"But even this could not continue forever. They must stop that loss of air. The process they had developed for reformation of matter admitted of a new use. Creation! They were now able to make new elements, elements that had never existed in nature! They designed atoms as, long before, their fathers had designed molecules. At last their problem was solved. They made a new form of matter that was clearer than any crystal, and yet stronger and tougher than any metal known. Since it held out none of the sun's radiations, they could roof their worlds with it and keep their air within!

"This was a task that could not be done in a year, nor a decade, but all time stretched out unending before them. One by one the three planets became tremendous, roofed-in cities. Only their vast powers, their mighty machines made the task possible, but it was done."

The droning voice of Tordos Gar ceased. Taj Lamor, who had listened with a mixture of amusement and impatience to the recital of a history he knew as well as the aged, garrulous narrator, waited out of the inborn respect which every man held for the Elders. At length he exclaimed: "I see no point—"

"But you will when I finish—or, at least, I hope you will." Tordos Gar's words and tone were gently reproving. He continued quietly:

"Slowly the ages drifted on, each marked by greater and greater triumphs of science. But again and again there were wars. Some there were in which the population of a world was halved, and all space for a billion miles about was a vast cauldron of incandescent energy in which tremendous fleets of space ships swirled and fused like ingredients in some cosmic brew. Forces were loosed on the three planets that sent even their mighty masses reeling drunkenly out of their orbits, and space itself seemed to be torn by the awful play of energies.

"Always peace followed—a futile peace. A few brief centuries or a few millennia, and again war would flame. It would end, and life would continue.

"But slowly there crept into the struggle a new factor, a darkening cloud, a change that came so gradually that only the records of instruments, made during a period of thousands of years, could show it. Our sun had changed from bright red to a deep, sullen crimson, and ever less and less heat poured from it. It was waning!

"As the fires of life died down, the people of the three worlds joined in a conflict with the common menace, death from the creeping cold of space. There was no need for great haste; a sun dies slowly. Our ancestors laid their plans and carried them out. The fifteen worlds were encased in shells of crystal. Those that had no atmosphere were given one. Mighty heating plants were built—furnaces that burned matter, designed to warm a world! At last a state of stability had been reached, for never could conditions change—it seemed. All external heat and light came from far-off stars, the thousands of millions of suns that would never fail.

"Under stress of the Great Change one scarcely noticed, yet almost incredible, transformation had occurred. We had learned to live with each other. We had learned to think, and enjoy thinking. As a species we had passed from youth into maturity. Advancement did not stop; we went on steadily toward the goal of all knowledge. At first there was an underlying hope that we might some day, somehow, escape from these darkened, artificial worlds of ours, but with the passing centuries this grew very dim and at length was forgotten.

"Gradually as millennia passed, much ancient knowledge was also forgotten. It was not needed. The world was unchanging, there was no strife, and no need of strife. The fifteen worlds were warm, and pleasant, and safe. Without fully realizing it, we had entered a period of rest. And so the ages passed; and there were museums and libraries and laboratories; and the machines of our ancestors did all necessary work. So it was—until less than a generation ago. Our long lives were pleasant, and death, when it came, was a sleep. And then—"

"And then," Taj Lamor interrupted, a sharp edge of impatience in his tone, "some of us awakened from our stupor!"

The Elder sighed resignedly. "You cannot see—you cannot see. You would start that struggle all over again!" His voice continued in what Taj Lamor thought of as a senile drone, but the younger man paid scant attention. His eyes and thoughts were centered on that brilliant yellow star, the brightest object in the heavens. It was that star, noticeably brighter within a few centuries, that had awakened a few men from their mental slumbers.

They were throwbacks, men who had the divine gift of curiosity; and sparked by their will to know, they had gone to the museums and looked carefully at the ancient directions for the use of the telectroscope, the mighty electrically amplified vision machine, had gazed through it. They had seen a great sun that seemed to fill all the field of the apparatus with blazing fire. A sun to envy! Further observation had revealed that there circled about the sun a series of planets, five, definitely; two more, probably; and possibly two others.

Taj Lamor had been with that group, a young man then, scarcely more than forty, but they had found him a leader and they had followed him as he set about his investigation of the ancient books on astronomy.

How many, many hours had he studied those ancient works! How many times had he despaired of ever learning their truths, and gone out to the roof of the museum to stand in silent thought looking out across the awful void to the steady flame of the yellow star! Then quietly he had returned to his self-set task.

With him as teacher, others had learned, and before he was seventy there were many men who had become true scientists, astronomers. There was much of the ancient knowledge that these men could not understand, for the science of a million centuries is not to be learned in a few brief decades, but they mastered a vast amount of the forgotten lore.

They knew now that the young, live sun, out there in space, was speeding toward them, their combined velocities equalling more than 100 miles each second. And they knew that there were not seven, but nine planets circling about that sun. There were other facts they discovered; they found that the new sun was far larger than theirs had ever been; indeed, it was a sun well above average in size and brilliance. There were planets, a hot sun—a home! Could they get there?

When their ancestors had tried to solve the problem of escape they had concentrated their work on the problem of going at speeds greater than that of light. This should be an impossibility, but the fact that the ancients had tried it, seemed proof enough to their descendants that it was possible, at least in theory. In the distant past they had needed speeds exceeding that of light, for they must travel light years; but now this sun was coming toward them, and already was less than two hundred and fifty billion miles away!

They would pass that other star in about seventy years. That was scarcely more than a third of a man's lifetime. They could make the journey with conceivable speeds—but in that brief period they must prepare to move!

The swift agitation for action had met with terrific resistance. They were satisfied; why move?

But, while some men had devoted their time to arousing the people to help, others had begun doing work that had not been done for a long, long time. The laboratories were reopened, and workshops began humming again. They were making things that were new once more, not merely copying old designs.

