Slowly the _Hammerer_ glided astern for almost her own length; then, with a bang that was audible above the roar of the guns, the hawser parted. By the time the _Tremendous_ had checked her way and had re-established communication, twenty minutes had elapsed. Already the _Hammerer's_ top-hamper was little more than a tangled skein of steel. Her fore topmast had gone; her mainmast had been severed ten feet below the lower fighting-top. One of her funnels had gone by the board; the other was holed in twenty different places and looked little better than a sieve. Only the funnel-guys prevented it from sharing the fate of the former. Yet she kept up a heavy fire with unabated violence, while, to relieve the pressure of the Turkish batteries, two armoured cruisers closed and directed their attention upon the hostile guns. Suddenly Dick sprang to the wheel, unceremoniously pushing aside the coxswain, whose whole attention was centred upon the stranded battleship. "Full speed ahead both engines!" he shouted. His quick eye had discerned a suspicious swirl on the surface within a cable's length of the picket-boat's starboard bow. Even as the little craft shot ahead, from the centre of the disturbed water appeared a periscope. It was not the periscope of a British submarine, of that Dick felt certain. It was a hostile craft, about to take her bearings prior to discharging a torpedo at the motionless _Hammerer_ or her almost equally handicapped consort. "Stand by, men!" ordered the Sub. The picket-boat, having a dead weight of fifteen tons exclusive of the crew, was capable of dealing a heavy blow, but Crosthwaite realized that that would mean her own destruction. Already he had weighed up the situation. It was risking the lives of a mere handful of officers and men in an attempt to save the huge battleship and her complement of nearly eight hundred. With a heavy crash the keel of the picket-boat came in violent contact with a submerged object. It was something more substantial than the slender periscope, which, shattered by the impact, had vanished. For a moment the British craft seemed on the point of turning turtle; then, with a sickening movement, she slid over the obstruction into deep water. It was evident that the picket-boat would not survive the collision. The artificers, having taken steps to prevent an explosion of the boilers, abandoned the engine-room as the water rose above the beds of the engines. A minute later the crew were swimming for their lives. "She's off, sir," announced a petty officer who was swimming strongly by the side of the Sub-lieutenant. "They'll pick us up all right." The _Hammerer_, thanks to the efforts of the _Tremendous_, aided by her own engines going full speed astern, had shaken herself free from the dangerous shoal. Still replying briskly to the Turkish batteries, she glided into deep water, circled, and steamed slowly towards the spot where her picket-boat had disappeared.