He was getting quite exhausted, and had already been down far too long. Nothing but the strong desire to have something definite to say kept him toiling on, and at last he unwillingly gave up, when something dark amongst the sand he had thrown out took his attention, and reaching down he picked up a lump of shells concreted together, and with an impatient gesture he was about to throw them down again, when it struck him that they were uncommonly heavy. To an inexperienced man this would have passed unnoticed, for the difficulty of telling the difference of weight in so dense a medium as the water was not one easily mastered, but Dutch had been down too many times not to have a good idea of such matters, and, checking himself just as he was about to throw the mass down, he raised it to the front of his helmet.
Shells, shells, nothing but shells of several kinds joined together by the calcareous deposit of some kind of sea worm; but, all the same, it was very heavy, and, wrong or right, determining to take the lump up with him, he turned to go under the schooner and reach the ladder.
For, he argued, those little ingots the Cuban had shown them had shelly accretion firmly attached, and it was probable that a good deal had been knocked off. At all events, he must ascend now, and going slowly along, placing the piece of concrete in a net pouch at his back, he was in the shadow of the schooner with its keel nearly above his head, when a peculiar sensation that he knew too well suddenly attacked him. His head began to swim, blood seemed to gorge the vessels of his eyes, and a horrible sensation of oppression to attack his chest.
Already exhausted by his too long stay and extra exertion, combined with the nervous excitement of his fight with the shark, he was not master of himself, and in spite of his old experience he literally lost his head, becoming so unnerved that he sank down upon his knees, forgetting his signal-line, and tugging at the helmet to get it from his head.
One drag at that thin cord should have been sufficient to secure help, but it was forgotten, even though he touched it with his hands as they went to his helmet, and to make matters worse, he was kneeling now out of sight of those on deck; and for the moment all seemed over. He was blind, for a thick darkness had, as it were, come over him, mentally and bodily, in the intense horror of the moment, but through that darkness flashed scene after scene of the past, and he saw Hester, looking young and beautiful, gazing pityingly down at him, but without stretching out a hand to save, while, with a smile of triumph upon his countenance, there stood Lauré, the bane of his existence. Then came pleasant thoughts of his old childish days, mingled with a dull sense of drowsiness that it was impossible to fight against, and then a reaction, as Dutch made a violent effort to reach his feet, but only to sink down prone upon his face.
For though, like some gigantic sea worm, the india-rubber tube meandered over the sand, out of the shadow of the schooner into the sunshine, and then straight up towards the surface, the supply of air had stopped!