"Merely a precautionary measure to clear the holding plates of mud and seaweed," explained Captain Restronguet. "If the spades, as I might term them, do not fold absolutely flush with the vessel’s bottom, there’s bound to be a tremendous resistance to the water and consequently a serious loss of speed. Now the jet is turned off. Listen again and you will hear the anchor plates come home." "That they are!" exclaimed the sub, as a distinct thud shook the plates under his feet. "I suppose they are lifted by metal rods working in water-tight glands?" "Oh, no; merely by the attraction of electromagnets. Every valve and door in this vessel is electrically controlled, although in some cases, such for instance the hatch by which we gained this compartment, manual power can be used. When next an opportunity serves I will show you the engine-room, but we are about to rise now. I must go to the for’ard conning-tower. You may come, too, if you feel inclined, or if you prefer there is a private cabin at your disposal." "How does the submarine rise, might I ask? By means of horizontal rudders?" "Yes and no," replied Captain Restronguet. "But before I explain perhaps this might interest you." Stepping over to where three levers stood in the centre of the compartment the captain thrust one hard down. Instantly a portion of the floor opened. Another lever caused a corresponding part of the outer plating to slide back, revealing an observation plate of about three feet by two through the double skins of the starboard bilge-plates. "I can see nothing," said Hythe, as he strove to peer through the glass. "It is perfectly dark." "There ought to be sufficient light at this depth to see fairly well, but since the ’Aphrodite’ is still on or nearly on the bottom of The Narrows, the hull intercepts what little light there is to penetrate the water. Now look!" Touching a switch Captain Restronguet caused a strong search-light to shine vertically downwards. About a fathom of water lay between her keel and the floor of the sea. She was slowly moving under the influence of the young flood tide. The bed was shelving steeply from one hundred and twenty feet to less than ninety. Hythe could see the seaweed waving in the current and the fash, mostly of the flat-fish tribe, darting rapidly towards the dazzling light. "What’s that?" he asked, as two objects, resembling barnacle-covered pipes passed slowly across the field of light. "Telephone cables between the Victualling Yard and Mount Edgcumbe," replied his companion. "If I felt inclined, what is to prevent me from sending out a man and tapping those wires? All submarine cables are entirely at my mercy. If I wished I could create a greater panic than the Stock Exchange, the Bourse, or Wall Street ever yet experienced. But I must switch off the light and close the panels now. I am wanted in the conning-tower."