The conclusion was evidently due to the firing of a dynamite cartridge, but, in spite of this, here was the reason for their trying to drag him to the surface, in the shape of something dim and large approaching him slowly, and apparently without effort. As he saw it at first coming end on, it seemed to him like some very short, thick fish, but as it neared him, and grew more distinct, it swerved off to his right, and his heart beat fast as he saw from its altered position that it was a shark seven or eight feet long. He signalled again, "More air--all right," and the tightening life-rope slackened as he drew the long, keen-bladed knife from its wooden sheath. It was a terrible weapon, with a fine point, and about eighteen inches long beyond the handle, while its two edges were ground as sharp as a razor. Armed with this he awaited the coming of the shark, feeling that to it he must prove as he looked, a monster as deadly in his power. For Dutch agreed that to leave the field on this first encounter with one of the creatures that infested these waters was to confess to himself that he was beaten, and morally to consent to a defeat of their project, while could he nerve himself to boldly meet the attack, and so disable his enemy by skilful tactics as to kill it, or compel its retreat, he would give himself so much confidence, and Rasp as well, that they would in the future have little compunction in descending, and scarcely any fear of their dangerous enemies. "If I fail," he said to himself bitterly; "well, it is a horrible death, but why should I mind dying? I have nothing to live for now." "Bah! Dying," he went on, mastering his trepidation, and feeling a savage energy of will. "I, a man with reasoning powers, with ingenuity enough to help to invent the apparatus by which I can stay down here and meet this creature with arms in my hand in his own element. Pooh! it is absurd. I shall--I will kill it." He had plenty of time to think, and he had once more to impatiently signal "All right," for he became aware of a tightening of the life-line, while the shark, with its curious, crafty look, undulated by him, its long, unequally-lobed tail waving softly as it nearly passed him with the greatest apparent ease, turned, sailed back some little distance, and then turned once more as if to pass him on the other side. "That is where he has the advantage," thought Dutch, as he saw the ease with which the creature glided along, on about a level with the top of his helmet, and knew for his own part what an effort it needed for him to move through the water.