Their search had been divided into sections, search for weapons with which to defend themselves in case they were attacked, and search for the basic principles underlying the operation of their space ships. They had machines which they could imitate, but they did not understand them. Success had been theirs on these quests. The third section had been less successful. They had also been searching for secrets of the apparatus their forefathers had used to swing the planets in their orbits, to move worlds about at will. They had wanted to be able to take not only their space ships, but their planets as well, when they went to settle on these other worlds and in this other solar system.

But the search for this secret had remained unrewarded. The secret of the spaceships they learned readily, and Taj Lamor had designed these mighty ships below there with that knowledge. Their search for weapons had been satisfied; they had found one weapon, one of the deadliest that their ancestors had ever invented. But the one secret in which they were most interested, the mighty force barrage that could swing a world in its flight through space, was lost. They could not find it.

They knew the principles of the driving apparatus of their ships, and it would seem but a matter of enlargement to drive a planet as a ship, but they knew this was impossible; the terrific forces needed would easily be produced by their apparatus, but there was no way to apply them to a world. If applied in any spot, the planet would be torn asunder by the incalculable strain. They must apply the force equally to the entire planet. Their problem was one of application of power. The rotation of the planet made it impossible to use a series of driving apparatus, even could these be anchored, but again the sheer immensity of the task made it impossible.

Taj Lamor gazed down again at the great ships in the plaza below. Their mighty bulks seemed to dwarf even the huge buildings about them. Yet these ships were his—for he had learned their secrets and designed them, and now he was to command them as they flew out across space in that flight to the distant star.

He turned briefly to the Elder, Tordos Gar. "Soon we leave," he said, a faint edge of triumph in his voice. "We will prove that our way is right."

The old man shook his head. "You will learn—" he began, but Taj Lamor did not want to hear.

He turned, passed through a doorway, and stepped into a little torpedo-shaped car that rested on the metal roof behind him. A moment later the little ship rose, and then slanted smoothly down over the edge of the roof, straight for the largest of the ships below. This was the flagship. Nearly a hundred feet greater was its diameter, and its mile and a quarter length of gleaming metal hull gave it nearly three hundred feet greater length than that of the ships of the line.

This expedition was an expedition of exploration. They were prepared to meet any conditions on those other worlds—no atmosphere, no water, no heat, or even an atmosphere of poisonous gases they could rectify, for their transmutation apparatus would permit them to change those gases, or modify them; they knew well how to supply heat, but they knew too, that that sun would warm some of its planets sufficiently for their purposes.

Taj Lamor sent his little machine darting through the great airlock in the side of the gigantic interstellar ship and lowered it gently to the floor. A man stepped forward, opened the door for the leader, saluting him briskly as he stepped out; then the car was run swiftly aside, to be placed with thousands of others like it. Each of these cars was to be used by a separate investigator when they reached those other worlds, and there were men aboard who would use them.

Taj Lamor made his way to a door in the side of a great metal tube that threaded the length of the huge ship. Opening the door he sat down in another little car that shot swiftly forward as the double door shut softly, with a low hiss of escaping air. For moments the car sped through the tube, then gently it slowed and came to rest opposite another door. Again came the hissing of gas as the twin doors opened, and Taj Lamor stepped out, now well up in the nose of the cruiser. As he stepped out of the car the outer and inner doors closed, and, ready now for other calls, the car remained at this station. On a ship so long, some means of communication faster than walking was essential. This little pneumatic railway was the solution.

As Taj Lamor stepped out of the tube, a half-dozen men, who had been talking among themselves, snapped quickly to attention. Following the plans of the long-gone armies of their ancestors, the men of the expedition had been trained to strict discipline; and Taj Lamor was their technical leader and the nominal Commander-in-Chief, although another man, Kornal Sorul, was their actual commander.

Taj Lamor proceeded at once to the Staff Cabin in the very nose of the great ship. Just above him there was another room, walled on all sides by that clear, glass-like material, the control cabin. Here the pilot sat, directing the motions of the mighty ship of space.

Taj Lamor pushed a small button on his desk and in a moment a gray disc before him glowed dimly, then flashed into life and full, natural color. As though looking through a glass porthole, Taj Lamor saw the interior of the Communications Room. The Communications Officer was gazing at a similar disc in which Taj Lamor's features appeared.

"Have they reported from Ohmur, Lorsand, and Throlus, yet, Morlus Tal?" asked the commander.

"They are reporting now, Taj Lamor, and we will be ready within two and one half minutes. The plans are as before; we are to proceed directly toward the Yellow Star, meeting at Point 71?"

"The plans are as before. Start when ready."

The disc faded, the colors died, and it was gray again. Taj Lamor pulled another small lever on the panel before him, and the disc changed, glowed, and was steady; and now he saw the preparations for departure, as from an eye on the top of the great ship. Men streamed swiftly in ordered columns all about and into the huge vessels. In an incredibly short time they were in, and the great doors closed behind them. Suddenly there came a low, dull hum through the disc, and the sound mounted quickly, till all the world seemed humming to that dull note. The warning!

Abruptly the city around him seemed to blaze in a riot of colored light! The mighty towering bulks of the huge metal buildings were polished and bright, and now, as the millions of lights, every color of the spectrum, flashed over all the city from small machines in the air, on the ground, in windows, their great metal walls glistening with a riot of flowing color. Then there was a trembling through all the frame of the mighty ship. In a moment it was gone, and the titanic mass of glistening metal rose smoothly, quickly to the great roof of their world above them. On an even keel it climbed straight up, then suddenly it leaped forward like some great bird of prey sighting its victim. The ground beneath sped swiftly away, and behind it there came a long line of ships, quickly finding their position in the formation. They were heading toward the giant airlock that would let them out into space. There was but one lock large enough to permit so huge a ship to pass out, and they must circle half their world to reach it.

On three other worlds there were other giant ships racing thus to meet beyond their solar system. There were fifty ships coming from each planet; two hundred mighty ships in all made up this Armada of Space, two hundred gargantuan interstellar cruisers.

