He had gathered a handful of little fragments, and, keeping count of his steps, had shifted a bit of rock to his left hand for every hundred paces. By this he knew they must have gone five or six miles when he reached the tunnel's high point. Many times it had widened. Here, too, was a cave more than a hundred feet across. From the farther side the tunnel continued, pitching sharply downward, but Rawson did not explore farther. "I can seal that off with a flame-thrower," he said. "I've seen how they use them." Then he took Loah's light and looked with every evidence of approval at the rocky walls and the roof that seemed heavy with dew. He had wondered about the air, but he found that it seeped through from that central shaft, although Loah told him that in some deeper passages the air was bad. Here, although it was moving gently, it seemed wet as if charged with moisture. Rawson, staring upward, felt a drop strike him in the face, dripping from the rocks above. "It's a gamble," he said, "just a gamble. But the stakes are worth while. And now, Loah-San, we will return." * * * * * He made crude work with the flame-throwers at first but finally he got the knack, and the mouth of the tunnel beyond the big room was sealed. Then, with the help of Loah and some few of the others, he brought in more and more weapons of the Reds. He was curious as to their construction, but his curiosity had to go unsatisfied. They were only cylinders, so far as he could see, cylinders a foot long and six inches through, of some metal with the dull lustre of aluminum. But they were sealed, and he dared not cut one open with another flame-thrower for fear of what might come forth. On the top of each cylinder a tube was connected that ended in a lava tip; but at the base of the tube, where it joined the cylinder, was a sliding sleeve that checked the flame to nothing when it was moved, or opened it to the full blast. He had a hundred of them in the room when at last he was through--one hundred fearful instruments of destruction. And still he told no one of his plans; he only told Gor what he wanted done later on. "It may not work," he had to admit to himself. "I'm just guessing at the thickness of the rock and the power of these machines. It's a gamble, nothing but a gamble." He arranged the flame-throwers in a circle along the outer wall. The tops of the cylinders were curved, but the bottoms were flat and they set solidly on the rock. But he tipped them backward and braced them firmly with fragments of stone until every crooked-neck tube was pointed upward and toward the center. Finally he was done. * * * * *