Above rose the heights of the barrier range, towering peak above peak for thousands of feet into the splendour of the Arctic sky; before him, silent and deserted as a sea of the dead, rolled the mighty waters of the Polar Sea. “Glorious!” breathed Mervyn rapturously. “Glorious!” and he shaded his eyes from the glare of the sun, as he gazed in an ecstasy of enthusiasm across the shimmering wave-crests. Then, from far away, came a low, rumbling roar, as of distant thunder. “What was that?” the scientist asked sharply; “not thunder, surely?” “Hardly,” returned Seymour; “but now let us turn in for a spell. It’s been over forty-eight hours since we had a wink of sleep.” “You’re right, Seymour,” admitted the scientist; “do you all go below for an hour or two. I will take the watch; I cannot sleep until I know the result of our quest.” Despite the persuasions of his comrades, the Professor’s determination remained unshaken, and at length they left him and went below. For an hour Mervyn paced the deck excitedly, listening to the thunder-like detonations, which rolled up at frequent intervals from the far horizon; then, for the first time, he became conscious that the vessel was quivering beneath him, as though in motion. He glanced astern. The _Seal_ was straining at her cable like a thing of life! “The current must be strong,” he exclaimed to himself, and walking aft he tried the lashing of the rope. It was secure, for the American was an adept at knotting. Retracing his steps, Mervyn leaned against the rail and fell into a reverie. What could there be beyond? he thought. Was there a great island in the midst of this sea, an undiscovered realm whose forests afforded refuge to strange animals, or perhaps stranger men? The deserted sea around seemed to give little hope of this. Surely, if there were habitable land within the Arctic circle, within the confines of the barrier ice, some flying creature would be visible; some seafowl would be disporting itself above the waters, or diving for its food beneath the curling crests of the sparkling waves? But no sign was there of bird; not even a seal furrowed the lifeless waters. _Crack!_ A pistol-like report startled Mervyn out of his abstraction. _Crack!_ Again it sounded, from directly overhead, and the Professor looked up quickly. A thin, dark line was spreading rapidly along the face of the ice-cliffs, and even as he gazed it widened, and a huge mass of ice, thousands of tons in weight, leaned outward. For an instant it hung poised, then thundered downward. The enormity of the peril appalled Mervyn! He stood as one spellbound. It seemed as though naught could save the _Seal_ and her crew from utter destruction; yet, in the very instant of her dire peril, deliverance came in a marvellous manner. There came a sharp snap from the stern, and the _Seal,_ leaping forward like hound from leash, passed clear beneath the huge, descending mass, and sped seaward. Her cable had parted!