A RATHER pretty girl was seated across from George Cleland, on the other side of the aisle. They were in the rear compartment of the gigantic, four-motor Al Fokker passenger plane, just taking off from the Alhambra field at Los Angeles, for the three-hour flight to San Francisco — or rather, to meet as weird and astounding an adventure as ever befell human beings. George was returning to his office in San Francisco, and to his engineering work after a summer’s vacation.

He watched the girl with interest as the steward handed her the little package of absorbent cotton with which to stop her ears against the oppressive roar of the motors. Clearly it was her first long flight. Her smooth cheeks were flushed with excitement; her shining gray eyes looked up quickly to see what the other passengers were doing with the cotton.

Her eyes met George’s. She smiled at him a little, accepting him as a companion in the adventure of the flight. He grinned, instructing her to twist the soft cotton into cylinders, and fit them into her ears. She smiled her thanks. Already the great plane had rolled across the field with ever-increasing speed, powerful motors thundering, had left the ground to rise easily through the low, gray fog, into the brilliant sunlight of the August morning.

George liked the girl. She was pretty. Soft brown hair, glistening with ruddy lights, tastefully arranged. Bright face flushed with excitement. Gray eyes shining.

She wore a dark green traveling suit, neat and trim. The body beneath it seemed to be neat and trim, too; athletic and well-developed. She looked like a co-ed. He remembered that the University at Berkeley would open in a few days, and supposed that she was flying up to attend it.

Two other men were sitting in that rear compartment with them—the great plane did not have a full load and four of the seats were empty. Facing George was a slender, meager, little, man, whose black suit was polished with wear. He wore enormously thick-lensed glasses, and his face was narrow, pinched, bird-like, so that he gave George’s imaginative mind the suggestion of a grotesque, goggle-eyed monster.

Presently he leaned forward, however, with the Map of the route that the steward had handed him, introduced himself as Howard Cann, said that he owned a dry goods store in Oakland, and asked George to help him locate the observatory which, according to the map, should be in sight on Mt. Wilson. His voice sounded thin and bird-like, above the unceasing roar of the motors. George pointed out the silver domes and towers shimmering on the crest of the mountain, in the bright August sunlight.

Cann nodded his thanks, and bent over the map again.

The other man was sunk sullenly into a seat facing the girl. George did not like him. His clothes fitted his bull-like form loosely, grotesquely. His heavy-jowled face was black with a short stubble of beard. From beneath a disreputable cape, pulled low over his forehead, he was staring at the girl, rather to her discomfort.

THE world of our senses, we are coming to learn, is not actually the world that exists in reality. What the real world may be, we have no means of knowing. Even our laws of nature are the product of our sensual observations, and may be fraught with as many errors as our other conceptions of the universe.

Einstein has introduced into our scientific thinking an almost, limitless vista of new worlds. Since everything is relative and nothing absolutely real, conceptions of other dimensions existing side by side with our own take on more of a semblance of probability. Those other dimensions may not be expected to be like our own world, they may be strange beyond all imagination.

Mr. Williamson is admirably fitted to deal with such bizarre worlds. His fluent, picturesque style conjures up instant images of strange places, and in the present story he tells us of a world that the immortal Edgar Allan Poe might have created.

His ferret eyes were black, shifty. George noticed that he swept the compartment watchfully with them, at intervals, always resuming his annoying gaze at the girl. I wouldn’t like to meet him on a dark night, thought George.

THEY had been up a little less than an hour when the astounding catastrophe took place.

The little, spectacled man who said his name was Cann had persisted in his high-voiced questions. George had pointed out to him the San Fernando and Santa Clara valleys, and Tejon Pass, and Lebec. They were just coming across the last gray mountain range, over the southern tip of the great San Joaquin Valley.

The air had been smooth, though the ship seemed to rise and fall with a slow, almost regular motion. The girl had seemed to be enjoying her flight immensely, peering out of the windows with a lively interest. Once or twice, to George’s pleasure, she had leaned over to watch when he was pointing out something of interest on Cann’s map.

Once she had asked some little question. Her voice, above the mighty, overwhelming roar of the four great motors, had seemed clear and pleasant. George began to regret that the flight and their companionship must end in a few short hours when the great plane glided down to the Alameda airport, across the bay from San Francisco.

But the plane, and most of her passengers, never reached Alameda.

George happened to be peering out when it occurred, trying to locate for Cann the town of Maricopa, which lay a little to the left, and ahead of the plane.

The air before the ship was suddenly filled with a blinding purple light, as though a great shell had burst, releasing a vast volume of incandescent violet vapor. A moment before, the sky had been clear. The purple cloud appeared suddenly, as if from thin air.

