He got the shell, and made a very important discovery at one and the same time. Happening to glance upward as he came to
the surface, his quick eye saw a low, narrow opening leading directly into what seemed to be the solid rock.
The mouth of the cavern was slightly shelving, and situated a little less than mid-way of the centre of the arch.
Frank lost no time in climbing into it, and was surprised to find himself in a semi-dark, sea-scented cavern, in shape something like an old-fashioned Dutch oven and fully seven feet in height.
There was sufficient light to enable him to see that the floor of the cave was thickly strewn with fragments of shells and gray-white coral, the stone itself being so soft that he could easily penetrate it with his jack-knife.
These submarine caves or grottos are numerous in the Bermudas, and the limestone rock of which they are mainly formed so extremely impressionable as to be readily cut into blocks for building purposes with a common saw.
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.