But the way was rougher now, and at one place they had to make a long detour. But they made no complaint. As long as no impassable barrier of rock loomed up before them they could feel that they were getting nearer and nearer to freedom and life. But before long both became conscious of a steadily-growing heat in the air of the cave. The perspiration flowed from them in streams. At first they were inclined to attribute this to their strenuous exertions and the mental strain under which they were laboring. "Strange it should be so frightfully hot," remarked Drew, as he stopped for a moment to wipe his brow. "It's no wonder," responded Ruth. "It's hot enough on this island even when you're in the outer air, and it would naturally be worse still in this confined place." "But we didn't feel that way ten minutes ago," objected Drew. "We've done a good deal of walking since then," said Ruth, though rather doubtfully. "But let's get along, Allen. I'm just crazy to get to the outlet." They were about to resume their journey, when a great flame of fire leaped to the very roof of the cave about a hundred yards in front of them. They stopped abruptly, and in the smoky light of the torch both of their faces were white as chalk, as they faced each other with a question in their eyes. "Fire!" gasped the man. "Yes," assented Ruth quietly but bitterly. "What we thought was daylight is nothing other than fire." "Shall we keep on?" debated Allen. "We're so close that we might as well," advised Ruth. "Perhaps we may be able to get around it somehow." They went forward, though with excessive care, and a moment later stood on the brink of the most awe-inspiring spectacle they had ever witnessed. In a deep pit perhaps six hundred feet in circumference was a lake of liquid fire! The molten lava twisted and writhed as though a thousand serpents were coiling and uncoiling. A vapor rose from the fiery mass that glowed with a hideous radiance in all the colors of the spectrum. At intervals, huge geysers of living flame spurted up from the surface to a height of many feet and fell back in a glistening of molten gold and coruscating diamonds. It was a scene that if it could have been viewed with safety would have drawn tourists in thousands from every corner of the globe. But to the two spectators the thought that they were looking on one of the marvels of the world brought nothing but desolation and despair. "This must be the source of the lava flow when the whale's hump is in eruption," said Drew in a toneless voice. "I suppose so," said Ruth in a voice that for dreariness was a replica of his own. "Do you think it's possible for us to get around it in any way, Allen?" "Not a chance in the world," answered Drew. "You can see that the passage we followed ends at the brink of the crater. From there on, there's just a wall of solid rock. The only thing left for us to do is to get back to the place where the cave split into three parts."