"Get Lieutenant Mackinson and those boys," the captain continued, and the ship's surgeon started down the stairway to find that Joe and Jerry already were summoning Slim and the lieutenant. "It looks as though we'd caught the man," the doctor whispered. As the four reached the deck where the captured man stood between the first assistant engineer and the captain, who had by this time taken out his revolver, there was a gasp of astonishment from Joe, followed by a louder "Holy smoke!" from Slim. "Do you recognize this man?" the captain asked in a sharp tone. "I should say I do, sir," Joe responded. "_He is the man who was planting ammunition in the waters near the navy yard that night before we sailed_!" "The very same one, sir!" Slim exclaimed, with equal positiveness. The ship's surgeon, who had followed the others upon deck, stepped closer for a better inspection of this enemy. At the same instant the prisoner, striking out with both hands, knocked the captain's revolver hand into the air, and thrust the engineer from him. Before anyone could interfere he was dashing down the deck toward the stern. Just as he took a wild, headlong leap over the rail the captain fired. While the captain, through a speaking tube, was instructing the man in the pilot house to signal below "Reverse engines," the others rushed to the stern of the ship. Far behind them in the foamy trail left on the moonlit water by the vessel they saw what seemed to be the head of a man bobbing up and down--and then it entirely disappeared. The ship was turned, and that portion of the sea searched, but without avail. "Gone," said the captain in tones of very evident relief. "Well, it was death for him, one way or another, and he took his choice." As the captain and surgeon moved away from the stern rail of the _Everett_, the three lads and the lieutenant still stood there, gazing far out to sea. "The man who made me nearly freeze to death in the water," spoke Joe, as though thinking aloud. "And pummeled my stomach until it was sore for three days," echoed Slim, in sad reminiscence. "And made me run a mile in nothing, flat," added Jerry. "And fought me to a knockout finish later," mused Joe. "And nearly smothered me to death," spoke the lieutenant. "And was finally corralled by an Irish engineer!" said Slim. "Gone," concluded Jerry, "and no one here will mourn his departure." CHAPTER IX THE PERISCOPE AT DAWN That night the boys had ample evidence that they were inside the submarine zone, where anything might happen at any minute. Not a light was permitted on any of the ships, and they traveled along in the most peculiar fashion and over the most irregular course, never going at more than half speed and not more than a mile or so without a complete change of direction.