"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." "It was in my power to do so," replied Captain Restronguet calmly. "But I refuse to do so in the interests of humanity. It is part of my creed that human life is sacred, and should not be sacrificed unless absolutely necessary." "But you vowed you would destroy the ’Vorwartz’?" "Most certainly. What I wanted to do, and what I will, I hope, eventually be able to do, is to play with that wretched counterfeit of my submarine, and drive von Harburg into a state of panic. Then as soon as I can pursue the ’Vorwartz’ into comparatively shallow water I will sink her--but if humanly possible, I will save her crew. Come on deck, Mr. Hythe. You will then be able to see how we tackle repairs of this description." The sub followed his host on deck, where about half of the crew were engaged in rigging up a pair of sheer-legs over the stern. At the same time the water ballast was being ejected from the ballast tanks in the sternmost section of the vessel, while the bow compartment tanks correspondingly filled. Lower and lower sank the for’ard portion of the "Aphrodite," while the after end rose out of the water till the blades of the polished propellers were exposed to view. From the head of the sheer-legs a double block was fixed, the tackle being brought to bear upon the damaged shafting. "We’re in luck, sir," shouted Kenwyn, who had lowered himself over the stern. "The metal is not fractured; it’s a length of tarred rope wound round and round the boss of the propeller." "Take axes and cut the rope through," ordered Captain Restronguet, addressing Carclew and Gwennap. "We’ll soon clear that."