"Good-bye, old fellows," said Tom; "we must lose no more time." And he and Archy shook hands with all round. "Now, Archy, we will start, and strike out bravely." Tom suiting the action to the word slipped into the water, Archy did the same. On they went, keeping alongside each other. Archy found that he could swim better than he had expected, and he and Tom cheered up each other. "I wish Gerald had been with us," said Tom. "Our chances of escape are better than those on the wreck." Now and then they turned on their backs, resting for a little; striking out, however, with their arms and legs, so that they still made headway. Tom, under his brother's instructions, had become a first-rate swimmer, and for his age was wonderfully muscular; so that he was able to go on steadily without feeling exhausted. Archy, though taller and bigger, from having had less practice, more quickly began to feel fatigued. The shore seemed a long way off; still they had already, they saw, not a considerable distance from the boat, for they could scarcely distinguish her as she floated just above the surface. Tom thought that they must be a mile from the shore. Again they threw themselves on their backs, pushing on with their feet and keeping their arms moving round and round. When Tom looked back, he could no longer see the boat; he did not, however, tell Archy of this, he could not help fearing that she had sunk. "Are you rested, Archy?" he asked. "Yes!" was the answer, though not in quite so confident a tone as Tom would have liked. "Well, then, on we go again," said Tom, and they swam steadily forward as before. Scarcely a minute after this, as Tom cast his eye on one side, what was his horror to observe the fin and back of a huge shark, scarcely more than a fathom from him. The monster shot by. "I only hope it is steering a different course to ours," thought Tom. Just then he caught sight of the wicked eye of another at the same distance, following in the wake of the first. He did not tell Archy what he had seen, for fear of unnerving him, while he kept striking out with might and main, letting his feet rise higher than he would otherwise have done for the sake of creating a splash, and shouting as he swam on-- "Strike away, Archy. Bravo! We are getting on famously." Archy in the meantime was doing his best, though his legs and arms began to ache; still he resolved, as long as his strength would hold out, to persevere. At length he felt that he could do no more. "Go on, Tom," said he faintly. "Make the best of your way on shore and get help for the poor fellows, I will follow as fast as I can." "No! no!" answered Tom, "I am not going to desert you, come rest your head on my chest. It will help you wonderfully, just consider me a piece of cork, you know I float like one, only keep your legs kicking and your arms moving smartly."