Frank remembered having heard Captain Thorne speak of them, but he little thought at the time that he would ever be the discoverer of one on an island in the midst of the Caribbean Sea. Solitude, and having to look out for himself, as the saying goes, if it had done nothing else, had sharpened his wits, and he was not long in coming to the conclusion that, by enlarging the cave inland, he could make an opening quite near his tent, and thus have both a dry and wet-weather habitation. He returned to the beach, where the Sea Eagle was daily sinking deeper and deeper in the sand, full of his new plans. He could hardly prepare his supper, so eager was he to begin work on his latest project and have his stores securely housed before the rainy season set in. He went to bed early, but was up with the dawn, ate his breakfast while yet the rays of the rising sun were but faintly illumining the east, and then, with hatchet and hammer and saw, some coils of stout rope and a plentiful supply of food, set out for the cave. He was not long in reaching it, and by noon had cut through five feet of the calcareous stone, piling up the portion cut away in a kind of wall on the lower side, where the rocky floor sloped somewhat precipitously, forming a channel, through which a considerable rivulet stole silently along, to join and lose itself in the great ocean that for miles and miles surrounded it on every hand. For four whole days he worked like a Trojan, cutting away and piling up the soft, limy stone, and on the fifth was rewarded by a glimmer of sunlight shining through the aperture he had made in the landward part of the rock. From the small opening he could see the tent, the tall palm trees that sheltered it from the fierce rays of the meridian sun and the tapering masts of the old schooner as she lay fast aground on the blistering strand, and the landwash lazily undulating against her stern. A little way beyond, some gulls and a blue heron were watching for flying-fish, great numbers of which would every once in awhile skim like so many silver leaves over the surface of the water, coming up and going down at short intervals, more in fear than play, for no doubt their relentless enemies, the dolphins, were after them, with a view to making a meal off as many as were so unfortunate as to come within their reach. Frank could not repress a shout of delight, in which there was mingled a good deal of pardonable triumph, when he nimbly scrambled through the narrow aperture he had made with so much patient toil, and stood on the firm, warm earth without the gray, damp cavern. All about his feet grew luxuriant ferns, soft mosses and trailing vines, the vegetation gradually lessening as it met the base of the dark rock forming the roof of the cave, and disappearing altogether before it reached the summit, or what Frank judged would be the summit if one were to approach it from the direction of the tent.