, flowing from the center of the isle, make an opening of fresh water in the cincture of white sand, and thus keep the polypes, inhabitants only of salt water, at a respectful distance.
Of the rapidity with which the Polypes do their work, we have some curious proofs. In forty days' harboring at Rio Janeiro, boats were wholly destroyed; in a strait near Australia, there were formerly only twenty-six islets; there are already a hundred and fifty—well recognized: and the English admiralty believes that there are even more; and in twenty years hence the whole strait, forty leagues in length, will be so completely blocked up as to be unnavigable.
The eastern shoal of Australia is three hundred and sixty leagues, (one hundred and twenty-seven without any interruption,) and that of New Caledonia one hundred and forty-five leagues; the single shoal of the Maldives is almost five hundred miles long, and groups of isles in the Pacific are four hundred leagues long, by a hundred and fifty wide. To all this work of the Polypes, we must add, that the banks of the isle of France, and the shallows of the Red Sea, are continually rising. Tunis and its environs present a wholly animal world; and the rocks present forms so strange, and colors so splendid, that the spectator is amazed and dazzled. You see them in a space of several leagues of shallow sea water—probably not averaging more than a foot of depth, working calmly, but perseveringly at their business of creating.
Their first intelligent observer was Forster, companion of Cook, who found them at work, caught them in the very fact of their great conspiracy to make, noiselessly and marvellously, whole chains of islands, to be by degrees converted into a continent.
All this passed before his eyes, as it might have done in the first days of the world. From the submarine depths, the central fire throws up a dome or cone, which opens, and its lava forms a circular crater. But the volcanic strength becomes exhausted, and the cooling lava becomes covered with a living jelly, an animal multitude, whose perpetual exudation of mucus continually raises the circle higher and higher, to low water mark; no higher, or they would be dry; no lower, because they would lack the light. If they have no special organ with which to perceive the light, it circumfuses, penetrates, permeates their whole being. The glowing sun of the tropics, which traverses right through their transparent little frames, seems to have for them all the irresistible attraction of magnetism. When the tide ebbs and leaves them uncovered, they, nevertheless, remain open, and drink in the vivid light.
Dumont d'Urville, who so often coasted among their little isles, says:—"It is a real pain to see, so near by the peace of that interior basin, and to see all around shallow waters, beneath which are the shelving rocks, tenanted by the coral insects, in perfect security, while we are enduring all the shocks of a raging tempest." But this amiable community and its edifice are a shoal, a terrible lee shore, scarcely hidden by the shallow waters; touch upon that shoal and you will be crushed. Trust not to anchors among those peaked and jagged rocks; your cables, however good, would soon wear and snap. The seaman's anxiety is extreme, in those long nights when the Southern surges drive him among these shoals, at once so rugged and yet as cutting as razors.
To such accusations as these, our innocent shoal-makers reply—"Time—give us only time, and these rocks will become hospitable, tenanted, fruitful. These banks, joined on to their neighboring banks, will no longer have these terrible threatenings for the seaman. We are preparing a spare world to replace your old one should it perish. Ingrates! Come some great and overwhelming catastrophe to your old world, if, as some one among you has said, the sea turns from one pole to the other in every ten thousand years, and you perchance will bless us, and hail with joy these southern isles which we are making, this huge southern continent that we are preparing. Confess, now, that if, unhappily, ships do occasionally perish on these shoals, our work here, nevertheless, is useful, and good, and great. Our improvised world may not unjustly be proud. To say nothing about the beauty of its triumphant colors, before which those of your earth grow pale; to say nothing about the graceful curves and circles on which we pride ourselves,—how many are the problems, which, insolvable to you, find their solution among us! The division of labor, a charming variety combined with a great regularity, a geometrical order, softened and made graceful and gracious by a rising liberty—where, among you men, will you find these so combined as from the beginning we have combined them among us? Our incessant labor in relieving the sea-water of its salts, creates those currents which give it life and healthful power. We are the very spirits of the Sea, giving, as we do, her motion."
"And the sea is not ungrateful; she nourishes us at fixed periods; and not less punctually comes the glowing sun to caress us and dower us with brilliant colors. We are the beloved, the favored workers of the Deity, entrusted by him with the first rude sketches and outlines of his worlds, and all our juniors upon this globe, need us, and are indebted to us. Our friend the Cocoa tree, that inaugurates terrestrial life upon our isle, could not do so but from our dust. In its far back origin, vegetable life is our liberal gift, and, made rich by us, it nourishes the superior creation."