One by one the giant ships passed through the airlock and out into space. Here they quickly reformed as they moved off together, each ship falling into its place in the mighty cone formation, with the flagship of Taj Lamor at the head. On they rushed through space, their speed ever mounting. Suddenly there seemed to leap out of nowhere another mass of shining machines that flew swiftly beside them. Like some strange, shining ghosts, these ships seemed to materialize instantly beside and behind their fleet. They fell in quickly in their allotted position behind the Flagship's squadron. One—two more fleets appeared thus suddenly in the dark, and together the ships were flashing on through space to their goal of glowing fire ahead!

Hour after hour, day after day the ships flashed on through the awful void, the utter silence relieved by the communications between themselves and the slowly weakening communications from the far-off home planets.

But as those signals from home grew steadily weaker, the sun before them grew steadily larger. At last the men began to feel the heat of those rays, to realize the energy that that mighty sea of flame poured forth into space, and steadily they watched it grow nearer.

Then came a day when they could make out clearly the dim bulk of a planet before them, and for long hours they slowed down the flying speed of the ships. They had mapped the system they were approaching; there were nine planets of varying sizes, some on the near and some on the far side of the sun. There were but three on the near side; one that seemed the outermost of the planets, about 35,000 miles in diameter, was directly in their path, while there were two more much nearer the sun, about 100,000,000 and 70,000,000 miles distant from it, each about seven to eight thousand miles in diameter, but they were on opposite sides of the sun. These more inviting and more accessible worlds were numbers two and three of the planetary system. It was decided to split the expedition into two parts; one part was to go to planet two, and the other to three. Taj Lamor was to lead his group of a hundred ships to the nearer planet at once.

In a very brief time the great ships slanted down over what seemed to be a mighty globe of water. They were well in the northern hemisphere, and they had come near the planet first over a vast stretch of rolling ocean. The men had looked in wonder at such vast quantities of the fluid. To them it was a precious liquid, that must be made artificially, and was to be conserved, yet here they saw such vast quantities of natural water as seemed impossible. Still, their ancient books had told of such things, and of other strange things, things that must have been wondrously beautiful, though they were so old now, these records, that they were regarded largely as myths.

Yet here were the strange proofs! They saw great masses of fleecy water vapor, huge billowy things that seemed solid, but were blown lightly in the wind. And natural air! The atmosphere extended for hundreds of miles off into space; and now, as they came closer to the surface of this world the air was dense, and the sky above them was a beautiful blue, not black, even where there were stars. The great sun, so brilliantly incandescent when seen from space, and now a glowing globe of reddish-yellow.

And as they came near land, they looked in wonder at mighty masses of rock and soil that threw their shaggy heads high above the surrounding terrain, huge masses that rose high, like waves in the water, till they towered in solemn grandeur miles into the air! What a sight for these men of a world so old that age long erosion had washed away the last traces of hills, and filled in all of the valleys!

In awe they looked down at the mighty rock masses, as they swung low over the mountains, gazing in wonder at the green masses of the strange vegetation; strange, indeed, for they for uncounted ages had grown only mushroom-like cellulose products, and these mainly for ornament, for all their food was artificially made in huge factories.

Then they came over a little mountain lake, a body of water scarcely large enough to berth one of their huge ships, but high in the clear air of the mountains, fed by the melting of eternal snows. It was a magnificent sapphire in a setting green as emerald, a sparkling lake of clear water, deep as the sea, high in a cleft in the mountains.

In wonder the men looked down at these strange sights. What a marvelous home!

Steadily the great machines proceeded, and at last the end of the giant mountain was reached, and they came to a great plain. But that plain was strangely marked off with squares, as regularly as though plotted with a draftsman's square. This world must be inhabited by intelligent beings!

Suddenly Taj Lamor saw strange specks off in the far horizon to the south, specks that seemed to grow in size with terrific velocity; these must be ships, the ships of these people, coming to defend their home. The strangely pallid face of Taj Lamor tightened into lines of grim resolution. This was a moment he had foreseen and had dreaded. Was he to withdraw and leave these people unmolested, or was he to stand and fight for this world, this wonderfully beautiful home, a home that his race could live in for millions of years to come? He had debated this question many times before in his mind, and he had decided. There would never, never be another chance for his people to gain a new home. They must fight.

Swiftly he gave his orders. If resistance came, if an attack were made, they were to fight back at once, with every weapon at their disposal.

The strangers' ships had grown swiftly larger to the eye, but still, though near now, they seemed too small to be dangerous. These giant interstellar cruisers were certainly invulnerable to ships so small; their mere size would give them protection! These ships were scarcely as long as the diameter of the smaller of the interstellar ships—a bare two hundred and fifty feet for the largest.

The interstellar cruisers halted in their course, and waited for the little ships to approach. They were fast, for they drew alongside quickly, and raced to the front of the flagship. There was one small one that was painted white, and on it there was a large white banner, flapping in the wind of its passage. The rest of the ships drew off as this came forward, and stopped, hanging motionless before the control room of the giant machine. There were men inside—three strange men, short and oddly pink-skinned—but they were gesturing now, motioning that the giant machine settle to the ground beneath. Taj Lamor was considering whether or not to thus parley with the strangers, when suddenly there leaped from the white craft a beam of clear white—a beam that was directed toward the ground, then swung up toward the great cruiser in a swift arc!

As one, a dozen swift beams of pale red flared out from the giant and bathed the pigmy craft. As they reached it, the white ray that had been sweeping up suddenly vanished, and for an instant the ship hung poised in the air; then it began to swing crazily, like the pendulum of a clock—swung completely over—and with a sickening lurch sped swiftly for the plain nearly five miles below. In moments there came a brief flare, then there remained only a little crater in the soft soil.

