"We've fouled something, sir," reported the Acting Sub-lieutenant of the submarine, a youngster but recently promoted from midshipman. "By Jove, we have!" agreed his superior officer, as he glanced through the small observation-scuttle in the side of the conning-tower. "Awkward--confoundedly awkward!" He was seriously annoyed; not at the immediate danger, but at the failure of his device to ward off obstructions; for in ascending the submarine had risen immediately underneath the anchor-chamber of a mine that had broken adrift, but still retained the metal box containing the depth-regulating mechanism. The anchor-chamber had engaged on the inside of the starboard girder, and what was more, a length of loose rope had trailed aft and was almost within the sweep of one of the twin propellers. In another few seconds the rope would be wound round and round the boss as tightly as a steel hawser. Promptly the electric motors were switched off. For the time being one danger was averted. It remained to shake the submarine clear of the powerful charge of explosive that was hitched up within seven feet of the conning-tower. One slight tap on one of the many sensitive "feelers" of the mine would result in the total destruction of the submarine and her daring crew. "Flood auxiliary ballast-tanks," ordered the Lieutenant-Commander. Slowly, as the water hissed into the strong steel compartments, the submarine sank in a vertical direction. For the nonce her diving-rudders were useless. She was stationary as far as movement in a horizontal direction was concerned. The officers anxiously watched the hand of the steel indicating the depth. At twelve fathoms the downward movement ceased. The Lieutenant-Commander had hoped that the buoyancy of the mine would release the anchor-chamber from the steel girder that in this instance had proved to be a source of danger rather than a protection; but no--the submerged vessel had drawn both anchor-chamber and mine beneath the surface. "Prepare to anchor--let go!" With a sullen roar, intensified by the confined space, the stockless anchor was released from its "housing" at the for'ard end of the keel. Suddenly the studded-linked cable "snubbed" as the flukes obtained a hold; then, anchored at fifteen fathoms beneath the surface, the submarine fretted easily at her cable in the five-knot current. Again the Lieutenant-Commander peered through the scuttle. At that depth the light that filtered through the water was just and only just sufficient to enable him to discern the deadly object still clinging tenaciously to the submerged craft. Under the action of the current it tilted ominously, though fortunately not sufficiently for any of the projecting "feelers" to come in contact with the metal plating of the anchored submarine.