Its diameter must have been many miles, extending from the ground into the cloudless sky above them. The great plane was plunging almost at the center of it, and far too close for the pilot to turn aside.

George thinks, however, that the ship was suddenly tilted up, at the last instant, as if the pilot had attempted to zoom above the purple cloud. But it was only a moment after the cloud appeared that they struck it; the tragedy was occasioned by chance, not by any want of skill — and no display of skill could have averted it.

But as they pierced through it, George saw the purple cloud contract swiftly. It became a great, smooth-surfaced sphere of violet-reds radiance. Then, somehow, it seemed to flatten, become thinner, until it was only a disk of red-blue light.

It became a circle of purple flame, a hundred yards and more in diameter —we can judge its size only from George Cleland’s guess based on that quick glimpse of the amazing thing. A disk of amethystine fire, hanging in the air, with the great plane plunging away from its center.

A long, dreadful instant went by, after George knew that they had crashed through it. He had time to wonder what it was, to wonder if it could be only some trouble with his eyes, then he realized that others could see it for Cann shrank back from the window and clutched at his arm.

Without a sound or a vibration, they had passed through the purple disk, into a flood of crimson light!

George was dazed.

One instant, the blue sky was above and the green-blue fields beneath. The next, they were flying at some crazy angle beneath a sky that was red, plunging toward the foot of a precipitous cliff of jet-black rock.

The cloud of purple had been like a gate to another world. They had flashed through it, into another plane. of existence that seemed to lie co-existent with ours, yet more distant than the Andromeda nebula. To the science of a few decades ago, such a thing would have been incredible. But Einstein’s relativity, with its four-dimensional continuum, with its destruction of the old conception of space as an absolute dimension brings it much nearer to understandable phenomena. And it is confidently trusted that the implications of the incident narrated here will result in a farther modification of the changing theories of relativity.

The plane was hurtling toward the base of a rugged, towering wall of grim black rock, which had suddenly appeared beyond the purple disk. A crash was inevitable. The pilot had time only to bank the ship, causing it to strike the ebon cliff obliquely instead of head on.

George was stunned by the crash.

His last recollection was of their plunging flight toward the sheer, soaring wall of black rock, of the attempting turn that had failed to save them, of the splintering crashes and the merciless bruising shock of the collision with the mountain.

The Land of the Scarlet Sky

MEMORY did not return at once, as he recovered. He found himself lying in the bottom of a dark, cramped place, with a soft human body beside him. A hoarse voice, evidently that of the bearded man, was muttering curses, while heavy feet, apparently belonging to the same individual, were carelessly trampling George’s legs.

Then George caught the acrid odors of burning paint and gasoline.

His memory returned. He knew that the plane had crashed into the black mountain wall, that it was wrecked and in flames. The soft body against his was that of the girl. And it was the big man who was trampling on the others.

George tried to struggle up, pressing a hand to his head to try to stop the dizzy pain, to clear the faintness from his vision and the ringing noises from his ears, to sweep the misty clouds of pain from his mind.

A suffocating breath of flame came from the forward part of the ship, where the blaze had evidently started.

The fuselage was on its side, George saw. The door was above them. And the big, bull-like man, walking upon their bodies as carelessly as if they were sacks of grain, was struggling to open the door.

Suddenly there was a sham snap, as if he had broken a lock with the strength of his great, heavy hands. A moment later the door was thrown back, revealing the sky above, crimson, dark and sullen, red as if deluged in blood.

For a moment the strange scarlet sky was in view. Then thick masses of black smoke, touched with flickering, lurid yellow flames, floated across it. George heard the increasing roar of the conflagration.

He tried to struggle to his feet, still rubbing his throbbing head.

“Thanks, Mister,” came the hoarse voice of the giant, mockingly.

The huge man placed one heavy foot on George’s shoulder, while he was still on his knees, sprang forward. He clambered through the door in the uppermost side of the side.

George was sent crashing to the bottom of the compartment again, under the force of the ruthless kick.

Choking black smoke, so hot that it seared his lungs, was filling the little space when it struggled up again. The roar and crackle of the flames was growing swiftly louder. A black and yellow canopy of smoke and flame was rolling above the door.

Still his head throbbed with dull pain; his thoughts were slow, confused; he reeled, his knees buckled uncertainly.

“Not much time, now,” he muttered. “Guess they are all gone, in the front part of the ship.”

He bent beside the girl, lifted her with an effort, fighting to control his shaking knees. She was conscious.

“What’s—matter?” she whispered in a slow, uncertain voice.

“Plane smashed,” he said. “Burning. We must get out! Able to help? Do your best, but we have time.”

