It heard their propellers thrashing, and they made, to be sure, a very fine noise. But the Wabbler quivered with eagerness as somewhere within itself it noted a vast variation in the vertical magnetic component, which increased and increased steadily. That was the warship moving very slowly out of its place in the drydock. It moved very slowly but very directly toward the Wabbler, and the Wabbler knew that its destiny was near.
Somewhere very far away there was the dull, racking sound of an explosion. The Wabbler may have realized that another of its brothers had achieved its destiny, but paid no heed. Its own destiny approached. The steel prow of the battleship drew nearer, and then the bow plates were overhead, and something made a tiny click inside the Wabbler. Destiny was certain now.
It waited, quivering. The mass of steel within the range of its senses grew greater and greater. The strain of restraint grew more intense. The tick-tick-ticking of the Wabbler's brain seemed to accelerate to a frantic—to an intolerable—pace. And then—
The Wabbler achieved its destiny. It turned into a flaming ball of incandescent gases—three hundred pounds of detonated high explosive—squarely under the keel of a thirty-five thousand-ton battleship which at the moment was only halfway out of a drydock. The water-tight doors of the battleship were open, and its auxiliary power was off, so they could not be closed. There was much need for this drydock, and repairs were not completed in it. But it was the Wabbler's destiny to end all that. In three minutes the battleship was lying crazily on the harbor bottom, half in and half out of the drydock. She careened as she sank, and her masts and fighting tops demolished sheds by the drydock walls. Battleship and dock alike were out of action for the duration of the war.
And the Wabbler—
A long, long time afterward—years afterward—salvage divers finished cutting up the sunken warship for scrap. The last irregularly cut mass of metal went up on the salvage slings. The last diver down went stumbling about the muddy harbor water. His heavy, weighted shoes kicked up something. He fumbled to see if anything remained to be salvaged. He found a ten-foot, still-flexible tail of metal. The rest of the Wabbler had ceased to exist. Chronometer, tide-time gear, valves, compressed-air tanks, and all the balance of its intricate innards had been blown to atoms when the Wabbler achieved its destiny. Only the flexible metal tail remained intact.
The salvage diver considered that it was not worth sending the sling down for again. He dropped it in the mud and jerked on the lifeline to be hauled up to the surface.