"No," returned Jack, "and I am rather afraid to swim under there. The balloon may sink and carry me under. But if I were certain in exactly what spot the man is imprisoned, I'd have a try at it." Frank listened attentively; and directly the German's voice came again. To Frank it seemed that the voice came from directly ahead of him. "Lay hold of this end here," he said to Jack. "If you can lift it a bit I'll go under and have a look." "Better let me do it, Frank," said Jack. "No; you're stronger than I am. You can hold this up better." Jack did as his chum requested and a moment later Frank disappeared under the wreckage, diving first to make sure that he got under. Under the water the lad swam forward. His hand touched something that was threshing about. He felt sure it was the German. He rose. His head came in contact with something, but the lad opened his eyes and saw that he was above the surface. The imprisoned German was close beside him. "Dive!" said Frank. "You can come out all right." "Can't," was the reply. "My arm is caught." Frank made a quick examination. "I can loosen it," he said at last, "but I'll probably break the arm." "Loosen it," said the German, quietly. Frank took a firm hold on the arm at the elbow and gave a quick wrench. He felt something give, and when he released his hold on the man's arm, the latter sank suddenly. Frank dived after him quickly. It was even as the lad feared. The German had fainted from the pain of the arm, which Frank had broken cleanly as he released it. Frank dived deep and his outstretched hand encountered the German. The lad grasped the man firmly by the collar and then struck upwards. A moment later he succeeded in making his way to where Jack still tugged at the balloon. Jack lent a hand and they dragged the German from beneath the wreckage. Then they towed him to the boat and other hands lifted him in. Frank and Jack clambered aboard. "Give way!" said Jack, sharply. The boat moved toward the battleship; and even as it did so, the mass of wreckage suddenly disappeared from sight with a loud noise. Jack shuddered. "Pretty close, Frank," he said quietly. "You can see what would have happened if you had still been under there." CHAPTER IV ATHLETICS "Can you fight?" The speaker was a young British midshipman. Jack and Frank stood at the rail, gazing off toward the distant horizon, when the young man approached them. The lads turned quickly. "Can you fight?" demanded the young man again. His eyes rested on Jack. "Well," said the latter with a smile, "I can if I'm pushed to it. Who wants to lick me now?" The young midshipman also smiled. "It's not that kind of a fight I'm talking about," he said. "You're new aboard, so I'll explain." "Do," said Jack.