The firing continued, and the crews of the two guns which sent their shot in chase vied with each other in their efforts to hit a spar and bring down the sails of the schooner; but they tried in vain. Sails were pierced, but no other harm was done, and the slaver kept gallantly on. But all her efforts were in vain. The _Nautilus_ crept on and on, nearer and nearer, till she was only about a quarter of a mile away, and then the slaver altered her course, and gained a little by her quick handling. But the _Nautilus_ was after again, and after two or three of these manoeuvres Captain Maitland was able to anticipate her next attempt to escape, and all seemed over. "I wonder how many poor wretches she has on board?" tried Mark, excitedly, as the word was passed for one of the boat's crews to be ready for boarding as soon as the slaver captain struck the flag he had run up in defiance. "Hundreds perhaps," said Bob, coolly; "but we haven't got her yet." "No; but they're going to give in now. I can see the captain quite plainly," said Mark, who was using a glass. "What are they doing? Oh, Bob, look!" For through the glass he saw what seemed to be a struggle on the moonlit deck, and directly after there was a splash. "Great heavens!" cried Captain Maitland. "Staples! Look! They're throwing the poor fellows overboard." "No," said the first lieutenant, with his glass to his eye; "only one." A mist came for a moment over Mark Vandean's sight, but it passed away; and, with the feeling of suffocation at his throat increasing now, he kept his glass upon the black head in the midst of the quivering water, where a man was swimming hard for life. Brought almost close to him by his powerful glass, Mark could nearly make out the agonised look upon the swimmer's face, as, at every stroke, he made the water shimmer in the moonlight; and every moment as his forehead grew wet and his hands clammy, the midship, man expected to see the waves close over the poor wretch's head. Just then his attention was taken up by the voices of the Captain and lieutenant. "The scoundrel! the fiend!" cried the former, with a stamp of rage upon the deck; "if it were not for those on board I'd sink him." "I wish we could, sir," replied the first lieutenant; "we shall lose him." "No," cried the captain. "He has thrown that poor wretch overboard, believing that we shall heave to and pick him up sooner than let him drown." "While he gets a mile away," said the first lieutenant; "and as soon as we overhaul him again, he'll throw over another--that is, sir, if we stop to pick the poor creatures up." "Help! boat! help!" cried Mark, unable to contain his feelings longer; and lowering his glass, he turned to the captain. "Look, sir, look!" he cried, pointing in the direction of the drowning black; "the poor fellow's going down." CHAPTER THREE. SAVING A BROTHER'S LIFE.