"The detector is sensitive to anything of that nature within a hundred and twenty miles, but, of course, the actual position of the chase cannot be fixed with any degree of accuracy at that distance. But as soon as we approach within twenty miles of von Harburg’s counterfeit presentment of my submarine, the position of the ’Vorwartz’ will be accurately recorded on the chart controlled by the electric detector." During lunch the wireless room reported that a vessel was sending out calls for urgent aid, and in response to a request for further details came the startling news that the Dutch liner, "Noord Brabant," had been forcibly boarded by the crew of the "Vorwartz" fifteen miles due east of Wadi Jemel. Several of the Dutchmen had been wounded when attempting to resist; the strong-room had been forced, and nearly ten thousand pounds worth of gold had been removed. Not satisfied with this, Karl von Harburg discharged a torpedo at the ill-fated "Noord Brabant," which, exploding under her starboard quarter, completely flooded the after compartments. Leaking badly, for the shock had strained the water-tight bulkheads, the liner headed slowly for Sherm Sheikh, an inlet in the mainland, where her captain hoped to run her aground on the mud and sand that form the bottom of the cove. "Here we are," exclaimed Captain Restronguet, running his finger over the chart of the Red Sea. "Ninety miles from Wadi Jemel; three hours run at our maximum speed. Keep her going for all she’s worth, Kenwyn. I’ll be with you in the conning-tower in less than ten minutes. Let the ’Noord Brabant’ know we’re on our way, and keep me informed of how she’s progressing." While the "Aphrodite" tore on her errand of mercy, Carclew was keeping vigilant watch upon the electric detector; but, to the disgust of all on board, instead of the "Vorwartz" making her presence felt more strongly the sensitive current grew more and more feeble. Was it possible, then, that the "Vorwartz" was able to attain a much greater speed than her rival, and in consequence slipping farther and farther from the doggedly-pursuing avenger? Just as Captain Restronguet, accompanied by his guest, was about to proceed to the conning-tower, a final message came from the ill-fated "Noord Brabant"--"Sinking; are taking to the boats." But the "Aphrodite" was not the only vessel hurrying to the rescue. The P. & O. Liner, "Persia," a magnificent internal-combustion propelled ship of 40,000 tons, that had been built to "knock spots off" the largest North German Lloyd boat on the Australian route, was returning on her maiden voyage. Warnings of the presence of the "Vorwartz" had been given her. Her cargo was a precious one; moreover she carried His Majesty’s mails; but at the urgent call of distress all other considerations were set aside.