Sub-lieutenant Fox, who was standing by the firing-key, needed no orders. His fingers pressed the ebonite disc. A hundred yards astern of the Capella a column of water was flying high in the air, followed by a tremendous roar. For one minute the vessel rocked violently in the agitated waters, then, circling, she made for the spot under which the explosion had occurred. With a splash a mark-buoy was dropped overboard to indicate the position of the shattered U-boat. By this time the torpedo-boats had arrived on the scene.
"A deuce of a commotion on shore, Barry," exclaimed the skipper.
"I should be surprised if there were not, sir," replied the Sub. "The racket was enough to smash every window within a couple of miles of the beach. They're signalling, sir."
"German submarine's boat rowing off. Intercept her," was the signal spelt out by the long and short flashes.
"More work," remarked Barry. "It's like looking for a needle in a bottle of hay. Shall I order the searchlight to be run, sir?"
"Very good," replied Captain Syllenger. "But before you do so you might signal to Hurst, and request that all available search-light be brought to bear in this direction."
Soon the hitherto pitch-dark sea was flooded in a blaze of light. Giant beams from the Isle of Wight shore joined with those of Hurst Castle to sweep slowly across the waves, supplementing the twin rays projected from the two search-lights on the Capella's bridge.
It was indeed a brilliant spectacle. The Capella and the torpedo-boats seemed outlined in silver. Along the shore as far as Hengistbury Head, the low line of cliffs was thrown into strong relief against the dark background of sky. The crest of every wave seemed as if made of delicate filigree work. Nothing afloat could hope to escape detection within the radius of action of the concentrated millions of candle-power search-lights.
Less than a mile away, and about the same distance from shore, a small black object bobbed buoyantly upon the waves. It was the ill-fated U-boat's canvas dinghy, apparently empty.
Down bore the Capella, her search-lights fixed upon the object of her search. The boat was not deserted. Lying at full length on the bottom boards were two men, who had adopted that position, in the vain hope of escaping detection.