His heart and his senses failed him, as he struggled like a dying man to draw breath from the suffocating air. The precipice and the monster seemed to pitch and reel beneath him, the vapors swayed vertiginously, and he thought that he was plunging with his weird steed into the unfathomably shrouded gulf.

Then, from the burning mist, the hooded forms of white and shining devils appeared to rise up and seize him, as if to receive him into their unknown hell. He saw their strange, unhuman faces; he felt the touch of their fingers, with a queer and preternatural coolness, on his seared flesh; and then all was darkness… .

II

Howard awoke under circumstances that were novel and inexplicable. Instantly, with great clearness, he remembered all that had occurred prior to his final lapse, but could find no clue to his present situation.

He was lying on his back in a green radiance—a soft and soothing light that reminded him of the verdant grass and emerald seawater of the far-off Earth. The light was all about him, it seemed to flow beneath and above him, laving his body with cool ripples that left a sense of supreme well-being.

He saw that he was quite naked; and he had the feeling of immense buoyancy, as if he had been rendered weightless. Wondering, he saw that his skin was entirely free of burns, and realized that he felt no pain, no ill-effects of any kind, such as would have seemed inevitable after his dread ordeal in the Mercutian desert.

For awhile, he did not associate the green luminosity with any idea of spatial limitation; for he seemed to be floating in a vast abyss. Then, suddenly, he perceived his error. Putting out his hands, he touched on either side the wall of a narrow vault, and saw that its roof was only a few feet above him. The floor lay at an equal distance beneath; and he himself, without visible support, was reclining in mid-air. The green light, streaming mysteriously from all the sides of the vault, had given him the illusion of unbounded space.

Abruptly, at his feet, the end of the vault seemed to disappear in a white glory like pure sunlight. Long, sinuous, six-fingered hands reached out from the glow, grasped him about the ankles, and drew him gently from the green-lit space in which he floated. Weight seemed to return to him as his limbs and body entered the dazzling whiteness; and a moment later, he found himself standing erect in a large chamber, lined with some sort of pale, shimmering metal. Beside him, a strange, unearthly being was closing the panel-like door through which he had been drawn from the emerald-litten vault; and beyond this being, there were two others of the same type, one of whom was holding Howard’s garments in his arms.

In growing astonishment, Howard gazed at these incredible entities. Each of them was about the height of a tall man, and the physical conformation was vaguely similar to that of mankind, but was marked by an almost god-like beauty and grace of contour, such as could hardly have been found in the most perfect of antique marbles.

Nostrils, ears, lips, hands, and all other features and members, were carven with well-nigh fantastic delicacy; and the skin of these beings, none of whom wore any sort of raiment, was white and translucent, and seemed to shine with an internal radiance. In place of hair, the full, intellectual heads were crowned with a mass of heavy flesh-like filaments, hued with changing iridescence, and tossing and curling with a weird, restless life, like the serpent locks of Medusa. The feet were like those of men, except for long, horny spurs that protruded from the heels.

The three entities returned the earth-man’s gaze with unreadable eyes, brilliant as diamonds and cold as far-off stars. Then, to complete his amazement, the being who had just closed the door of the vault began to address him in high, flute-sweet tones, which baffled his ears at first, but after a little, became recognizable as flawless English.

“We trust,” said the being, “that you have recovered wholly from your late experience. It was fortunate that we were watching you through our televisors when you were seized by the savages and were bound to the back of the groko—that creature known to you as the ‘heat-lizard.’ These beasts are often tamed by the savages, who, being ignorant of the use of artificial heat, make a strange use of the groko’s proclivities for ranging the terrible sunward deserts. Captives caught from rival tribes—and sometimes even their own kin—are tied to the monsters, who carry them through oven-like temperatures till the victims are thoroughly roasted—or, as you would say, done to a turn. Then the grokos return to their masters—who proceed to feast on cooked meat.

“Luckily we were able to rescue you in time; for the groko, in its wanderings, approached one of our cavern-exits in the great desert. Your body was covered with enormous burns when we found you; and you would assuredly have died from the effects, if we had not exposed you to the healing ray in the green vault. This ray, like many others, is unknown to your scientists; and it has, among other things, the peculiar power of nullifying gravity. Hence your sensation of weightlessness under its influence.”

“Where am I? And who are you?” cried Howard.

“You are in the interior of Mercury,” said the being. “I am Agvur, a savant, and a high noble of the ruling race of this world.” He went on in a tone of half-disdainful explanation, as if lecturing to a child: “We call ourselves the Oumnis; and we are an old people, wise and erudite in all the secrets of nature. To protect ourselves from the intense radiations of the sun, which of course are more powerful on Mercury than on the further planets, we dwell in caverns lined with a metallic substance of our own composition. This substance, even in thin sheets, excludes all the harmful rays, some of which can pierce all other forms of matter to any depth. When we emerge to the outer world, we wear suits of this metal, whose name in our language is mouffa.

“Being thus insulated at all times, we are practically immortal, as well as exempt from disease; for all death and decay, in the course of nature, are caused by certain solar rays whose frequency is beyond detection of your instruments. The metal does not exclude the radiations that are beneficial and necessary to life; and by means of an apparatus similar in its principle to radio, our underworld is illumined with transmitted sunlight.”

Howard began to express his thanks to Agvur. His brain was giddy with wonder, and his thoughts whirled in a maze of astounding speculations.

Agvur, with a swift and graceful gesture, seemed to wave aside his expression of gratitude. The being who bore Howard’s garments came forward, and helped him, in a deft, valet-like fashion, to put them on.

Howard wanted to ask a hundred questions; for the very existence of intelligent, highly evolved beings such as the Oumnis on Mercury had been unsuspected by earth-scientists. Above all, he was curious regarding the mastery of human language displayed by Agvur. His question, as if divined by a sort of telepathy, was forestalled by the Mercutian.

“We are possessed of many delicate instruments,” said Agvur, “which enable us to see and hear—and even to pick up other sense-impressions—at immense distances. We have long studied the nearer planets, Venus, Earth and Mars, and have often amused ourselves by listening to human conversations. Our brain-development, which is vastly superior to yours, has made it a simple matter for us to learn your speech; and of course the science, history and sociology of your world is an open book to us. We watched the approach of your ether-ship from space; and all the movements of your party since landing have been observed by us.”

“How far am I from the rocket-ship?” asked Howard. “I trust you can help me to get back.”