A second huge tongue of flame leaped into the sky; and then the vessel disappeared beneath the sea. Giant waves leaped in the direction taken by Jack, Frank and Harris. The sea churned angrily about them and the three had all they could do to keep their heads above water. Then the water calmed down. Frank looked around and there, not fifty feet away, rolling gently on the waves, was the small boat so recently lowered over the side of the German vessel. With a cry to the others to follow him, Frank turned about and headed for the boat with powerful strokes. CHAPTER XX FRIENDS AND FOES There was reason for Frank's haste. Swimming close together and bearing down upon the boat from the opposite direction--almost as close from their side as Frank was from his--four German sailors were racing. They espied Frank and his friends at almost the same moment Frank saw them. One uttered a cry and the others redoubled their efforts to beat Frank to the boat. Jack and Harris took in the situation quickly. It was then that Jack exerted himself to the utmost. His great, powerful strokes sent him skimming through the water as lightly as a denizen of the deep. A dozen strokes and he had passed Frank. A few more only, it seemed, and he laid hold of the boat and drew himself aboard. Standing erect he looked around quickly. Then, stepping forward, he picked up an oar. He moved to the side of the boat where the Germans were approaching and raised the oar aloft. "Keep off there!" he cried. The Germans uttered exclamations of alarm; but they came closer. "Keep back!" cried Jack, again. "But you won't let us drown!" exclaimed one of the enemy. "You stay there until my friends get aboard. Then I'll see what I can do for you," replied Jack. With this the Germans were forced to be content; for they realized that Jack held the upper hand. It would be impossible for them to climb aboard while the lad stood there brandishing that oar. Frank laid hold of the boat a moment later and clambered over the side. Harris was close beside him. Jack called a consultation. "There is plenty of room for those fellows in here," he said, "but-- shall we let them in?" "We can't see them drown," said Frank. "Still, there is no telling how long we shall be here. Is there sufficient water and food to go around?" "I'll have a look," said Harris. "Enough for seven of us for about one drink apiece," he said, after an exploration. "There is no food." "Well, what shall we do?" said Jack. "Let them come aboard," said Frank. "We can't see them perish without raising a hand to help them." "And yet they would not have helped us a short time ago," said Jack. "One man would have helped us," said Harris. "Perhaps he is one of these." "No, he's not," said Jack. "I would know him in a moment if I saw him. I obtained a good look at his face." "Let them in anyhow," said Harris.