"It's stopped snowing!" announced Mark, going to the entrance of the cave, "and it's much colder. I guess we'll stay here a while." He returned to his companions. They all went as far to the rear of the cave as they could, for the wind came in the wide entrance. "We must make a winding passage, and then the breeze can't find it's way in," suggested Jack. "I think--" But what he thought he never told, for at that instant the floor of the snow cave gave way right under where they were all standing, and the whole five of them went slipping, sliding and tumbling down, they knew not to where. For an instant all were so surprised and frightened that they could not even cry out. They were plunged into dense blackness. "What has happened?" Jack cried. Before any one could answer him, the blackness gave way to a glare of light, and the two boys, with Dirola and the men, brought up suddenly with a jolt on the floor of a big ice cavern. It was several hundred feet long, and as many wide, with a roof fifty feet above their heads. The sides were of pure ice, but, strangest of all, was the rosy, golden glow that filled the whole place. With wonder in their eyes the adventurers gazed at the source of the illumination. At one end of the cavern was a rude altar. Behind it, and on both sides, there arose great streamers of fire, tongues of flame, red, green, blue, purple, yellow and glaring white. Yet the fire did not burn, for there was ice on every side, and the ice did not melt. In wonder the crew of the _Monarch_ gazed. Presently from the other end of the cave there sounded a wild, weird song. It was like a chant. Then, before the adventurers could get to there feet, there filed into the cavern two score of men, all dressed in white fur. At the head of the procession marched two men who were veritable giants, compared to those about them. They bore between them, on a rude litter, a man, wearing only a fur cloth about his middle. "What is it?" whispered Jack in awed accents. "They are fire-worshipers!" exclaimed Mark. "If they see us they'll kill us!" "They must be going to sacrifice that poor man on the altar," spoke Jack. "Come, let's see if we can't crawl out of the way." The head of the procession was now close to the altar, and had passed the adventurers, who were off to one side, in about the middle of the cavern. Up some ice steps the two giants in white went, bearing their victim. The poor fellow gave one loud shriek as he was brought nearer to the colored flames. "Oh! Oh! Oh!" screamed Dirola, sinking down on the floor of the cavern. CHAPTER XXIII A STRANGE SACRIFICE The natives who had made Professor Henderson, Andy, and Washington prisoners seemed at a loss for some little time as to which direction to take. They talked among themselves, while the prisoners were much alarmed, for if the Esquimaux were lost, and without food, it would mean the death of all.