But the red beams had not stopped with the little ship; they had darted out to the other machines, trying to reach them before they could bring those strange white rays into play. The cruisers obviously must win, for they carried dozens of projectors, but they might be damaged, their flight delayed. They must defeat those strangers quickly. The rays of Taj Lamor's ship lashed out swiftly, but almost before they had started, all the other ships, a full hundred, were in action, and the flagship was darting swiftly up and away from the battle. Below, those pale red rays were taking a swift toll of the little ships, and nearly twenty of them rolled suddenly over, and dashed to destruction far below.

But now the little ships were in swift darting motion. Because of their small size, they were able to avoid the rays of the larger interstellar cruisers, and as their torpedo-shaped hulls flashed about with bewildering speed, they began to fight back. They had been taken utterly by surprise, but now they went into action with an abandon and swiftness that took the initiative away from the gigantic interstellar liners. They were in a dozen places at once, dodging and twisting, unharmed, out of the way of the deadly red beams, and were as hard to hit as so many dancing feathers suspended over an air jet.

And if the pilots were skillful in avoiding enemy rays, their ray men were as accurate in placing theirs. But then, with a target of such vast size, not so much skill was necessary.

These smaller vessels were the ships of Earth. The people of the dark star had entered the solar system quite unannounced, except that they had been seen in passing the orbit of Mars, for a ship had been out there in space, moving steadily out toward Neptune, and the great interstellar cruisers, flashing in across space, away from that frigid planet, had not seen the tiny wanderer. But he had seen those mighty hulks, and had sent his message of danger out on the ether, warning the men of Earth. They had relayed it to Venus, and the ships that had gone there had received an equally warm reception, and were even now finding their time fully occupied trying to beat off the Interplanetary Patrol.

The battle ended as swiftly as it began, for Taj Lamor, in his machine high above, saw that they were outclassed, and ordered them to withdraw at once. Scarcely ten minutes had elapsed, yet they had lost twenty-two of their giant ships.

The expedition that had gone to Venus reported a similarly active greeting. It was decided at once that they should proceed cautiously to the other planets, to determine which were inhabited and which were not, and to determine the chemical and physical conditions on each.

The ships formed again out in space, on the other side of the sun, however, and started at once in compact formation for Mercury.

Their observations were completed without further mishap, and they set out for their distant home, their number depleted by forty-one ships, for nineteen had fallen on Venus.



I

The Terrestrian and Venerian governments had met in conference, a grim, businesslike discussion with few wasted words. Obviously, this was to be a war of science, a war on a scale never before known on either world. Agreements were immediately drawn up between the two worlds for a concerted, cooperative effort. A fleet of new and vastly more powerful ships must be constructed—but first they must have a complete report on the huge invading craft that had fallen in western Canada, and on Venus, for they might conceivably make their secrets their own.

They called for the scientists whose work had made possible their successful resistance of the marauders: Arcot, Morey and Wade. They found them working in the Arcot Laboratories.

"Wade," called Arcot tensely as he snapped the switch of the televisophone, "bring Morey and meet me at the machine on the roof at once. That was a call from Washington. I'll explain as soon as you get there."

On the roof Arcot opened the hangar doors, and entered the five-passenger molecular motion ship inside. Its sleek, streamlined sides spoke of power and speed. This was a special research model, designed for their experiments, and carrying mechanisms not found in commercial crafts. Among these were automatic controls still in the laboratory stage, but permitting higher speed, for no human being could control the ship as accurately as these.

It took the trio a little less than a quarter of an hour to make the 5,000 mile trip from New York to the battlefield of Canada. As they sped through the air, Arcot told them what had transpired. The three were passed through the lines at once, and they settled to the ground beside one of the huge ships that lay half buried in the ground. The force of the impact had splashed the solid soil as a stone will splash soft mud, and around the ship there was a massive ridge of earth. Arcot looked at the titanic proportions of this ship from space, and turned to his friends:

"We can investigate that wreck on foot, but I think it'll be far more sensible to see what we can do with the car. This monster is certainly a mile or more long, and we'd spend more time in walking than in investigation. I suggest, we see if there isn't room for the car inside. This beats even those huge Kaxorian planes for size." Arcot paused, then grinned. "I sure would have liked to mix in the fight they must have had here—nice little things to play with, aren't they?"

"It would make a nice toy," agreed Wade as he looked at the rows of wicked-looking projectors along the sides of the metal hull, "and I wonder if there might not be some of the crew alive in there? If there are, the size of the ship would prevent their showing themselves very quickly, and since they can't move the ship, it seems to me that they'll let us know shortly that they're around. Probably, with the engines stopped, their main weapons are useless, but they would doubtless have some sort of guns. I'm highly in favor of using the car. We carry a molecular director ray, so if the way is blocked, we can make a new one."

Wade's attention was caught by a sudden flare of light a few miles across the plain. "Look over there—that ship is still flaming—reddish, but almost colorless. Looks like a gas flame, with a bit of calcium in it. Almost as if the air in the ship were combustible. If we should do any exploring in this baby, I suggest we use altitude suits—they can't do any harm in any case."

Three or four of the great wrecks, spread over a wide area, were burning now, hurling forth long tongues of colorless, intensely hot flame. Several of the ships had been only slightly damaged; one had been brought down by a beam that had torn free the entire tail of the ship, leaving the bow in good condition. Apparently this machine had not fallen far; perhaps the pilot had retained partial control of the ship, his power failing when he was only a comparatively short distance from Earth. This was rather well to one side of the plain, however, and they decided to investigate it later.

The ship nearest them had crashed nose first, the point being crushed and shattered. Arcot maneuvered his craft cautiously toward the great hole at the nose of the ship, and they entered the mighty vessel slowly, a powerful spotlight illuminating the interior. Tremendous girders, twisted and broken by the force of impact, thrust up about them. It soon became evident that there was little to fear from any living enemies, and they proceeded more rapidly. Certainly no creature could live after the shock that had broken these huge girders! Several times metal beams blocked their path, and they were forced to use the molecular director ray to bend them out of the way.

