All made a mad dash and in a moment the entrance through the conning tower was hermetically sealed behind them. "Submerge!" cried Lord Hastings; and as the D-16 once more sank from view, her commander wiped the beads of perspiration from his forehead with his sleeve. "Whew!" he exclaimed. "Pretty close! Pretty close! But we are all safe, and that's enough!" "Right, sir," said Jack. "And enough's a plenty!" CHAPTER XV. INTO THE BALTIC. Lord Hastings called Frank and Jack into consultation to decide upon what should be done. "We are likely to have all the German submarines in these parts on our trail," he said, "and while we might hope to dispose of some of them, we can hardly hope to beat them all. My advice is that we get out of the Kiel canal at the earliest possible moment." "I agree with you, sir," said Jack. "And I, too, sir," declared Frank. "Good," from Lord Hastings. "Then we shall do so. As long as we are headed for the Baltic, we may as well go in that direction." So it came about that the British submarine, D-16, plunging swiftly on, struck out boldly for Russian waters. From the prisoner Lord Hastings was able to get his bearings, and this fact, together with his charts, permitted him to lay a course that would, he believed, bring the submarine into the Baltic Sea in safety. "Don't you think it would be advisable," asked Frank, "to attempt to sink a couple or more Germans?" "I hardly think so," was his commander's reply. "We already have done considerable damage and the next venture might not have the same success. No, I believe that we had best be content with what we have done, and get away now." Jack agreed with Lord Hastings, and Frank, finding that the sentiment was against him, was convinced that he was wrong, and said so. As the submarine made her way along, Lord Hastings decided that, as they had been so long without news of what was going on at other points in the great war zone, it would be advisable to question their prisoner along this line. "We'll have him up and learn what's what," he told the two lads. Accordingly Frank went to fetch him, and a few minutes later all were comfortably seated in the commander's cabin. Lord Hastings informed the prisoner what they desired of him, and the latter was nothing loath to enlighten them. "Possibly the matter of greatest moment at this time," said the prisoner with some show of pride, "is the German blockade of Great Britain and the coast of Northern France." Lord Hastings was on his feet in an instant. "Blockade of Great Britain!" he ejaculated. "Why, it's impossible. The German fleet itself is bottled up by our ships. How, then, can they blockade England?" The German smiled.