Once he thought he heard something that sounded like shots and he stopped short in his tracks. His old eyes, keen yet, despite his years, looked eagerly around. But as far as his eyes could reach there was nothing to be seen, and he came to the conclusion that he must have imagined the sounds or that they were caused by some rumbling of the earth. In a surprisingly short time, the captain was back, panting and winded by his exertions. "Well," asked Tyke eagerly, "did you find out anything?" "The men were all huddled down on the shore evidently scared out of their wits. I guess we can cross them off our slate. But how about you? Did you find any clue?" "Nary a thing," answered Tyke dejectedly. "I thought at one time that I heard shots, but when I come to look it up there was nothing in it." "We must find them!" cried the captain excitedly, pacing back and forth like a wild animal and digging his nails into his palms as he clenched his fists in anguish. "We'll go over every foot of this island. I'll get out every man on the ship and set him to work searching." "I wouldn't do that--at least not yit," adjured Tyke, laying his hand on the captain's arm. "Of course we may have to do that as a last resort. But you know what sailors are, an' we don't want to have 'em cracking their jokes 'bout Allen an' Ruth going off together. Wait a bit. The day's young yet an' they may turn up any time of their own accord. In the meantime, we'll explore places that we haven't tried before an' mebbe we'll run across 'em. If everything else fails, then we'll turn out every man jack of the crew and go over every inch of the island." To the agonized father, everything that savored of delay seemed intolerable, but he yielded to the wisdom of Tyke's suggestion and once more they started out in their desperate search. CHAPTER XXV THE LAKE OF FIRE Drew was all animation in an instant at the new hope that sprang up within him with its offer of possible safety for his companion and himself. "Why didn't I think of it before?" he repeated, his voice shaken with excitement. "You didn't think of it before, because you were working like a slave. No man can work like that and think of anything but what he is doing. Oh, Allen, won't it be great if you are right?" "I'm going to see if I am right," he replied. "How can you tell?" she asked divining that he was fumbling at his pocket. "In this way," he answered, drawing out the oilskin bag that contained his precious matches. He struck a match and held it aloft. At first the flame mounted straight up in the air. Then an instant later it was deflected and stood out at a distinct angle from the stick. "See," cried Allen jubilantly. "There's a current of air in the cave. It's too slight for us to feel, but the flame feels it. If we were sealed up utterly in the cave, the air would be still. Somewhere the air is coming in from the outside world and it's up to us to find out where."