"Man," said Arcot as they stopped a moment to clear away a huge member that was bent across their path, "but those beams do look as if they were built permanently! I'd hate to ram into one of them! Look at that one—if that has anywhere near the strength of steel, just think of the force it took to bend it!"

At last they had penetrated to the long tube that led through the length of the ship, the communication tube. This admitted the small ship easily, and they moved swiftly along till they came to what they believed to be about the center of the invader. Here Arcot proposed that they step out and see what there was to be seen.

The others agreed, and they at once put on their altitude suits of heavy rubberized canvas, designed to be worn outside the ship when at high altitude, or even in space. They were supplied with oxygen tanks that would keep the wearer alive for about six hours. Unless the atmosphere remaining in the alien ship was excessively corrosive, they would be safe. After a brief discussion, they decided that all would go, for if they met opposition, there would be strength in numbers.

They met their first difficulty in opening the door leading out of the communication tube. It was an automatic door, and resisted their every effort—until finally they were forced to tear it out with a ray. It was impossible to move it in any other way. The door was in what was now the floor, since the ship seemed to have landed on one side rather than on its keel.

They let themselves through the narrow opening one at a time, and landed on the sloping wall of the corridor beyond.

"Lucky this wasn't a big room, or we'd have had a nice drop to the far wall!" commented Wade. The suits were equipped with a thin vibrating diaphragm that made speech easy, but Wade's voice came through with a queerly metallic ring.

Arcot agreed somewhat absently, his attention directed toward their surroundings. His hand light pierced the blackness, finally halting at a gaping opening, apparently the entrance to a corridor. As they examined it, they saw that it slanted steeply downward.

"It seems to be quite a drop," said Wade as he turned his light into it, "but the surface seems to be rather rough. I think we can do it. I notice that you brought a rope, Morey; I think it'll help. I'll go first, unless someone else wants the honor."

"You go first?" Arcot hesitated briefly. "But I don't know—if we're all going, I guess you had better, at that. It would take two ordinary men to lower a big bulk like you. On the other hand, if anybody is going to stay, you're delegated as elevator boy!

"Hold everything," continued Arcot. "I have an idea. I think none of us will need to hold the weight of the others with the rope. Wade, will you get three fairly good-sized pieces of metal, something we can tie a rope to? I think we can get down here without the help of anyone else. Morey, will you cut the rope in three equal pieces while I help Wade tear loose that girder?"

Arcot refused to reveal his idea till his preparations were complete, but worked quickly and efficiently. With the aid of Wade, he soon had three short members, and taking the rope that Morey had prepared, he tied lengths of cord to the pieces of metal, leaving twenty foot lengths hanging from each. Now he carefully tested his handiwork to make sure the knots would not slip.

"Now, let's see what we can do." Arcot put a small loop in one end of a cord, thrust his left wrist through this, and grasped the rope firmly with his hand. Then he drew his ray pistol, and adjusted it carefully for direction of action. The trigger gave him control over power. Finally he turned the ray on the block of metal at the other end of the rope. At once the metal pulled vigorously, drawing the rope taut, and as Arcot increased the power, he was dragged slowly across the floor.

"Ah—it works." He grinned broadly over his shoulder. "Come on, boys, hitch your wagon to a star, and we'll go on with the investigation. This is a new, double action parachute. It lets you down easy, and pulls you up easier! I think we can go where we want now." After a pause he added, "I don't have to tell you that too much power will be very bad!"

With Arcot's simple brake, they lowered themselves into the corridor below, descending one at a time, to avoid any contact with the ray, since the touch of the beam was fatal.

The scene that lay before them was one of colossal destruction. They had evidently stumbled upon the engine room. They could not hope to illuminate its vast expanse with their little hand lights, but they could gain some idea of its magnitude, and of its original layout. The floor, now tilted at a steep angle, was torn up in many places, showing great, massive beams, buckled and twisted like so many wires, while the heavy floor plates were crumpled like so much foil. Everywhere the room seemed covered with a film of white silvery metal; it was silver, they decided after a brief examination, spattered broadcast over the walls of the room.

Suddenly Morey pointed ceilingward with his light. "That's where the silver came from!" he exclaimed. A network of heavy bars ran across the roof, great bars of solid silver fully three feet thick. In one section gaped a ragged hole, suggesting the work of a disintegration ray, a hole that went into the metal roof above, one which had plainly been fused, as had the great silver bars.

Arcot looked in wonder at the heavy metal bars. "Lord—bus bars three feet thick! What engines they must have! Look at the way those were blown out! They were short circuited by the crash, just before the generator went out, and they were volatilized! Some juice!"

With the aid of their improvised elevators, the three men attempted to explore the tremendous chamber. They had scarcely begun, when Wade exclaimed:

"Bodies!"

They crowded around his gruesome find and caught their first glimpse of the invaders from space. Anatomical details could not be distinguished since the bodies had been caught under a rain of crushing beams, but they saw that they were not too different from both Terrestrians and Venerians—though their blood seemed strangely pallid, and their skin was of a ghastly whiteness. Evidently they had been assembled before an unfamiliar sort of instrument panel when catastrophe struck; Morey indicated the dials and keys.

"Nice to know what you're fighting," Arcot observed. "I've a hunch that we'll see some of these critters alive—but not in this ship!"

They turned away and resumed their examination of the shattered mechanisms.

A careful examination was impossible; they were wrecks, but Arcot did see that they seemed mainly to be giant electrical machines of standard types, though on a gargantuan scale. There were titanic masses of wrecked metal, iron and silver, for with these men silver seemed to replace copper, though nothing could replace iron and its magnetic uses.

"They are just electrical machines, I guess," said Arcot at last. "But what size! Have you seen anything really revolutionary, Wade?"

Wade frowned and answered. "There are just two things that bother me. Come here." As Arcot jumped over, nearly suspended by his ray pistol, Wade directed his light on a small machine that had fallen in between the cracks in the giant mass of broken generators. It was a little thing, apparently housed in a glass case. There was only one objection to that assumption. The base of a large generator lay on it, metal fully two feet thick, and that metal was cracked where it rested on the case, and the case, made of material an inch and a half thick, was not dented!

