clutched tightly. Mortis rigor had set in, it seemed, on the instant of death. But something bright attracted his gaze. It was a wide-banded gold ring encircling a middle finger. It hung loosely around the digit.
With a grunt, the tone of which bore something akin to joy, he lifted the boney hand, pried the fingers open and slipped off the ring. Instantly he recognized it. It was the ring Dr. Marsden had bought for the cabin boy in Rio!
Why hadn't he thought of the cabin boy before? He had completely forgotten the presence of the youth on the Scienta! So the skeleton was not Patti's after all! It was that of young Stebbins, a boy scout, first class, whom Dr. Marsden had taken along on his expedition to Brazil! The boy had begged to go along. Dr. Marsden had yielded. But to what a ghastly end!
Bob Allen at that moment was both happy and sad. He was happy that the bones were not all that remained of Patti Marsden. And he was sad because of the unkindly twist of fate, that had snuffed out the life of the boy who was not more than seventeen, if that old. He knew at a glance that the other two skeletons were those of big men. They were too large for Patti's delicate frame.
He fondled the ring curiously. It was the same heavy, green-gold ring Dr. Marsden had bought for the boy at Rio de Janiero. He recalled the purchase clearly. With Dr. Marsden and Stebbins, he had gone the round of the Rio curio stores. The boy had seen the ring and had wished for money enough to buy it. It had been rather a big ring for so small a boy, yet Stebbins had wanted it badly. He had been struck by the weird design of the Chinese jade stone. And so Dr. Marsden had purchased it as a present for the youth in return for excellent services rendered aboard the yacht.
But why hadn't the Subterranean ray destroyed it? Or was the strip-ray powerful enough to melt soft gold? The jade stone was gone, melted to black crisp. He could see that. Certainly the jade was harder than gold. Yet the metal was as beautiful as the day it had come out of the shop!
Struck with a strange idea, Bob Allen stared at the ring. Was the gold, he asked himself, immune to the powerful radium rays? Or had the ring, by a twist of fate, merely escaped the same destruction as the youth's flesh? No! he told himself. In that event, the jade would also have escaped. There could be no other explanation for the ring. Gold was immune to the strip-ray! But was it immune to the most powerful of Subterranean rays—that which disintegrated human bodies and ore-dust, causing them to vanish in a puff? He wondered.
Suddenly he decided to test out his idea. If he destroyed the ring in the experiment, nothing was lost. If the ray failed to destroy it, did not cause it to vanish—then he had made a discovery of vital importance to his fellow-men on the Surface.
Trembling with excitement and eagerness, he crept far back from the abyss, halting at the mouth of the overgrown trail. Here he laid the ring on a flat, thick rock. Tensely he aimed his taas tube at the golden band. With a lightning-like touch of his thumb on the button, he released what Larkin had said was the Inner World's most deadly ray.
There was a hissing sputter as the blue flash stabbed out from the tube. The weapon recoiled slightly in his hand. But the flash was instantaneous, vanishing as quickly as it bad been discharged. He had only meant to touch the gold band lightly with the beam, realizing that a prolonged ray might forever bury it in the earth.
He saw a small cloud of almost invisible blue dust rise up from the suddenly vanished rock. Eagerly he laid the tube aside and looked for the remains of the ring. It had vanished. He gave a grunt of dismay, but ran his hands through the dust that remained.
In a moment his fingers touched the ring. Jubilantly he brushed it off. It seemed to have been untouched by the ray. Under a thin coating of blue dust, the gold glittered as brilliantly as ever. He clutched the relic of death—and life, fondly, beaming with the happy realization that gold and perhaps gold alone was immune to the terrible taas rays of the Subterraneans! He could have performed a dance of joy at that moment, for he had by chance discovered a means for protecting his people on the Surface from the deadliest of rays produced by the Inner World murderers, the Subterranean assassins!
CHAPTER VIII
LIEUTENANT Bob Allen showed no further interest in the three skeletons lying, stripped of their flesh, on the crater's rim. Neither of them had once held the soft, yielding flesh of Patti Marsden. To him now, as he sat near the trail, meditating silently over his chance discovery that gold was immune to the destructive rays of the Inner World, they were just bones. And he had grown more or less hardened to human skeletons since his arrival among the Subterraneans. He did, however, feel the pangs of pity and sorrow for his unfortunate companions who had met death on the rim. But they were beyond all earthly help now. Therefore, they must be forgotten in place of more important thoughts at hand.
Those thoughts were: How could he get a warning to the Surface that the cruel warriors of the Subterranean were at the final hour of their carefully laid plans to strike the death knell to all humanity? How could he warn his people that only gold was immune to the terrible rays of the Inner World? If he could get word through to them the Surface armies and navies might successfully defend themselves behind shields of gold! But was there any way of escape from this dreadful world of the living dead? And where was Patti Marsden? What had happened to her? Was she alive or dead? Had she been taken captive or had she somehow managed to escape back to the Scienta? Was she, like the three skeletons on the rim, beyond his—all earthly help?
He resolved with grim determination to continue his search for her, meanwhile to look for an avenue of escape and to rack his tired brains for a way of sending an urgent warning to the Surface. Wearily he picked up his taas tube and with the aid of the spinning propellers on his back, he arose to his feet. As he did so, he felt a strange sensation of being watched. Something like the prick of a pin at the base of his skull caused him to grow suddenly tense. He knew instantly what it was! He had been discovered by the Subterraneans and they were projecting their thoughts into his brain by means of their strange powers of mental telepathy.
Instinctively he tried to hide his taas tube close to his body, while his eyes searched the terrain before him for
