terior of the structure seems gradually to shelve off; so that about the centre of the inclosed, or partially inclosed space, the sea is found of its natural depth. Correspondently with such an arrangement, it happens usually that the soundings gradually lessen from the centre of the area inclosed by a coral reef, towards the exterior ridge; and then suddenly sink to two hundred fathoms or more.

To the foregoing observations I shall subjoin the opinion of captain Flinders on the process observed by nature in the formation of coral reefs. "It seems to me," he says, " that "when the animalcules, which form the coral "at the bottom of the ocean, cease to live, their "structures adhere to each other by virtue "either of the glutinous remains within, or of "some property in salt water; and the inter"stices being gradually filled up with sand and "broken pieces of coral washed by the sea,

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which also adhere, a mass of rock is at length "formed. Future races of these animalcules "erect their habitations upon the rising bank, "and die in their turn; to increase, but principally to elevate, this monument of their won“derful labours. The care taken to work perpendicularly, in the early stages, would mark "a surprising instinct in these diminutive crea"tures. Their wall of coral, for the most part "in situations where the winds are constant,

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"being arrived at the surface, affords a shel"ter; to leeward of which their infant colonies

may be safely sent forth and to this, their "instinctive foresight, it seems to be owing, that "the windward side of a reef, exposed to the open sea, is generally, if not always, the high"est part; rising almost perpendicularly, some"times from the depth of two hundred and per

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haps many more fathoms. To be constantly "covered with water seems necessary to the ex"istence of the animalcules; for they do not "work, except in holes upon the reef, beyond "low-water mark: but the coral sand, and other "broken remnants thrown up by the sea, adhere "to the rock, and form a solid mass with it, as high as the common tides reach. That ele"vation surpassed, the future remnants, being rarely covered, lose their adhesive property; and, remaining in a loose state, form what is

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usually called a key upon the top of the reef. "The new bank is not long in being visited by έσ sea birds; salt plants take root upon it, and a "soil begins to be formed; a cocoa-nut, or the

drupe of a pandanus, is thrown on shore; land “birds visit it, and deposit the seeds of shrubs " and trees; every high tide, and still more every

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gale, adds something to the bank; the form of "an island is gradually assumed; and, last of "all, comes man to take possession i."

i Flinders's Voyage, vol. ii. p. 115, 116.

Р

In the base of a coral island of the above description, captain Flinders distinguished not only the sand, coral, and shells, formerly thrown up, in a more or less perfect state of cohesion; but also small pieces of wood, pumice-stone, and other extraneous bodies, which chance had mixed with the calcareous substances when the cohesion began, and which in some cases were still separable from the rock without much forcek. Such sand-banks are found in different stages of progress; some being overflowed with every returning tide; some raised above high-water mark, but destitute of vegetation; some, lastly, habitable and abounding in trees.

Let us here pause for a moment to contemplate the wonderful effect produced by apparently the most inadequate means. And wonderful indeed is the effect, even if the process above described were now to cease for ever; but much more, if we look to its probable extension: for, reasoning on what has already been accomplished, and on what is at this moment rapidly advancing, it is evidently probable that a new habitable surface of land may be eventually produced, equal in extent to the whole of Europe, and produced by the agency of a tribe of animals, which occupy very nearly the lowest steps in the scale of animal creation, and which

k Flinders's Voyage, vol. ii. p. 116.

in every other respect are the most inefficient and helpless of creatures. For, fixed as they are, both individually and collectively, to a completely local habitation; or, rather, buried as it were in a strong mass of coral, their general appearance and mode of growth so little resemble the animal character, that, for a long time, many of the species were considered as of vegetable origin; and are, even now, very commonly called zoophytes, or animated plants.

Nor let us fail to observe, in the foregoing account, the physical fitness for each other of two very different departments of nature. The same geographical climate which gives birth to those animals, whose labours produce this previously unexpected habitable surface, gives birth also to those vegetables, which, at the same time that they are capable of growing on so loose and poor a soil, are capable besides of supplying its future inhabitants not only with nutritious food, both in a liquid and a solid form, but with materials for constructing their habitations, and for many other useful other useful purposes. And in the mean time the fowls of the air, and the very winds and waves, are all employed in administering to the beneficent intentions of Providence. Of little use would be a new habitable surface, were it never to be tenanted by human beings; and in vain would man attempt to colonize that surface, were it barren of ve

getable productions: but the seeds of various plants, as we have seen in the foregoing descriptions, are either brought by birds, or drifted by the wind and waves, to a soil calculated to support them.

Among the vegetable productions of coral islands, the cocoa-nut tree stands preeminent in value; containing in itself nearly all those important properties, which are found at large in that natural family of plants, the palms: and valuable indeed are those properties, if we may rely on the accounts which have been given of them by different authors; and of the truth of those accounts there is no sufficient reason to doubt. Johnston', speaking of the abundance of the cocoa-nut tree in India, where he says it occurs to a greater extent than the olive in Spain, or the willow in Holland, affirms that there is no part of the tree which is not applied to some useful purpose. Not only the cabins of the poorer natives, but large houses, are constructed entirely with materials afforded by this tree; the trunk, when split, supplying rafters, &c.; and the leaves, when plaited, making roofs and walls, which are impervious to wind and rain. The statement of Johnston is confirmed by captain Seely, in his account of Elloram, who says that "when he was stationed at

1 Johnstonus de Arboribus, p. 146, &c.

m London, 1824, 8vo. p. 284: