The quartermaster telegraphed for speed to be reduced; the submarine turned towards the deeper Smeaton Pass, leaving the destroyer, in blissful ignorance of the proximity of the much-searched-for Captain Restronguet, to take the short cut into the Hamoaze.
"Now we can take things more easily," observed the captain after awhile. "The channel is now ninety feet deep, although we are but a few hundred yards from Plymouth Hoe. We are now approaching the Drake Channel, between the Victualling Yard and Drake's Island."
"However do you contrive to find your way about in a complicated waterway like this?" asked the sub, who was well acquainted with the above water navigation of that part of Plymouth Sound within the Breakwater. "You have no periscope?"
"A periscope would soon give the show away," observed his companion. "For the present, we simply rely upon the chart and compass, and look out for the sudden shelving of the bottom. See, there! Hard a starboard, quartermaster: there's the Vanguard Bank dead ahead."
From almost due south the "lubber's line" in the compass-bowl pointed to almost due north. The "Aphrodite" had reached the "Narrows" between the Devil's Point and Cremyll.
At a word from Captain Restronguet the quartermaster set the engine room telegraph indicator to stop; another movement, a gentle hiss betokened the admittance of water into one of the sub-compartments of the vessel. Then slowly and mysteriously the "Aphrodite" sank in twenty-two fathoms of water to the bed of the narrow channel.
At that depth, and owing to the swift-running tide, charged with the mud brought down by the River Tamar, the water was so thick that, till the electric lamps were switched on, the submarine was in total darkness.
"Prepare to anchor," ordered Captain Restronguet through a telephone.
"Good!" he ejaculated, after about a minute had elapsed. "Now, Mr. Hythe, you must be feeling hungry; so will you do me the honour of having lunch in my cabin?"
CHAPTER VIII.