Stewart's Atoll (8° 22′ S., 162° 58′ E.) is a semi-lunar coral reef of about sixteen miles in circumference, with a deep lagoon in its centre, and five small wooded islands on the reef itself, which are visible from the deck of a ship about twelve miles away, and were first discovered by Captain Hunter, in May, 1791. These islands are named Sikayana, Fáole, Mandúiloto, Baréna, and Maduáwe, and are so overgrown with cocoa-nut palms, that they appear capable of supporting a population of about 1000 souls (with the wants and requirements of men in the tropics).
The two largest islands, Sikayana and Fáole, lie exactly at the sharp horns of the lune-shaped atoll. Here we again
had an opportunity of observing the configuration of which all known atolls furnish examples, viz. that the islands found adjoining these reefs are almost invariably at the projecting extremities, where the surf rages on either side, and where consequently the conditions are most favourable for the heaping up of detached fragments of coral. The area of habitable dry land is to the extent of the reef in the proportion of 1 : 21. As may readily be assumed from the physical conditions of the islands, there is no drinkable water to be found upon them; the liquid contents of the cocoa-nut when fresh is almost the only beverage of the inhabitants, and hence the first thing the natives asked for when they came on board was for some "drinking-water," since, except of course during the wet season, when they catch the rain-water, this is a rarity with them—we might almost say an article of luxury.
Sikayana, the Big Island of the English, the most easterly and largest of the islands, is about 1 1⁄6th statute mile in length, and lies in 8° 22′ 24″ S., and 163° 1′ E. The reef which surrounds the island sinks at certain points sheer downwards, so that a ship may in perfect safety approach within a cable's length. We had to sail for a considerable time along this line of reef, on which the sea beat with a thundering surf, ere we came to one of those spots on the N.W. side where it is practicable in a boat to pass the atoll reef into the tranquil lagoon, which it encloses. At all times, even in the calmest weather, a tremendous surf roars against the reef, and even this point is inaccessible when there is a fresh breeze blowing. Here
we found some of the canoes of the natives awaiting our approach, who now, as though they had been on the look-out for our arrival, came off to us, some in their boats, others swimming, to inform us that, it being ebb-tide, the entry into the lagoon was not very easy, but that at high-water one could pass right over the reef, in even larger boats than ours. It was accordingly arranged that two of the boats should anchor outside the reef, and only one should be hauled inside the lagoon with a rope for our further use. But even this could not be managed until by removing all baggage and transhipping almost her entire crew, she had been made sufficiently light.
The passage between the coral reefs and the lagoon is at high-water about three feet deep, but at lowest ebb it is barely a foot in depth, and three to four feet wide, and then the reef juts up at most points to such extent, that a skilled equilibrist may (although not to the advantage of his soles) easily reach the interior of the lagoon without wetting his shoes. As soon, however, as this narrow entrance, which is about 300 feet long, has been passed, the navigation becomes easier. The appearance of the reef was very peculiar. Corals of every description, Astrææ, Mæandrinæ, Madriporæ, form a sort of series of clusters of stone-bushes, among which beautifully mottled fish swim about, while starfish of an exquisite indigo blue, and mussels of the most extraordinary forms, people the ground.
The atoll presents some very remarkable geological features. At its N.W. side, close to the reef and as it were growing to it, stand two singular vase-shaped rocks, from 8 to 10 feet in
height. While their base is bathed by the sea, their upper portions, which are about 20 feet in diameter, present the spectacle of luxuriant grass, brushwood, and one or two fruit-bearing cocoa-nut palms, so that the two crags looked like two gigantic flower-pots attached to the reef. They seem to be all that remains of an island which Ocean had first thrown up, and was now busy wearing away.
Another geological peculiarity is the occurrence of heaps of pumice-stone. These are found about the size of walnuts over the entire interior of the island of Fáole at those places which the swell of the waves cannot reach even in the stormiest weather, where they occur in such immense quantities (though there are no traces of them on the sand or shingle of the actual beach) that we may take for granted that the convulsion which brought them here must have occurred in times long gone by, the more so as this superposed pumice-stone exercises a marked and obvious influence upon the vegetation of the island. So far as its soil consists of heaps of fragments of coral and mussel-shells, the cocoa-nut palm reigns almost alone, whereas as soon as the pumice-stone region is reached, there begins an exceedingly luxuriant growth of lofty forest trees with huge trunks and umbrageous foliage, and an astonishingly abundant flora of species apparently peculiar to these Atoll islands. The English naturalist Jukes, who accompanied Captain Blackwood on his survey of Torres Straits, found beds of pumice along the entire east and north coasts of Australia, over an extent of 2000 miles, and under numerous
special conditions, but most frequently on flat grounds elevated about ten feet above high-water mark and more or less distant from the beach—never upon the beach itself. The occurrence of pumice in such vast quantities is of no slight interest in a geological point of view. It must have been some tremendous natural convulsions, an earthquake wave of enormous lateral dimensions, which threw up this pumice-stone, and deposited it throughout this entire region at the same height above high-water mark. Since this phenomenon occurred, the general level of the coasts and islands on which this deposit of pumice is found, can scarcely have undergone any considerable alteration, if one is not inclined to assume for the entire region a perfectly equal elevation or depression.