“He has deserted us,” said the professor, after calling for the negro to come back. “Even the offer of five dollars per day in gold couldn’t hold him after such a sight.” “But I am not going to turn back,” said Mark, with set teeth, and he strode on, with Frank beside him; and the others followed. It was hard walking and climbing, and frequently they had to pause to get their breath. The air seemed to grow more suffocating as they drew nearer to the volcano. “It is the gas,” said Professor Strong. “I think we had better go back.” And he shook his head doubtfully. “There are the ruins of a village!” exclaimed Sam, pointing to a hill on their left. “That must be Frodamalos.” Without replying Mark led the way toward the spot pointed out. They had to cross a bed of lava and mud that was still warm, and then leap a wide ravine before they could get close to the wreckage of huts and houses. “Not a person in sight, nor a dead body,” remarked Frank, as they gazed about them. “That looks encouraging. Everybody here evidently got out before the big explosion.” “Let us go a little closer to the volcano, now we are here,” suggested Sam. “I don’t believe there is any immediate danger of another outburst.” The sight of the lofty mountain, with its smoke and vapor, was a fascinating one, and cautiously they moved forward once more until they could see the openings and the streams of lava quite plainly. The top of the mountain appeared to be split into several sections, and at one point they could see a ruddy glow that betokened a vast fire beneath. “Come, let us go back,” said Professor Strong, decidedly. “This is far too dangerous. We have seen enough.” And he caught Mark and Frank by the arm. “Look! look!” cried Darry, pointing with his hand. “The fire is growing brighter!” “And the lava is beginning to flow again!” ejaculated Sam. “You are right, professor, we had best get away from here!” All looked back and saw that Sam was right. The lava was beginning to flow from two of the vents in the mountain top. It was a steaming, hissing and dangerous looking mass, and began to move down on both sides of them. “We must run for it!” exclaimed Professor Strong. “If we do not that lava may cut off our retreat. Come!” And he set off, with all of the boys around him. It was no easier to descend the mountainside than it had been to come up. Rocks and loose stones were numerous, and it appeared to them that some of the cracks in the surface were wider than before. Once Darry stumbled and fell, and the wind was knocked out of him so completely that the others had to help him up and hold him for a moment. Then they turned in the wrong direction and encountered a bed of half-dried mud into which they sunk up to their shoe tops. “Hi! this won’t do!” called out Sam, who was in the lead. “We’ll all be stuck like flies on flypaper. We’ll have to go to the right.” And this they did.