The sub braced himself together. He realized that in his opinion he ought to be taking part in the fun instead of remaining cooped up in a cabin, incapable of raising a finger to save himself should anything occur. He had no doubt as to the justifiability of his resolve; had there been only a private feud between Captain Restronguet and Karl von Harburg he would have hesitated, but the German had been guilty of international outrages. He had actually committed damage to the property of a foreign Government, and by so doing had very nearly succeeded in drawing Great Britain into a dreadful war. On that account Karl von Harburg was a pirate, a national enemy, and as such might be captured or destroyed. Having quickly made up his mind Hythe left the cabin and hurried along the alley-way; but before he had traversed half its length a dull thud seemed to strike the port side of the submarine. The "Aphrodite" staggered under the blow and heeled over to starboard. For some moments the vessel showed no signs of recovering, then slowly she righted and swung over to port, ere she settled in her normal position. At first Hythe thought the "Aphrodite" had been hulled in the for’ard compartment. He expected to see the submarine settling by the bows, and it was to his surprise and relief to find that such a catastrophe had not occurred. When he came to the after bulkhead watertight door he found it secured. To attempt to open it would probably jeopardize the safety of the vessel, and Hythe was too good a sailor to tamper with the securing bars. "Might have known that," he growled. "Now, what’s to be done." Another thud, this time to starboard, made the "Aphrodite" tremble again, but there was no disconcerting heel following the shock. Hythe had no doubt about it; the concussions were caused by explosions, either of torpedoes or floating mines, outside the vessel. "I wonder how many of these she’ll stand?" he muttered, clambering up three or four rungs of a ladder and trying a manhole above his head. "Well, here goes. I’ll try this hatchway. The cover isn’t locked." Back slid the metal slab, and the sub saw that he had opened a means of communication with the after conning-tower. The place was in semi-darkness, only the subdued light from the pale green water filtering in through the observation scuttles. As the electric-light from the alley-way flashed upwards one of the occupants of the conning-tower glanced down and gave an exclamation of annoyance, adding:-- "Hurry up and cover that hatchway. How can you expect me to see ahead with that glare under my eyes?" "Sorry, Devoran," replied the sub, hastily skipping up the remaining portion of the ladder and replacing the cover. "Oh, it’s you, is it?" said the chief officer. "Sorry, I thought it was Polglaze. Can’t talk now. Stand here, if you will."