"Whewww—that's a nice kind of glass to have!" Morey commented. "I'd like to have a specimen for examination. Oh—I wonder—yes, it must be! There's a window in the side up there toward what was the bow that seemed to me to be the same stuff. It's buried about three feet in solid earth, so I imagine it must be."

The three made their way at once to where they had seen the window. The frame appeared to be steel, or some such alloy, and it was twisted and bent under the blow, for this was evidently the outer wall, and the impact of landing had flattened the rounded side. But that "glass" window was quite undisturbed! There was, as a further proof, a large granite boulder lying against it on the outside—or what had been a boulder, though it had been shattered by the impact.

"Say—that's some building material!" Arcot indicated the transparent sheet. "Just look at that granite rock—smashed into sand! Yet the window isn't even scratched! Look how the frame that held it is torn—just torn, not broken. I wonder if we can tear it loose altogether?" He stepped forward, raising his pistol. There was a thud as his metal bar crashed down when the ray was shut off. Then, as the others got out of the way, he stepped toward the window and directed his beam toward it. Gradually he increased the power, till suddenly there was a rending crash, and they saw only a leaping column of earth and sand and broken granite flying up through the hole in the steel shell. There was a sudden violent crash, then a moment later a second equally violent crash as the window, having flown up to the ceiling, came thumping back to the floor.

After the dust had settled they came forward, looking for the window. They found it, somewhat buried by the rubbish, lying off to one side. Arcot bent down to tilt it and sweep off the dirt; he grasped it with one hand, and pulled. The window remained where it was. He grasped it with both hands and pulled harder. The window remained where it was.

"Uh—say, lend a hand will you, Wade." Together the two men pulled, but without results. That window was about three feet by two feet by one inch, making the total volume about one-half a cubic foot, but it certainly was heavy. They could not begin to move it. An equal volume of lead would have weighed about four hundred pounds, but this was decidedly more than four hundred pounds. Indeed, the combined strength of the three men did not do more than rock it.

"Well—it certainly is no kind of matter we know of!" observed Morey. "Osmium, the heaviest known metal, has a density of twenty-two and a half, which would weigh about 730 pounds. I think we could lift that, so this is heavier than anything we know. At least that's proof of a new system. Between Venus and Earth we have found every element that occurs in the sun. These people must have come from another star!"

"Either that," returned Arcot, "or proof of an amazing degree of technological advancement. It's only a guess, of course—but I have an idea where this kind of matter exists in the solar system. I think you have already seen it—in the gaseous state. You remember, of course, that the Kaxorians had great reservoirs for storing light-energy in a bound state in their giant planes. They had bound light, light held by the gravitational attraction for itself, after condensing it in their apparatus, but they had what amounted to a gas—gaseous light. Now suppose that someone makes a light condenser even more powerful than the one the Kaxorians used, a condenser that forces the light so close to itself, increases its density, till the photons hold each other permanently, and the substance becomes solid. It will be matter, matter made of light—light matter—and let us call it a metal. You know that ordinary matter is electricity matter, and electricity matter metals conduct electricity readily. Now why shouldn't our 'light matter' metal conduct light? It would be a wonderful substance for windows."

"But now comes the question of moving it," Wade interposed. "We can't lift it, and we certainly want to examine it. That means we must take it to the laboratory. I believe we're about through here—the place is clearly quite permanently demolished. I think we had better return to the ship and start to that other machine we saw that didn't appear to be so badly damaged. But—how can we move this?"

"I think a ray may do the trick." Arcot drew his ray pistol, and stepped back a bit, holding the weapon so the ray would direct the plate straight up. Slowly he applied the power, and as he gradually increased it, the plate stirred, then moved into the air.

"It works! Now you can use your pistol, Morey, and direct it toward the corridor. I'll send it up, and let it fall outside, where we can pick it up later." Morey stepped forward, and while Arcot held it in the air with his ray, Morey propelled it slowly with his, till it was directly under the corridor leading upward. Then Arcot gave a sudden increase in power, and the plate moved swiftly upward, sailing out of sight. Arcot shut off his ray, and there came to their ears a sudden crash as the plate fell to the floor above.

The three men regained their ropes and "double action parachutes" as Arcot called them, and floated up to the next floor. Again they started the process of moving the plate. All went well till they came to the little car itself. They could not use the ray on the car, for fear of damaging the machinery. They had to use some purely mechanical method of hoisting it in.

Finally they solved the problem by using the molecular director ray to swing a heavy beam into the air, then one man pulled on the far end of it with a rope, and swung it till it was resting on the door of the ship on one end, and the other rested in a hole they had torn in the lining of the tube.

Now they maneuvered the heavy plate till it was resting on that beam; then they released the plate, and watched it slide down the incline, shooting through the open doorway of the car. In moments the job was done. The plate at last safely stowed, the three men climbed into the car, and prepared to leave.

The little machine glided swiftly down the tube through the mighty ship, finally coming out through the opening that had admitted them. They rose quickly into the air, and headed for the headquarters of the government ships.



II

A great number of scientists and military men were already gathered about the headquarters ship. As Arcot's party arrived, they learned that each of the wrecks was being assigned to one group. They further learned that because of their scientific importance, they were to go to the nearly perfect ship lying off to the west. Two Air Patrolmen were to accompany them.

"Lieutenant Wright and Lieutenant Greer will go with you," said the Colonel. "In the event of trouble from possible—though unlikely—survivors, they may be able to help. Is there anything further we can do?"

"These men are armed with the standard sidearms, aren't they?" Arcot asked. "I think we'll all be better off if I arm them with some of the new director-ray pistols. I have several in my boat. It will be all right, I suppose?"

"Certainly, Dr. Arcot. They are under your command."