“I’ll try,” she murmured through white, compressed lips.

He lifted her in his arms. She grasped the side of the door, he pushed her up. She scrambled through it. For a moment she darkened the opening. Then she was gone from sight. Smoke and fire were still rolling over the opening.

The forward part of the plane was al-already an inferno. White heat drove down the aisle. Blinding, blistering smoke swirled into the compartment. Gasping for breath, tears streaming from his eyes, perspiration running from his skin under the scorching heat, the engineer stood still a moment, to recover from the exhausting effort that had been required to lift the girl through the door.

A choking groan came from beside his feet.

He bent, wiping the tears from his smoke-blinded eyes, distinguished the limp little body of Cann, lying in a little heap in a corner of the compartment, sprawled over the back of a seat.

“Poor Cann can’t,” he muttered in grim horror, as he began the very serious task of lifting the inert body through the door above him.

IN ever denser volumes, the smoke was pouring into the compartment, blinding, suffocating. Tears were streaming from George’s eyes, so that he could hardly see the bright square of the door above. The hot smoke seemed to dry and scorch his throat and lungs. He coughed, strangled. Sweat was pouring from his body; the heat was almost intolerable.

And he was still dazed and groggy front the blow that had stunned him when the great plane crashed. His head throbbed with leaden pains; his ears rang queerly; his thoughts were slow, confused. But he did not hesitate in beginning the grim task of saving the little man who had questioned him so persistently in his thin, bird-like tones.

Fighting the heavy inertia that tugged at him, George lifted the limp body and thrust it up toward the door. It was a terrific task. Some malignant demon seemed to be pressing back against him. His aching muscles relaxed, despite the fiercest effort of his will, the unconscious man fell back into his arms.

George bent, sucked in a deep breath of the cooler air that hung in the bottom of compartment, and raised himself, thrusting the body of the little man up again. At last his arms straightened; the still body was outside, lying beside the door, atop the fuselage.

A blistering tongue of lurid yellow flame licked through the compartment, up through the open door. George gasped and strangled from the hot breath of it. He felt hair burned from his head, felt the bare skin of his face and hands scorched.

Reeling from exhaustion and the lingering effects of the blow he had received when they fell, he bent for another gasping inhalation of the still breathable air in the bottom of the compartment. Then he stood up, grasped the sides of the door, leaped, and struggled to draw himself through it.

Burning smoke swirled up about him. He strangled, tried to hold his breath. His muscles cracked. The effort seemed almost beyond him, in his weakened condition. And an infernal river of smoke and flame seemed pouring across above the door. He shrank back from it.

Then he saw arm’s inert hand, still hanging in the door—glimpsed it through streaming, smarting eyes. He had to get out, to save the little man.

With a fast fierce effort, he swung himself up, got his feet upon the edges of the door, straightened up in a blast of smoke and flame. In a moment he bad snatched up Cann again, and leaped, blindly, desperately, into space.

He came down on bare, hard rock. The smoke was still blinding, he could feel the beating radiation of heat from the inferno which he had just escaped, but he was out of its intolerable area.

Gasping in great breaths of the cooler air, he dragged Cann over the rock, to where the heat was bearable. He dropped his limp burden, still drawing fresh air into his tortured lungs, and wiped his smarting eyes.

An amazing world he saw, when he was able to open his painful eyes. Half of it was hidden by the dense clouds of smoke and the lurid curtains of yellow flame that leaped from the blazing wreck of the plane; but in the half that he saw was matter enough for wonder and amazement.

The sky was red, intensely crimson, dark and oppressive. Like a dome cut from a monster ruby, and lit with a dull, sinister light from beyond. It was unbroken by cloud or sun or star. A pall of scarlet gloom, sullen and terrible.

Beneath the lowering, crimson sky was a barren waste of black rock. It resembled obsidian, without the glassy luster of the volcanic glass. It was a dead, dull black, somber and unrelieved by any gleam. It did not even reflect the angry fire of the scarlet sky.

It seemed that they were at the bottom of a vast pit or abyss, for sheer black precipices, like that against the foot of which the plane had crashed, rose about them in a rugged wall, leaping up to inconceivable heights.

George estimates that the diameter of this crater or pit must have been ten or a dozen miles, and he thinks the cliffs that ringed it must have been fully five miles high. No elevations of this abruptness are found on the earth, though several are to be observed upon the moon. The walls of several lunar ring-craters rise vertically for several miles. This abyss appeared to be of similar formation.

The floor of the pit was a rugged, tortured wilderness of black rock, cracked and warred, pitted with innumerable chasms, thrown up in miniature peaks, twisted into grotesque fantasies of lifeless black stone. George saw no tree, no bird or insect—no living thing at all.

