"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."
"By means of the detectors. I can fix the position of the 'Vorwartz' to a nicety, and no doubt that scoundrel of a von Harburg can do the same, thanks to my invention, of which he basely availed himself. I suppose you know he let loose four torpedoes?"
"Yes; but it puzzled me to know why they exploded so far from the ship."
"The 'Aphrodite' can, when desired, be protected by a belt, as it were, of electric fluid, so long as she remains under water. Any explosion brought within that zone would be spontaneously ignited. It was a weak current that knocked all the stuffing out of you, when you were nearly run down at Spithead."
"Then, this submarine is practically invulnerable?"
"When submerged, yes. A mine or a torpedo cannot harm her, and at a depth of fifty feet she is out of all danger of being run down. On the surface she might, if perceived, be a target for a quick-firing gun, or she might be cut in two by a large, swiftly-moving steamer. Von Harburg, did he but know it, has a unique opportunity now our propeller shafting is gone; he might wait till we rose to the surface and then ram us."
"But why didn't you torpedo his 'Vorwartz'?" asked Hythe. "Your torpedoes would easily overtake that vessel."