The party, increased to five now, returned to the ship, where Arcot showed the men the details of the ray pistols, and how to use them. The control for direction of operation was rather intricate in these early models, and required considerable explanation. The theoretical range of even these small hand weapons was infinity in space, but in the atmosphere the energy was rather rapidly absorbed by ionization of the air, and the dispersion of the beam made it ineffective in space over a range of more than thirty-five miles.

Again entering the little molecular motion car, they went at once to the great hull of the fallen ship. They inspected it cautiously from overhead before going too close, for the dreadnought, obviously, had landed without the terrific concussion that the others had experienced, and there was a possibility that some of the crew had survived the crash. The entire stern of the huge vessel had been torn off, and evidently the ship was unable to rise, but there were lights glowing through the portholes on the side, indicating that power had not failed completely.

"I think we'd better treat that monster with respect," remarked Wade, looking down at the lighted windows. "They have power, and the hull is scarcely dented except where the stern was caught by a beam. It's lucky we had those ray projector ships! They've been in service only about four months, haven't they, Lieutenant?"

"Just about that, sir," the Air Patrolman replied. "They hadn't gotten the hand weapons out in sufficient quantities to be issued to us as yet."

Morey scowled at the invader. "I don't like this at all. I wonder why they didn't greet us with some of their beams," he said in worried tones. It did seem that there should be some of the rays in action now. They were less than a mile from the fallen giant, and moving rather slowly.

"I've been puzzled about that myself," commented Arcot, "and I've come to the conclusion that either the ray projectors are fed by a separate system of power distribution, which has been destroyed, or that the creatures from space are all dead."

They were to learn later, in their exploration of the ship, that the invaders' ray projectors were fed from a separate generator, which produced a special form of alternating current wave for them. This generator had been damaged beyond use.

The little machine was well toward the stern of the giant now, and they lowered it till it was on a level with the torn metal. It was plain that the ship had been subjected to some terrific tension. The great girders were stretched and broken, and the huge ribs were bent and twisted. The central tube, which ran the length of the ship, had been drawn down to about three quarters of its original diameter, making it necessary for them to use their ray to enter. In moments their speedster glided into the dark tunnel. The searchlight reaching ahead filled the metal tunnel with a myriad deceptive reflections. The tube was lighted up far ahead of them, and seemed empty. Cautiously they advanced, with Arcot at the controls.

"Wade—Morey—where will we stop first?" he asked. "The engines? They'll probably be of prime importance. We know their location. What do you say?"

"I agree," replied Wade, and Morey nodded his approval.

They ran their craft down the long tube till they reached the door they knew must be the engine room landing, and stepped out, each wearing an altitude suit. This ship had landed level, and progress would be much easier than in the other one. They waited a moment before opening the door into the engine room, for this led into a narrow corridor where only one could pass. Caution was definitely in order. The Air Patrolmen insisted on leading the way. They had been sent along for the express purpose of protecting the scientists, and it was their duty to lead. After a brief argument Arcot agreed.

The two officers stepped to the door, and standing off to one side, tore it open with a ray from their pistols. It fell with a clatter to the rounded metal floor of the tube, and lay there vibrating noisily, but no rays of death lanced out from beyond it. Cautiously they peered around the corner of the long corridor, then seeing nothing, entered. Wade came next, then Arcot, followed by Morey.

The corridor was approximately thirty feet long, opening into the great engine room. Already the men could hear the smooth hum of powerful machines, and could see the rounded backs of vast mechanisms. But there was no sign of life, human or otherwise. They halted finally at the threshold of the engine room.

"Well," Arcot said softly. "We haven't seen anyone so far, and I hope no one has seen us. The invaders may be behind one of those big engines, quite unaware of us. If they're there, and they see us, they'll be ready to fight. Now remember, those weapons you have will tear loose anything they hit, so take it easy. You know something about the power of those engines, so don't put them out of commission, and have them splash us all over the landscape.

"But look out for the crew, and get them if they try to get you!"

Cautiously but quickly they stepped out into the great room, forming a rough half circle, pistols ready for action. They walked forward stealthily, glancing about them—and simultaneously the enemies caught sight of each other. There were six of the invaders, each about seven feet tall, and surprisingly humanoid. They somewhat resembled Venerians, but they weren't Venerians, for their skin was a strange gray-white, suggesting raw dough. It seemed to Arcot that these strange, pale creatures were advancing at a slow walk, and that he stood still watching them as they slowly raised strange hand weapons. He seemed to notice every detail: their short, tight-fitting suits of some elastic material that didn't hamper their movements, and their strange flesh, which just seemed to escape being transparent. Their eyes were strangely large, and the black spot of the pupil in their white corneas created an unnatural effect.

Then abruptly their weapons came up—and Arcot responded with a sudden flick of his ray, as he flung himself to one side. Simultaneously his four companions let their beams fly toward the invaders. They glowed strangely red here, but they were still effective. The six beings were suddenly gone—but not before they had released their own beams. And they had taken toll. Lieutenant Wright lay motionless upon the floor.

The Terrestrians scarcely had a chance to notice this, for immediately there was a terrific rending crash, and clean daylight came pouring in through a wide opening in the wall of the ship. The five rays had not stopped on contact with the enemy, but had touched the wall behind them. An irregular opening now gaped in the smooth metal.

Suddenly there came a second jarring thud, a dull explosion; then a great sheet of flame filled the hole—a wall of ruddy flame swept rapidly in. Arcot swung up his ray pistol, pointing it at the mass of flaming gas. A mighty column of air came through the narrow corridor from the tube, rushing toward the outside, and taking the flame with it. A roaring mass of gas hovered outside of the ship.

"Lieutenant," said Arcot, swiftly, "turn your ray on that hole, and keep it there, blowing that flame outside with it. You'll find you can't put the fire out, but if you keep it outside the ship, I believe we'll be reasonably safe." The Patrolman obeyed instantly, relieving Arcot.

Wade and Morey were already bending over the fallen man.

