Meantime the guns on the shores back of the harbor were pouring their shot at the black target in the moonlight, and the din was terrific. Word came to Hobson that some of the torpedoes could not be fired, as their cells had been broken. The order was given to fire the others, and the fifth exploded promptly, but the remaining ones had been shattered by Spanish fire and were useless. The commander knew that under these circumstances it would take some time for the _Merrimac_ to sink. The important point was to keep the ship in the center of the harbor; but the stern-anchor had already been cut away. Hobson watched the bow move against the shore-line. There was nothing to do but wait and see where the tide would swing them. The crew now gathered on deck. One of them, Kelly, had been dazed by an exploding shell. When he had picked himself up he started down the engine-room hatch, but found the water rising. Then he remembered the _Merrimac's_ purpose, and tried to reach the torpedo of which he had charge. The torpedo was useless, and he headed back to the deck, climbing up on all fours. It was a strange sight to see him stealing up, and Hobson and some of the others drew their revolvers, thinking for the moment that he must be an enemy who had boarded the ship. Fortunately they recognized him almost immediately. The tide was bearing them to the center of the channel when there came a blasting noise and shock. A mine had exploded beneath them. "Lads, they're helping us!" cried the commander. But the mine did not break the deck, and the ship only settled a little lower. For a moment it seemed as if the coal might have closed the breach made by the explosion, but just as the crew feared that they were to be carried past the point chosen for sinking the current from the opposite shore caught them, and the _Merrimac_ settled crosswise. It was now only a matter of time before she would sink in the harbor.