“This,” returned the scientist: “the mysterious force which is holding your engines, which prevents us opening the door, and has also jammed the steering gear, is the same power that causes the needle of the compass to point to the north!” The inventor stared in amazement. “Then what hope have we of ever getting away?” he asked at length. “None whatever,” was the reply, and at that Garth relapsed into silence. Each man was busy with his own thoughts, each was striving to find some way of escape from the perilous situation in which they found themselves; but, try as they might, no gleam of hope presented itself. The vessel on which their very existence depended was helpless as a log in the grip of the giant natural forces of the magnetic mountain; and, added to this, was the ever-increasing peril from the crater, which was now flinging out a veritable cataract of glowing stones, to the accompaniment of numerous awe-inspiring explosions. “I’m afraid it’s a case,” Seymour said at length. “Twenty-four hours will see the last of this expedition, unless the sulphur cloud lifts so that we can get some air. How long do you reckon the air will last, Garth?” The inventor’s answer was drowned in a thunderous detonation, which shook every plate in the _Seal’s_ hull. The side of the cone above her burst open, and a torrent of glowing lava, leaping forth, plunged downward towards the lake. For an instant it seemed as though the ill-fated submarine would be overwhelmed; but, changing its course at the last moment, with a deafening roar the lava river emptied itself into the lake. The uproar which followed baffles description. A series of fearful reports rang out as the two elements met, and the maddened waters, driven backwards for a moment by the fury of the molten torrent, rolled shoreward once more in one tremendous wave, beneath which, for a short time, the _Seal_ was completely submerged. The water hissed and boiled as it poured over the cooling lava, and a cloud of sulphurous vapour rolled upward from the surface of the lake, to lose itself amid the whirling wreaths of the brooding cloud above. The heat became terrible as the time went on. The atmosphere of the boat was like that of an oven, and great beads of sweat poured off the watchers, as they stood, with straining eyes and haggard faces, gazing on all the awful grandeur of the eruption. Their furs they had long since laid aside, and, ere long, their jackets followed; but the feeling of oppression seemed to lessen not a whit. Their tongues were dry as parchment, despite the copious draughts of water with which they attempted to slake their thirst. The food which Garth had prepared lay untasted on the saloon table; for their terrible situation had, for the time, at any rate, driven all thoughts of eating from the explorers’ minds. The engineer was still below, striving even yet to discover the cause of the--to him--inexplicable behaviour of his engines.