As the sub followed his companion he could not help noticing the freshness of the atmosphere. Compared with the nauseating reek of the submarines he had served in the interior of the "Aphrodite" was as wholesome as could be. There was, moreover, a sting in the atmosphere that recalled the health-giving breezes of the Scottish moors. "All right, Mylor, you carry on," exclaimed the captain to the helmsman in the conning-tower. "Starboard your helm a bit--go!" Forty feet beneath the surface the submarine swung round the sharp band formed by the high ground of Cremyll and Mount Edgcumbe. Close to the heavy mooring-chains to the south of the Rubble Bank she glided, till her course, almost due north, lay right up the land-locked Hamoaze. "Why, we’re going up the River Tamar!" exclaimed Hythe, glancing at the compass. His knowledge of the intricacies of Plymouth Harbour and the Hamoaze, and the compass course told him that, for nothing was to be seen through the conning-tower scuttles save an expanse of pale green water. "Yes, that is so. I am just running up to Saltash in order to pick up a man returning from leave," replied Captain Restronguet with a laugh. He spoke as casually as if he were the coxswain of a British battleship’s liberty-boat. "We are now passing the South Yard of Devonport Dockyard. But excuse me, I have something to attend to in the after conning-tower. You won’t mind remaining here, I trust? Keep her as she is, Mylor; I am going to reduce speed to five knots or even less." Hythe sat down on a folding seat fixed below the port scuttle, whence he could see either ahead or on his left. The helmsman’s head and shoulders obstructed the view to starboard. It was fascinating work watching the sea swirl past, and noting the changes as the "Aphrodite" passed through patches of various coloured water, for the tide was beginning to stir up the dark brown sediment brought down from the Devonian Hills by the swift-running Tamar, and the result was a constant kaleidoscope. But after a while, finding that nothing else was visible, the sub transferred his attention to the interior of the conning-tower. Presently a bell gave forth a warning note and the helmsman promptly touched a lever. The depth according to the gauge diminished to less than thirty-five feet. "Is that an automatic sounding machine?" asked Hythe. Mylor, still keeping his eyes fixed in front of him, shut his lips tightly, and Hythe, thinking that he had not caught what had been said, repeated the question. "Cannot say, sir," said the helmsman decidedly. "It’s against orders. For any information ask the cap’n." "That’s a staggerer," thought the sub. "One thing about it the fellow’s true to his master." Meanwhile Captain Restronguet had retired to his cabin, where he drafted a communication to the Commander-in Chief of the Devonport Command. This done, he ascended to the after conning-tower where two seamen were on duty.