Aispha followed them on the slope; but the other people of Ciis, as had been stipulated by Furnham, paused at the juncture of their streets and buildings with the infra-violet substances of Earth.

After they had gone perhaps fifty yards on the gentle acclivity, Furnham came to a pause and waited for Aispha, holding out the Dōir at arm’s length. Somehow, he had a feeling that it was unwise to return the mystic egg; but he would keep his promise, since the people of Ciis had kept their part of the bargain so far.

Aispha took the Dōir from Furnham’s hands; but his thoughts, whatever they were, remained carefully shrouded. There was a sense of something ominous and sinister about him as he turned and went back down the slope with the fiery egg shining through his body like a great watchful eye. The beams of light were beginning to emanate from its center once more.

The two men, looking back ever and anon, resumed their journey. Ciis glimmered below them like the city of a mirage in the moonlit hollow. They saw the ultra-violet people crowding to await Aispha at the end of their streets.

Then, as Aispha neared his fellows, two rays of cold, writhing fire leaped forth from the base of a tower that glittered like glass at the city’s verge. Clinging to the ground, the rays ran up the slope with the undulant motion of pythons, following Langley and Furnham at a speed that would soon overtake them.

“They’re double-crossing us!” warned Furnham. He caught the Winchester from Langley, dropped to his knees and aimed carefully, drawing a bead on the luminous orb of the Dōir through the spectral form of Aispha, who had now reached the city and was about to enter the waiting throng.

“Run!” he called to Langley. “I’ll make them pay for their treachery; and perhaps you can get away in the meanwhile.”

He pulled the trigger, missing Aispha but dropping at least two of the Tiisins who stood near the Dōir. Again, steadily, he drew bead, while the rays from the tower serpentined onward, pale, chill and deadly-looking, till they were almost at his feet. Even as he aimed, Aispha took refuge in the foremost ranks of the crowd, through whose filmy bodies the Dōir still glowed.

This time, the high-powered bullet found its mark, though it must have passed through more than one of the ultra-violet beings before reaching Aispha and the mystic orb.

Furnham had hardly known what the result would be; but he had felt sure that some sort of catastrophe would ensue the destruction of the Dōir. What really happened was incalculable and almost beyond description.

Before the Dōir could fall from the hands of its stricken bearer, it seemed to expand in a rushing wheel of intense light, revolving as it grew and blotting out the forms of the ultra-violet people in the foreground. With awful velocity, the wheel struck the nearer buildings, which appeared to soar and vanish like towers of fading mirage. There was no audible explosion—no sound of any kind—only that silent, ever-spinning, ever-widening disk of light that threatened to involve by swift degrees the whole extent of Ciis.

Gazing spell-bound, Furnham had almost forgotten the serpentine rays. Too late, he saw that one of them was upon him. He leapt back, but the thing caught him, coiling about his limbs and body like an anaconda. There was a sensation of icy cold, of horrible constriction; and then, helpless, he found that the strange beam of force was dragging him back down the slope toward Ciis, while its fellow went on in pursuit of the fleeing Langley.

In the meanwhile, the spreading disk of fire had reached the tower from which the rays emanated. Suddenly Furnham was free—the serpentine beams had both vanished. He stood rooted to the spot in speechless awe; and Langley, returning to his aid, also paused, watching the mighty circle of light that seemed to fill the entire basin at their feet with a soundless vortex of destruction.

“My God!” cried Furnham, after a brief interval. “Look what’s happening to the slope.”

As if the force of the uncanny explosion were now extending beyond Ciis, boulders and masses of earth began to rise in air before the white, glowing maelstrom, and sailed in slow, silent levitation toward the men.

Furnham and Langley started to run, stumbling up the slope, and were overtaken by something that lifted them softly, buoyantly, irresistibly, with a strange feeling of utter weightlessness, and bore them like wind-wafted leaves or feathers through the air. They saw the bouldered crest of the acclivity flowing far beneath them; and then they were floating, floating, ever higher in the moonlight, above leagues of dim desert. A faintness came upon them both—a vague nausea—an illimitable vertigo—and slowly, somewhere in that incredible flight, they lapsed into unconsciousness.

The moon had fallen low, and its rays were almost horizontal in Furnham’s eyes when he awoke. An utter confusion possessed him at first; and his circumstances were more than bewildering. He was lying on a sandy slope, among scattered shrubs, meager and stunted; and Langley was lying not far away. Raising himself a little, he saw the white and reed-fringed surface of a river—which could be none other than the Tarim—at the slope’s bottom. Half- incredulous, doubting his own senses, he realized that the force of the weird explosion had carried Langley and himself many miles and had deposited them, apparently unhurt, beside the goal of their desert wanderings!

Furnham rose to his feet, feeling a queer lightness and unsteadiness. He took a tentative step—and landed four or five feet away. It was as if he had lost half his normal weight. Moving with great care he went over to Langley, who had now started to sit up. He was reassured to find that his eye-sight was becoming normal again; for he perceived merely a faint glowing in the objects about him. The sand and boulders were comfortably solid; and his own hands were no longer translucent.

“Gosh!” he said to Langley, “That was some explosion. The force that was liberated by the shattering of the Dōir—must have done something to the gravity of all surrounding objects. I guess the city of Ciis and its people have gone back into outer space; and even the infra-violet substances about the city must have been more or less degravitated. But I guess the effect is wearing off, as far as you and I are concerned—otherwise we’d be travelling still.”

Langley got up and tried to walk, with the same disconcerting result that had characterized Furnham’s attempt. He mastered his limbs and his equilibrium after a few experiments.

“I still feel like a sort of dirigible,” he commented. “Say, I think we’d better leave this out of our report to the museum. A city, a people, all invisible, in the heart of the Lob-nor—that would be too much for scientific credibility.”

“I agree with you,” said Furnham—“the whole business would be too fantastic, outside of a super-scientific story. In fact,” he added a little maliciously, “it’s even more incredible than the existence of the ruins of Kobar.”

THE IMMORTALS OF MERCURY

I

Cliff Howard’s first sensation, as he came back to consciousness, was one of well-nigh insufferable heat. It seemed to beat upon him from all sides in a furnace-like blast and to lie upon his face, limbs and body with the heaviness of molten metal. Then, before he had opened his eyes, he became aware of the furious light that smote upon his lids, turning them to a flame-red curtain. His eyeballs ached with the muffled radiation; every nerve of his being cringed from the pouring sea of incalescence; and there was a dull throbbing in his scalp, which might have been either headache induced by the heat, or the pain of a somewhat recent blow.

He recalled, very dimly, that there had been an expedition—somewhere—in which he had taken part; but his efforts to remember the details were momentarily distracted by new and inexplicable sensations. He felt now that he was moving swiftly, borne on something that pitched and bounded against a high wind that seared his face like the breath of hell.