He had no time to wonder at it, then. He merely swept the weird horizon of scarlet sky and stupendous dull black cliff with a single glance, and turned back to the burning plane.

An Explanation

WHERE was the girl? She had been conscious when he helped her through the door. Had she been able to reach a safe distance from the flaming ship? He heard a faint cry, and found her lying on the ground, several yards from the burning ship. She had been able to slip from the upper side of the fuselage to the ground, to stagger away a few steps before she collapsed.

George carried her out of the smoke, and placed her beside the still inert body of Cann.

She was still conscious, but weak and dizzy, suffering from concussion.

“Where are we?” she whispered. “The sky looks red. And these black mountains —they are so high!”

“I don’t know,” George said. “We’ll think of that after a while. I was almost wondering if I wasn’t seeing things. But we have a patient here to look after.”

He bent over Cann’s limp body.

“Oh!” the girl cried suddenly, with pain in her voice. “You are all burnt! Your face, and your hands! You stayed to carry us out!”

“What else could I do?” George asked. “There was another man that didn’t stay,” the girl said. “He trampled all over us, and then climbed out and left us to burn.” “Wonder where the kindly fellow is?” George said. He looked about them, over the rugged, desolate wilderness of twisted black stone.

But George paused to wonder again at the eldrich landscape spread out before him. The barren, lifeless waste of burned and tortured black rock. The mighty cliffs that plunged up beyond it—higher than any earthly mountains, so high they seemed unreal. They were nightmare mountains; cruel, looming crags from some drugged dream. Their rugged faces swept up far toward the zenith, surrounding the horizon. George had an unpleasant sense of oppression, as if those lofty, ebon walls were crowding them, smothering them.

And above the black peaks the sky was crimson, red as clouds of blood-mist, red as a dome of ruby lit with dull, sinister lights. It was lowering, gloomy, oppressive as the bald, looming walls—it shone with a dark and sullen glare.

The red of blood. The red of horror. The red of death.

George Cleland was frightened by it —though he took care not to show the girl his fears. He dropped his gaze from the fearful wonder of the new world, and resumed his slow examination of Cann’s body.

The little man was still unconscious. His clothing had been scorched and torn. His thick glasses were lost, and he looked oddly different without them—small and weak, like a child, or perhaps a crippled bird. His right upper arm had been broken. George pushed up the sleeve to examine it. On the skin was the blue print of a man’s heel; the bull-like man who sat opposite the girl had stepped on it, breaking the bone.

George straightened the limb, and tried to set it. But he could find nothing satisfactory to use for splints. There seemed to be no tree or bush—or any living thing at all—in the wilderness of black rock, from which he could get a splint. But during his search he made a curious discovery.

The barren waste of dead black stone was scattered with huge green crystals. Clear and transparent, as if cut from monster emeralds.

In shape, they resembled snow-crystals, as seen through the microscope. Six-pointed stars, with a delicate, symmetrical fretwork, never the same in two crystals, between the points. But they were far huger than snow-crystals. Three feet from point to point. They were usually three or four inches thick. The first one that George discovered, lying in a deep crack in the black rock, not far from where the plane had crashed, weighed about twenty pounds. He is unable to make any suggestion as to the material of which it was composed, though it seems that it must have crystallized in the air, and fallen as a snowflake falls in our world.

While George was working over Cann, the girl told him something of herself.

“My name is Juanita Harvel,” she said “Dad has a fruit ranch near Los Angeles. I was going up to Berkeley, to the University. I was to graduate this year—but my prospects, right now, aren’t very good.” She smiled a little. Then soberly, “Where can we be?”

“Your guess is as good as anybody’s,” George told her.

“DO you think—” she asked, and paused oddly, “do you think that—we could be dead? The plane smashed. It may have killed us all.”

“Not a bit,” George cried. “For myself, I feel very much alive and real—especially where the skin was cooked so it’s coming off!” He grinned painfully.

“Oh, I’m so sorry for you!” Juanita cried.

“That’s all right,” George assured her. “It won’t make much difference, if I’m dead. And if I’m alive, I’ll get well. We can cook up some sort of theory to account for it all. I suppose you’ve heard about the so-called Fourth Dimension?”

“Yes,” I’ve heard about it,” she admitted. “But as for understanding it—”

“There’s been a lot of bunk written on the subject, but nobody seems to know much about it. Einstein’s theory of relativity, however, introduces a fourth dimension, which is not different in any way from the three other dimensions we know. He says that to an observer on a different planet, the fourth dimension, or part of it, might appear as a spatial dimension; and one of the dimensions that appears spatial to us, would be, for him, partly or wholly the fourth dimension.

