The boat was obliged to pass round one end of this last-named reef, where there was deep water, and then to haul its wind a little in order to reach the shore.

It would be difficult to describe the sensations with which Mark first landed. In approaching the place, both he and Bob had strained their eyes in the hope of seeing some proof that their shipmates had been there; but no discovery rewarded their search. Nothing was seen, on or about the island, to furnish the smallest evidence that either of the boats had touched it. Mark found that he was treading on naked rock when he had landed, though the surface was tolerably smooth. The rock itself was of a sort to which he was unaccustomed; and he began to suspect, what in truth turned out on further investigation to be the fact, that instead of being on a reef of coral, he was on one of purely volcanic origin. The utter nakedness of the rock both surprised and grieved him. On the reefs, in every direction, considerable quantities of sea-weed had lodged, temporarily at least; but none of it appeared to have found its way to this particular place. Nakedness and dreariness were the two words which best described the island; the only interruption to its solitude and desolation being occasioned by the birds, which now came screaming and flying above the heads of the intruders, showing both by their boldness and their cries, that they were totally unacquainted with men.

The mound, in the centre of the reef, was an object too conspicuous to escape attention, and our adventurers approached it at once, with the expectation of getting a better look-out from its summit, than that they had on the lower level of the surface of the ordinary reef. Thither then they proceeded, accompanied by a large flight of the birds. Neither Mark nor Bob, however, had neglected to turn his eyes towards the now distant ship, which was apparently riding at its anchor, in exactly the condition in which it had been left, half an hour before. In that quarter all seemed right, and Mark led the way to the mount, with active and eager steps.

On reaching the foot of this singular elevation, our adventurers found it would not be so easy a matter as they had fancied, to ascend it. Unlike the rest of the reef which they had yet seen, it appeared to be composed of a crumbling rock, and this so smooth and perpendicular as to render it extremely difficult to get up. A place was found at length, however, and by lending each other a hand, Mark and Bob finally got on the summit. Here a surprise was ready for them, that drew an exclamation from each, the instant the sight broke upon him. Instead of finding an elevated bit of table-rock, as had been expected, a circular cavity existed within, that Mark at once recognised to be the extinct crater of a volcano! After the first astonishment was over, Mark made a close examination of the place.

The mound, or barrier of lava and scoriæ that composed the outer wall of this crater, was almost mathematically circular. Its inner precipice was in most places absolutely perpendicular, though overhanging in a few; there being but two or three spots where an active man could descend in safety. The area within might contain a hundred acres while the wall preserved a very even height of about sixty feet, falling a little below this at the leeward side, where there existed one narrow hole, or passage, on a level with the bottom of the crater; a sort of gateway, by which to enter and quit the cavity. This passage had no doubt been formed by the exit of lava, which centuries ago had doubtless broken through at this point, and contributed to form the visible reef beyond. The height of this hole was some twenty feet, having an arch above it, and its width may have been thirty. When Mark got to it, which he did by descending the wall of the crater, not without risk to his neck, he found the surface of the crater very even and unbroken, with the exception of its having a slight descent from its eastern to its western side; or from the side opposite to the outlet, or gateway, to the gateway itself. This inclination Mark fancied was owing to the circumstance that the water of the ocean had formerly entered at the hole, in uncommonly high tides and tempests, and washed the ashes which had once formed the bottom of the crater, towards the remote parts of the plain. These ashes had been converted by time into a soft, or friable rock, composing a stone that is called tufa. If there had ever been a cone in the crater, as was probably the case, it had totally disappeared under the action of time and the wear of the seasons. Rock, however, the bed of the crater could scarcely be yet considered, though it had a crust which bore the weight of a man very readily, in nearly every part of it. Once or twice Mark broke through, as one would fall through rotten ice, when he found his shoes covered with a light dust that much resembled ashes. In other places he broke this crust on purpose, always finding beneath it a considerable depth of ashes, mingled with some shells, and a few small stones.

That the water sometimes flowed into this crater was evident by a considerable deposit of salt, which marked the limits of the latest of these floods. This salt had probably prevented vegetation. The water, however, never could have entered from the sea, had not the lava which originally made the outlet left a sort of channel that was lower than the surface of the outer rocks. It might be nearer to the real character of the phenomenon were we to say, that the lava which had broken through the barrier at this point, and tumbled into the sea, had not quite filled the channel which it rather found than formed, when it ceased to flow. Cooling in that form, an irregular crevice was left, through which the element no doubt still occasionally entered, when the adjacent ocean got a sufficient elevation. Mark observed that, from some cause or other, the birds avoided the crater. It really seemed to him that their instincts warned them of the dangers that had once environed the place, and that, to use the language of sailors, "they gave it a wide berth," in consequence. Whatever may have been the cause, such was the fact; few even flying over it, though they were to be seen in hundreds, in the air all round it.

Chapter V

*

"The king's son have I landed by himself;
Whom I left cooling of the air with sighs
In an odd angle of the isle, and sitting,
His arms in this sad knot."

Tempest.

Having completed this first examination of the crater, Mark and Bob next picked their way again to the summit of its wall, and took their seats directly over the arch.