"For goodness’ sake try the supplementary current!" exclaimed the chief officer anxiously, but the result was the same. The apparatus by which the powerful means of offence was controlled was out of order. Either the lightning or the shock of the impact of the "Vorwartz’s" stem had thrown the delicate mechanism out of gear. Nor could the torpedoes be used, for the tubes, having an arc of only four degrees on either side of the bows, could not be brought to bear upon the rival submarine. This time Karl von Harburg had scored heavily, and stood every chance of getting clear without the "Aphrodite" being able to revenge herself upon the submarine that had caught her napping. Meanwhile the crew of the "Aphrodite," after the first shock, had taken up their stations with consummate coolness. Every man knew that the damage was great, and that the "Vorwartz" was the cause of it. One chance yet remained for them to revenge themselves upon Karl von Harburg. Directly the "Vorwartz" backed out of the rent in her rival’s side, the "Aphrodite" might be able to turn sufficiently to discharge a torpedo. At the same time steps must be taken to prevent the stricken craft from sinking into depth where the pressure of the water would literally crush their as yet undamaged sections of the submarine like an egg-shell under a hundred-ton hammer. As soon as the water in the midship section rose to the level of the centre platform Devoran gave orders for the detachable keel of that compartment to be dropped. Kenwyn touched the emergency switch, and the massive dead weight fell. Relieved of this mass of iron the "Aphrodite" lurched in an effort to rise to the surface. The sudden strain wrenched her free of the bows of the "Vorwartz." Instantly the water, pouring through the greatly enlarged aperture, filled the whole of the centre compartment, and before the submarine had a chance to turn and let fly a torpedo at her antagonist, the "Aphrodite" sank slowly and surely. This, although serious, was a point in her favour, for Karl von Harburg, observing with savage glee the havoc he had wrought, concluded that his rival’s craft was sinking for the last time to the bottom of the Red Sea. Accordingly, satisfied that he was now free to pursue his piratical acts, since the "Aphrodite" was the only submarine he feared, he backed astern, rose to the surface, and proceeded in a southerly direction towards the Straits of Bab-el-Mandeb. Hardly a word was spoken as the "Aphrodite" sank. Devoran, his eyes fixed upon the depth gauge, was waiting his time. He, too, realized that should the submarine rise to the surface it would merely be giving her antagonist a unique opportunity of holing another of the sections that as yet remained intact. On the other hand, he had to guard against the danger of descending too far.