“Of course, I may be putting an intepretation on his work that he would not approve. He devised the hypothesis of the four-dimensional continuum, or ‘space-time’ as it is more generally called, to account for known facts. He was not interested in other worlds that might lie beside our own, billions of light years distant in our space, but touching the earth in the fourth dimension.

“The plane, you know, flew into a circle of purple light that appeared suddenly ahead of us. It may have been a sort of a gate to this other world, through the fourth dimension. This planet may be so far distant in space from our own world that it is in another universe, yet touching it in the fourth dimension.”

“How could that be?” Jaunita asked in a puzzled tone.

“I don’t know whether I can explain it very clearly. But a favorite method in such discussions is to form an analogy in dimensions of a lower order. Suppose we were two-dimensional beings, with length and width, but no thickness. Suppose our world were on the surface of a sheet of paper. And suppose this planet were on the other side of the sheet, just opposite.

“Being two-dimensional beings, we could not conceive of the third dimension, which is the thickness of the paper. We could not know of the other world so near, nor could we reach it except by going around the edge of the sheet.

“But suppose somebody stuck a pinhole in the paper, through the two worlds on opposite sides. Then we might blunder through, into a new world outside of our knowledge, just as the plane flew through that purple cloud into this strange place. So we must have fallen through a hole in the fourth dimension!”

“And what can we do about it?” Juanita asked.

“I don’t know. My theory may be the bunk, anyhow. But there was evidently some phenomenon, either of natural or artificial cause, which swept the plane through the ‘continuum’ from our world, to this. It may happen again. We must watch. If we see it happen, we may be able to find the cause, and manipulate it to act in reverse, to take us home. A slim chance, but our best bet!”

It was not very long before the flames of the wrecked plane died away. Only a mass of bare, blackened metal was left, scattered with charred bones. When the wreckage was cool enough, George found some traps of metal in it which he used as splints on Cann’s broken arm.

The little man remained unconscious.

For a very long time they stayed there, near the wreck—they did not know how long. George had lost his watch, and Juanita’s had been broken. There were no days in this weird world, no sun. The somber, angry crimson of the sky did not change, no luminous object appeared within it.

They grew thirsty, for there was no water to be had. They felt the pains of hunger. They reeled with weariness, and dared not sleep. But the physical hardships, at first, were more endurable than the mental torture.

They were in a strange world, absolutely foreign. It seemed that chemical and, physical processes here did not always follow the same course as on their own earth. There was no sun—only the sullen gloom of the crimson sky. No living things except themselves to break the terrible monotony.

Blood-red Rain!

THEIR minds struggled for an explanation of it all. How had they come here ? Was there any chance for escape? What was the meaning of the red sky? of the huge green crystals that scattered the stony wilderness? Of the inconceivably colossal black mountains?

The air was neither cold nor hot, its temperature remained constant. Faint radiation of heat, as well as light, seemed to fall from the somber scarlet sky. George suggested that the higher atmosphere was filled with some radioactive gas.

Cann never recovered consciousness. Nor did he die of his hurts. He was murdered. It came about in this way.

They must have been in the fantastic world of the adventure for many hours, for both George and Juanita were suffering keenly from hunger and thirst. They were still watching beside Cann. During those long, lonely hours, they had talked a great deal. They felt drawn together by a powerful sympathy, as if they had long been friends.

Both of them were startled immeasurably by the bullet. They had been waiting there a very long time, anxious, alert, waiting. They had been fearful of unknown dangers, fearful of the weird life that this world might possess, fearful even of the dead, endless silence.

The bullet came whining angrily past them. It struck the sheer face of the black cliff behind them with an explosive plop, and showered them with fine fragments of broken rock.

George started uncontrollably. Juanita half screamed, clapped a hand to her lips, and apprehensively grasped the engineer’s arm.

“What is it?” she gasped.

“Sounded like a bullet,” he said, uneasily. “Suppose the inhabitants of this world have firearms?”

“Look!” she whispered suddenly, in a strained voice. “Something moving!”

She pointed out across the cragged wilderness of dull black rock. Following her slender arm, George glimpsed a dark object slowly rising into view behind a twisted black boulder.

A little wisp of bluish smoke floated up beside it. They heard a crashing report, as another bullet sang past them and thudded against the precipice behind them, scattering bits of shattered rock.

“A man!” Juainta cried.

George saw that it was. A human head, covered with unkept black hair and a thick stubble of black beard. A human body rising behind it, grimy, clothed in tattered garments. It was the huge, sullen individual companion of their voyage.

“Why, it’s an old friend!” George whispered. “The man who admired you so much in the plane!” He grinned grimly.

