Devoran indicated a place on his left, so that Hythe could see out of the for’ard and port scuttles. It was some time before his eyes grew accustomed to the half-light; then by degrees he saw that the "Aphrodite" was tearing through the water at a great speed. A hundred feet in front of him he could discern the fore-conning-tower, and beyond that nothing but water that faded into extensive gloom. No sign of the "Vorwartz" was to be seen. Hythe stood and waited. Without doubt the "Aphrodite" was in chase of the rival submarine, so that the latter had attempted strong measures to beat off her pursuer, but the absence of anything to be seen came somewhat like a disappointment to the young naval officer. Suddenly there was a wild disturbance in the water less than twenty yards abeam. Again the sickening concussion even more noticeable within the conning-tower than down below. "Torpedo!" ejaculated Devoran. He had no time for further explanation, and Hythe was at a loss to understand how the dangerous missile had exploded without actually coming into contact with the metal plating of the submarine. "What’s that, by smoke!" ejaculated the chief officer, as in place of the almost inaudible purr of the motors came a most discordant clanging, jawing, and groaning of machinery, while by observing the compass Hythe saw that the "Aphrodite" was describing a wide circle to starboard. "You’ve buckled one of your propeller shaftings," said the sub. "I’ve had some before. I know what those noises mean." "I hope not, by Jove!" replied Devoran, and almost at that moment the telephone bell operator from the motor room rang. "You’re right," continued the chief officer. "It is the propeller shaft; we’re knocked out for the time being." Captain Restronguet remained in the fore conning-tower till the indicator of the detector showed that the "Vorwartz" had put a safe distance between her and her pursuer; then leaving the course in the hands of a quartermaster, he gave orders for the "Aphrodite" to be brought to the surface. Hythe would have forborne to question the captain at such an anxious time, but to the former’s surprise Captain Restronguet hailed him quite genially and in a manner that showed no trace of his annoyance at being temporarily baffled. "Well, Mr. Hythe, wherever have you been?" he asked. "I thought you were following me when I left the cabin, and never missed you till ten minutes ago. You see, I had to keep all my attention on what was going on." "You said nothing about my accompanying you, sir," replied the sub. "As a matter of fact I took the liberty of going up into the after conning-tower." "That was better than remaining below," agreed Captain Restronguet. "Only there was not so much to be seen. From the for’ard tower we caught sight of the ’Vorwartz’ on two occasions." "I should have thought you had her in sight the whole time, sir," remarked Hythe. "Otherwise I cannot see how you kept in her track."