As Mark gazed down into the depths, which seemed fathomless, and which were as black as night, he saw his friend clinging to a rocky projection on the side of the extinct volcano. Jack had managed to grasp a part of the rough surface as he slid down it after his reckless jump. He looked up and saw Mark. "Oh, Mark, can't you save me?" he gasped. "Call Professor Henderson!" "I'll get you up, don't worry!" called Mark, as confidently as he could. "Hold tight, Jack. What has become of your life-torch?" "I have it here by me. I didn't drop it, and it's on a piece of the rock near my head. Otherwise I couldn't breathe. Oh, this place is fearfully deep. I guess it hasn't any bottom." "Now, keep still, and don't think about that. Save your strength, hold fast, and I'll get you up." But, having said that much, Mark was not so sure how next to proceed. It was going to be no easy task to haul up Jack, and that without ropes or other apparatus. Another matter that added to the danger was the necessity of keeping the life-torch close to one's face in order to prevent death by the poisonous gases. Mark's first impulse was to hasten back and call the two professors, but he looked over the desolate landscape, and could not see them, and he feared that if he went away Jack might slip and fall into the unknown depths of the crater. "I've got to get him out alone," decided Mark. "But how can I do it?" He crawled cautiously nearer to the edge of the extinct volcano and looked down. A few loose stones, dislodged by his weight, rattled down the sides. "Look out!" cried Jack quickly, "or you'll fall, too!" "I'll be careful," answered Mark, and then he drew away out of danger, with a queer feeling about his heart, which was beating furiously. Mark had hoped to be able to make his way down the side of the crater to where his chum was and help him up. But a look at the steep sides and the uncertain footing afforded by the loose rocks of lava-like formation showed that this could not be done. "I've got to think of a different scheme," decided Mark, and, spurred on by the necessity of acting quickly if he was to save Jack, he fairly forced his brain to work. For he saw by the strained look on his chum's face that Jack could not hold out much longer. "I have it!" cried Mark at length. "My fur coat! I can cut it into strips of hide and make a rope. Then I can lower it down to Jack and haul him up." He did not think, for the moment, of the cold he would feel when he stripped off the fur garment, and when it did come to him in a flash he never hesitated. "After all, I've often been out without an overcoat on cold days," he said to himself. "I guess I can stand it for a while, and when Jack is up I can run back to the projectile and keep warm that way."