“What does he mean, shooting at us?” Juanita cried.

“Guess it won’t hurt to ask him,” George said. He raised his voice, and shouted at the man. His tones came oddly shrill and strange from his dry throat.

“What do you want?” he called.

The man did not reply. But he left the shelter of the black boulder and stalked cautiously toward them, a huge, terrible figure, a pistol ready in his hand—a heavy automatic.

“What’s the idea, shooting at us?” George shouted again, in a shrill, thirst-cracked voice.

“I’m dyin’ for a drink,” the huge man growled back. “No water in this damn place! I’m thirsty as hell! I’ve got to drink! Blood!” Again and again, as he ran toward them, he repeated the word in a voice that had become almost a scream. “Blood! Blood! Blood!”

“He’s crazy !” George muttered.

Cann still lay unconscious on the bare black rock. When the huge man, charging down upon them, was thirty yards away, he shot again—into the body of the unconscious man. George saw the body jerk with the bullet’s impact.

“Oh!” the girl cried out in horror. Then whispered, “Let’s run! We can’t do anything!”

George took her hand; they ran off along the foot of the Cyclopean wall of dull black stone. They were weak from thirst and hunger and weariness; their bodies seemed very heavy. And the black rock over which they fled was so cracked and twisted, pitted with yawning chasms and broken with peaks and boulders and hummocks, that real running was impossible. Many times they stumbled. They leaped, and crawled, and climbed—jumped bottomless cracks, crept across narrow ledges, clambered up cliffs and boulders.

THE huge maniac shouted at them to stop, but they paid no heed. He fired at them twice. The bullets screamed past, and ricocheted among the black summits before them.

“Down!” George cried.

He leaped into a deep traverse crack in the black rock, between two massive, twisted summits, helped Juanita down beside him. They were out of the big man’s sight. Swiftly , they stumbled on, down the narrow ravine.

Half an hour later, when they had covered perhaps five hundred yards, they came up to where they could see the lunatic again. The huge fellow was bent over what was left of inoffensive little Cann, tearing at his body like a hungry wolf.

Horrified, they stumbled on again. Long hours—tortured ages—crept by. On and on they drove themselves. A man and a woman lost in an alien world. Sick with fear. Tortured with thirst. Weak from hunger. Reeling from fatigue. Driven on by the horror of what they had seen—one human being rending another like a ravening beast. ’

They did -not travel many miles. For they were weak. And the wilderness of black rock was incredibly rugged, twisted into fantastic, sharp-edged masses, carved with wild, volcanic energies.

The Cyclopean cliffs still hemmed them in, an impassable barrier, inconceivably lofty. Grim precipices leaped sheer half way to the zenith, all about them. Those mighty black cliffs were terrible, oppressive, like the stone walls of some ancient prison.

The scarlet sky still gleamed above the jagged summits of the ebon cliffs, with a dark and sullen glare, changeless, monotonous. There was neither day nor night; no sun nor moon nor stars ever broke the monotony of grim, forbidding crimson twilight.

It was a long time after they had left the sight of the wreck, when the red rain fell. Memory of the hideous orgy of the maniac already seemed faint to George; it had become unreal, a fantastic horror so far past that it did not matter.

Huge red drops began abruptly to fall from the crimson sky.

But they were not water that could be drunk—the laws of nature, or at least the chemical composition of the atmosphere, seemed to have been different on that weird world.

The great drops, red as blood, were at least a foot in diameter. They came thudding down with terrific force, scattering the waste of black rock. They did not spatter. They remained lying about, in spheroids shaped like drops of mercury—but larger than footballs!

George and Juanita sought shelter in a cave, beneath a sloping ledge of dull black rock, while the weird rain was falling.

The ground was by no means covered with red globules. George estimates that no more than two or three fell on every hundred square yards.

“Must be some new chemical, with an enormously strong surface film,” George speculated. “Mercury forms round drops like that, or water dropped in fine dust. But these drops are huge, compared to those. Atmospheric conditions here must be quite different to what they are on earth. You remember those big green crystals we’ve been finding. They must be a sort of snow that falls here. Some chemical crystallizing in the air, and falling as snow falls on earth—”

“There’s one!” Juanita cried.

She pointed from under the sheltering ledge of dull black rock. A broad, rugged ravine lay before them, a deep, cruel scar that bore witness to the cataclysmic birth of this alien world. On its farther slope, fifty yards away, was a glitter of green, standing out against the dead black of the rock. A huge, six-sided emerald crystal, sparkling and brilliant, like a snow crystal tinted green and enormously magnified.

Another of the riddles of this strange world.

