Barber raised himself with a great effort and looked up. "No use," he said. "My heart--too much----" He fell forward again and that time he was very still, his desperate panting no more. * * * * * It seemed to Humbolt that it was half a lifetime later that he finally reached the spring and the cold, clear water. He drank, the most ecstatic pleasure he had ever experienced in his life. Then the pleasure drained away as he seemed to see Dan Barber trying to smile and seemed to hear him say, "It would be hell--to have to die--so thirsty like this." He rested for two days before he was in condition to continue on his way. He reached the plateau and saw that the woods goats had been migrating south for some time. On the second morning he climbed up a gentle roll in the plain and met three unicorns face to face. They charged at once, squealing with anticipation. Had he been equipped with an ordinary bow he would have been killed within seconds. But the automatic crossbow poured a rain of arrows into the faces of the unicorns that caused them to swing aside in pain and enraged astonishment. The moment they had swung enough to expose the area just behind their heads the arrows became fatal. One unicorn escaped, three arrows bristling in its face. It watched him from a distance for a little while, squealing and shaking its head in baffled fury. Then it turned and disappeared over a swell in the plain, running like a deer. He resumed his southward march, hurrying faster than before. The unicorn had headed north and that could be for but one purpose: to bring enough reinforcements to finish the job. * * * * * He reached the caves at night. No one was up but George Ord, working late in his combination workshop-laboratory. George looked up at the sound of his entrance and saw that he was alone. "So Dan didn't make it?" he asked. "The chasm got him," he answered. And then, wearily, "The chasm--we found the damned thing." "The red stratum----" "It was only iron stains." "I made a little pilot smelter while you were gone," George said. "I was hoping the red stratum would be ore. The other prospecting parties--none of them found anything." "We'll try again next spring," he said. "We'll find it somewhere, no matter how long it takes." "Our time may not be so long. The observations show the sun to be farther south than ever." "Then we'll make double use of the time we do have. We'll cut the hunting parties to the limit and send out more prospecting parties. We're going to have a ship to meet the Gerns again." "Sometimes," George said, his black eyes studying him thoughtfully, "I think that's all you live for, Bill: for the day when you can kill Gerns." George said it as a statement of a fact, without censure, but Humbolt could not keep an edge of harshness out of his voice as he answered: "For as long as I'm leader that's all we're all going to live for."