Frank looked at his captive long and searchingly. There was still a doubt of the German's honesty of purpose in his mind, and for a moment he was undecided. "We must rise at once," said the German. Frank made his decision quickly. "Very well," he said quietly. He stepped to the signal tube and gave the necessary order. A moment later the rising of the vessel became perceptible, as the water was slowly forced from her tanks. Frank, not perfectly satisfied, however, stood facing the German officer, his hand on his revolver, determined to use it at the first sign of treachery. But his uneasiness was without cause. When the submarine had risen the required distance, at a word from the German, her speed was increased and she moved forward again. "Is there not danger of striking a mine up here?" asked Frank. "There are a few about," was the reply, "but I can guarantee that we shall not strike one. When the depth of the water permits, we shall go lower again." With this Frank was forced to be satisfied. His four hours up, Frank was relieved by Lord Hastings, to whom he related what had occurred. Lord Hastings listened quietly. "I'm sure he will try no tricks," he said. "However, I'll keep an eye on him." "Still," said Frank, "I have a premonition that all is not right." Lord Hastings laughed, and Frank retired. Now the Kiel canal is not very long, sixty-one miles of water connecting the North and Baltic seas. It extends across the narrowest portion of Germany close to the boundary between Germany and Denmark, thus making a passage for German vessels from one sea to the other. Lord Hastings had kept his own reckoning and believed, while he was not familiar with these waters, that he could determine when the Baltic end of the canal had been reached. And, indeed, it seemed that he was right. It was just after his watch, when Jack had relieved him and while he lingered in the compartment, that the German turned to Lord Hastings and said: "You may rise now. You have done what it has been believed impossible for any hostile ship to do. You have passed through the Kiel canal." At that moment Frank, refreshed by a few hours' sleep, entered. As Lord Hastings was about to give the signal to rise, Frank stepped forward. "One moment, sir," he exclaimed. "Something tells me that all is not right. We had best be careful, sir." The German drew himself up. "Do you mean to insinuate----" he began. Jack silenced him with a word. Then he, too, turned to Lord Hastings. "I can't explain why, sir," he said, "but I believe Frank is right. Also, you may remember, sir, how he has been right on more than one occasion and that you said hereafter you would place unusual confidence in his premonitions." "Bosh," said Lord Hastings scornfully. "It is true I did say that, but this time there can be no mistake. I have kept the reckoning myself, and the German is right. By this time we should have reached the Baltic end of the canal."