Hours went by. The enormous red drops widely scattered still thudded down from the sky. The wanderers could see several of the puzzling scarlet spheroids. Suddenly George noticed that those they watched were dwindling in size.

“Look!” he cried. “They’re going away. Evaporating, I suppose. Must be some red gas in the sky; which condenses and falls, as rain does on earth. And they evaporate, to form clouds again.”

It was not long after that an amazing phenomenon took place. A falling red drop happened to strike the green crystal that Juanita had pointed out. George chanced to be watching the green formation speculatively when it occurred he heard the crashing explosion, saw a vast cloud of luminous purple vapor rise, as if some violent chemical reaction had taken place between the scarlet spheroid and the emerald crystal.

The great burst of shining red-violet vapor rushed up as suddenly as the white smoke of a bursting shell. It formed an enormous cloud. The cloud of purple contracted swiftly. But then it seemed to form an immense disk, Which they viewed obliquely.

Nearing the End

A FEW seconds went by, as they watchin astounded wonder.

Then the purple disk contracted swiftly and vanished.

George broke their silence with an excited cry, which came queerly through his dry throat.

“The purple circle that came in front of the plane looked just like that!” he cried. “We have seen the gate to our world opened again—I am sure of it—”

“There’s a bird!” Juanita broke in. “See!”

She pointed to a little gray sparrow, flitting uncertainly from where the purple disk had vanished. It circled aimlessly, rose in a wild, bewildered flight, became a little brown speck against the sullen crimson sky and vanished … .

“Yes,” George said slowly. “The bird came through it. A sparrow from our own world! It blundered through just as the plane did. I wonder—” He fell into silent speculation.

“You wonder what, George?” Juanita asked.

“I must think, dear!”

He patted her hand. A little hand, thin from starvation, red with cuts and scratches gained in their long struggle through the, desert of wild black rocks.

Feeling a faint thrill of pleasure at the “dear”, she fell silent, and sat watching him with cool gray eyes brightened with a faint light of hope. A long time went by, while the engineer remained silent, immersed in thought. The red rain stopped. “There’s no way of telling whether it will work the other way. We are pretty likely, to kill ourselves in the experiment. But it’s better to take a pretty big risk than end 1 our days here, eh?”

“You mean—” Juanita cried tremulously. “You mean—there’s a chance to get back home?”

Her gray eyes were wide with excitement and sudden hope.

“A chance,” George said. “A bare chance. But better than staying here until we die for want of food and water.”

“What is it?” she cried.

“We can find one of the green crystals, of course, and dump it one one of the red drops. There ought to be another explosion—and another opening of the gate to our world. I don’t understand the formation of the purple disk, of course. But something that results from the explosive union of the red drop and the green crystal seems to break down the barrier between the two worlds—some form of radiation, perhaps.

“Are you willing to try it?”

He looked into her cool gray eyes.

“Of course, George!” She smiled at him. A little smile, wan and strained. It had meant an effort against the weakness of hunger and the torture of thirst. “I’ll do anything you want to try. But we must hurry. The red drops, you know, are going away!”

“That’s right!” George replied in the hoarse whisper that his voice had become. “I’d forgotten. We must try it right away. It must be a rare coincidence for the green crystals and the red drops to be on the ground at the same time.”

Weak and reeling, they rose, and tottered out from beneath the sheltering black ledge. Searching down the long ravine, they came upon a few of the scarlet spheroids. Already they were shrunken to the size of a man’s fist. They were evaporating swiftly; little streamers of pinkish vapor were rising up from them. One of them dwindled and vanished, even as they were watching it.

For half an hour, they could not find on of the green crystals.

Then Juanita’s keen eyes discovered on standing on edge in a narrow crack in the dull black rock. George bent beside the crack, lifted it out. A great, six-pointed star of glistening green, brilliant and transparent, the feathery structure between the points delicate and perfectly symmetrical.

It weighed no more than thirty pounds, but the engineer, weakened by long hardship, reeled beneath the burden of it.

“Now to find one of the red drops,” he muttered

They struggled on down the ravine, George staggering beneath the weight of a blazing thing that might have been cut from a monster emerald by some gargantuan jeweler, Juanita dragging herself along by his side.

Once they came upon one of the scarlet spheroids. But it was no larger than a baseball, when they first saw it. As they staggered up to it, it dwindled swiftly, seeming to hiss like a drop of water on a hot stove. It was gone.

A sound came suddenly from behind them. A hoarse shout, insane, incoherent.

George turned in alarm. He saw a man running after them, a huge man with a black, bearded face—and red blood on his hands. The man who had reached this alien world in the plane with them. The man who had fallen like a wolf on the body of little insignificant Cann.

