With a bound he leapt to the stairhead, and darted down to the engine-room. Thrusting over the lever to the last notch, he dashed back again into the wheelhouse, just as the _Seal,_ straining under the full power of her engines, snapped her mooring cable like a cotton thread and sped seaward. Past the raging reptile she flashed like a meteor, and for a few moments the engineer’s heart bounded with hope that the giant brute would not give chase. But not so easily was the ichthyosaurus shaken off. With a sweep of his tail he turned and swung after the flying vessel. Fast as the submarine was travelling, it soon became evident that the reptile could travel faster. With a few powerful strokes he drew alongside, and his mighty teeth snapped within an inch of the vessel’s rail, Wilson turning the _Seal_ only just in time to avert disaster. This temporary failure appeared to increase the reptile’s rage, and he swept forward again like a flash of light. Four walls of green, foam-capped water poured from his thrashing paddles, and washed clear over the submarine’s deck. The monster’s tail, swinging, rising, and falling, lashed the water with strokes that rang like the reports of guns. Something must be done, and that quickly, Wilson thought. But what? That was the question. If that swinging tail once smote the _Seal,_ her course would be ended on the instant. Stout as were her plates, they could not stand a blow of that sort. Glancing desperately about him, the engineer’s eye fell upon Seymour’s elephant gun. It was a forlorn hope, yet, in his desperate plight, he determined to try a shot with the great weapon. Giving a turn to the wheel, to alter the course of the vessel, he locked it, then took down the gun. It was loaded, for, since the octopus’s attack, Seymour had insisted on its being kept ready for action; so, opening the door cautiously, Wilson stepped out. The rush of water, knee-deep, almost swept him off his feet, but, bracing himself against the wheelhouse, he raised his weapon and aimed carefully at one of the moonlike eyes of his pursuer. _Bang!_ The kick of the great gun almost dislocated the lad’s shoulder, but the pain of this was as nothing compared to his chagrin when he found that he had missed. The terrific speed of the vessel and of her mighty enemy made aiming exceedingly difficult, and, added to this, the elephant gun was a weapon to which Wilson was entirely unaccustomed. Once more he raised it to his shoulder, and fired the second barrel. This time the shell struck the reptile’s head, but glanced off the gleaming scales without exploding. “The brute must be made of steel,” the engineer muttered savagely as he retired, disheartened by his failure. As the net result of his effort he had succeeded in still further enraging his huge opponent, and had badly bruised his own shoulder. The floor of the turret was awash when he entered, but he cared little for a discomfort of so trivial a character.