AN automatic pistol was in his blood-stained hand. “Guess he’s finished Cann,” George whispered. “Looking for fresh blood.”

“Oh, it will be dreadful if he catches us,” Juanita whispered. “Let’s run!”

“I don’t feel exactly fit for a Marathon!” George muttered.

But they broke into a stumbling run.

The wild, blood-stained figure behind shouted, gesticulated. Then they shots. Bullets whined and screamed about them, crashing on the dull black walls of the canyon.

They ran on—or tried to run. It was a pitiful, staggering pace; they were almost weak to move. George, reeling under burden of the green crystal, was gasping for breath. His tongue, swollen and leathery, seemed to fill his mouth, choking him. Juanita dragged her feeble, abused body along, keeping back any word of complaint.

The man running behind them was far stronger; he had had food recently. Swiftly he gained upon them, pausing to fire wildly after them with the pistol whenever a straight section of the ravine put them in his sight for a few minutes.

Then they came to the end of the canyon. Rugged walls of dead black rock rose before them, sheer, impossible to climb. They stopped, looked at it. George dropped the green crystal. He looked at Juanita.

“Well, I guess this means good-by,” he managed to articulate, in a hoarse, grating whisper. “Hope he makes it merciful. Anyhow, being with you has made it a lot more pleasant.”

He took Juanita’s hand, looked into her cool gray eyes, and tried to grin.

For the first time in their terrible adventure, Juanita burst into tears. She fell weakly into the engineer’s arms, sobbing uncontrollably, clinging to him with her thin, bruised arms.

The huge, blood-stained man came into view again, a hundred yards away. He stopped, threw up his automatic, and began to shoot. Bullets rang against the cliff behind them, sent splinters of black rock flying.

Then George, holding Juanita’s sob-shaken body in his arms, looked over her shoulder and saw the thing lying in a little crevice in the ebon rock, almost at their feet. A red spheroid, nearly a foot in diameter, with pale pink vapors hissing up from about it.

Several of the huge, strange crimson drops must have run together in the crevice, forming a single larger drop which did not evaporate so rapidly.

“Buck up!” the engineer cried, pushing the girl to her feet. “We’ll try it yet. We’ll beat our friend out of his dinner!”

He picked up the huge, glistening green crystal that he had dropped, tossed it into the crevice, upon the spheroid of scarlet-red liquid.

An explosive out-rush of purple vapor hurled them bodily backward, against the canyon wall. They crouched there a few seconds, waiting. George had an arm around Juanita’s waist, half-supporting her.

Abruptly the red-violet vapor receded from about them. It became a straight wall of purple light, the surface of a great disk.

“Now!” George whispered.

Half carrying Juanita’s slight body, he ran forward, leaped into that wall of red-blue light.

*

The next thing the engineer knew, they were lying sprawled in soft green grass. Juanita had fallen across his body, he sat up with her in his arms. He gazed at the world about him, and shed tears of relief and joy. The sky was no longer a sullen, angry red—it was soft and warmly blue.

Cyclopean, nightmare mountains of dull black stone no longer hemmed them in—they were surrounded by the green fields of the San Joaquin Valley. On one side of them a herd of Jersey cows was grazing. Beyond them stood a pleasant-looking farm house. On the other side was a fence, and beyond the fence, an unpaved country road.

The sound of an automobile engine reached George’s ears—sounding strange after his ages of silent imprisonment in that other world.

A farm truck, loaded with cans of milk, was coming down the road.

“A milk wagon!” he whispered to Juanita. “Let’s stop it!”

She responded feebly and they struggled over to the fence.

The farmer stopped to investigate these poor, tattered, bruised humans, who clung weakly to the fence, crying for joy. A few minutes later he had given each a few sips of milk from one of the cans, and was taking them to the pleasant farmhouse on the hill, where they would find many things that, in their terrible stay in the other world, they had known only in delirious dreams.

“Where on earth have you been?” asked the country doctor, who had been called in, and who assured them they would soon be completely recovered.

“You’d never believe it!” was George’s answer.

What Is Your Science Knowledge?

Test Yourself By This Questionnaire

1.How has it been theoretically determined to build a typewriter to operate by vocal dictation. (Page 1373)

2.What effect have various colors on nervous reactions? (Page 1389)

3.What has Einstein’s relativity done to our conceptions of space? (Page 1401)

4.What is the meaning of the four dimensional continuum? (Page 1405)

5.Who discovered X-rays? Radium? Cosmic Rays? (Page 1410)

6.What is an indication of the power of cosmic rays? (Page • 1412)

7.What was the home of primordial man? From what source did man spring? (Page 1452)

8.What is a diplodocus? (Page 1455)

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