"I'm afraid there's nothing we can do for him," the latter said grimly, "and every moment here is dangerous. Let's continue our investigation and carry him back to the ship when we leave." Arcot nodded silently.

Solemnly they turned away from the motionless figure on the floor and set out on their investigation.

"Arcot," began Morey after a moment, "why is that gas burning like that? Can't we put it out?"

"Let's get through with this job first," replied Arcot somewhat tersely. "The discussion comes after."

The bodies of the invaders were gone, so they could not examine them now. That was a matter for the doctors and biologists, anyway. The engines were their main interest, huge things which overshadowed everything about them.

It must have been the concealment afforded by the engines that permitted three of the enemy to get so close. The only warning the Terrestrians had was a faint pink haze as they stepped around the corner of an engine; and a sudden feeling of faintness swept over them. They leaped back, out of sight, peering around the corner with nerves and muscles tensed. There was no sign of movement.

As they watched, they saw a pallid hand reaching out with a ray gun; and Wade swiftly pointed his own weapon. There came a sudden crash of metal, a groan and quiet. Two other aliens leaped from behind the great engine just as the Terrestrians dodged further back; as swiftly, they too found concealment.

Arcot swung his ray up, and was about to pull the trigger that would send the huge engine toppling over upon them, when he saw that it was running. He thought of the unknown energies in the machine, the potential destruction, and he shook his head. Cautiously he looked around the edge of the towering mass, waiting—his beam flashed out, and there was a snapping sound as the ray caught a reaching hand and hurled its owner against a mighty transformer of some sort. For an instant the huge mass tottered, then was still. In the low concentration of power that Arcot had used, only a small portion had been touched, and the molecules of this portion had not been enough to tip over its tremendous weight.

Only one enemy remained; and Arcot learned swiftly that he was still in action, for before he could dodge back there came that now-familiar pink haziness. It touched Arcot's hand, outstretched as it had been when he fired, and a sudden numbness came over it. His pistol hand seemed to lose all feeling of warmth or cold. It was there; he could still feel the weapon's deadened weight. Reflex action hurled him back, his hand out of range of the ray. In seconds feeling began to return, and in less than ten his hand was normal again.

He turned to the others with a wry grin. "Whew—that was a narrow squeak! I must say their ray is a gentlemenly sort of thing. It either kills you, or doesn't injure you at all. There it goes again!"

A shaft of pink radiance reached the end of the engine, just grazing it, evidently absorbed by its mass. "Pinning us down," Wade grated. They certainly couldn't step out into the open space—but they couldn't stay where they were indefinitely, either. Reinforcements might arrive!

"Look," Wade pointed with his pistol, "he's under that big metal bar—up there in the roof—see it? I'll pull it down; he may get nervous and come into sight." Swiftly Arcot sprang forward and caught his arm.

"Lord—don't do that, Wade—there's too much stuff here that we don't know anything about. Too much chance of your smashing us with him. I'm going to try to get around to the other side of this machine and see what I can do, while you fellows keep him occupied."

Arcot disappeared around the black humming giant. Interminably the others waited for something to happen; then suddenly the beam that had been playing at irregular intervals across the end of the machine, swung quickly to the other side; and simultaneously another ray seemed to leap from the machine itself. They met and crossed. There came a momentary crashing arc, then both went dead, as the apparatus that generated them blew out under terrific overload.

The invader evidently carried a spare, for the watchers saw him dart from concealment, clawing at his pocket pouch. They turned their rays on him, and just as his projector came free, a ray hurled him violently to the left. He crashed into a huge motor, and the result was not nice.

The projector had been jerked from his hand and lay off to the side. Arcot ran to it and picked it up just as they heard the Lieutenant call an alarmed inquiry.

"I think we're okay now," Arcot answered. "I hope there are no more—but by all means stay where you are, and use as little power as possible in blowing that flame outside. It uses up the atmosphere of the ship, and though we don't need it, I think we'd better take things easy. Call us if anything looks odd to you."

For several minutes the three scientists looked about them in awe-struck wonder. They were the first men of Earth to see the driving equipment of one of the tremendous Kaxorian planes, and they felt tiny beside its great bulk; but now, as they examined this engine room, they realized that even the huge plane shrank into insignificance beside this interstellar cruiser.

All about them loomed the great rounded backs of giant electric motor-generators of some sort. Across the roof ran a network of gigantic metal bars, apparently conductors, but so large that they suggested heavy structural members. The machines they ran into loomed fully thirty feet into the air; they were longer than cylinders, thirty feet in diameter, and there was a group of four main machines fully a hundred twenty feet long! There were many smaller mechanisms—yet these smaller ones would easily have constituted a complete power supply for the average big city. Along each wall ran a bank of transformers, cast in the same heroic mold. These seemed connected with the smaller machines, there being four conductors leading into each of the minor units, two intake, and two, apparently, output leads, suggesting rotary converters. The multiple units and the various types and sizes of transformers made it obvious that many different frequencies were needed. Some of the transformers had air cores, and led to machines surrounded with a silvery white metal instead of the usual iron. These, apparently, were generating current at an extremely high frequency.

"Well," Morey commented, "they ought to have power enough. But do you notice that those four main units have their leads radiating in different directions? The one on the left there seems to lead to that big power board at the front—or better, bow. I think it would be worth investigating."

Arcot nodded. "I had the same idea. You notice that two of the main power units are still working, but that those other two have stopped? Probably the two dead ones have something to do with the motion of the ship. But there's one point I think is of even greater interest. All the machines we have seen, all the conspicuous ones, are secondary power sources. There are no primary sources visible. Notice that those two main conduits lead over to the right, and toward the bow. Let's check where they go to."

As they talked they followed the huge conductors back to their point of convergence. Suddenly they rounded one of the huge main power units, and saw before them, at the center of square formed by these machines, a low platform of transparent light-metal. At the exact center of this platform, which was twenty feet in diameter, there was a table, about seven feet across and raised about five feet above the level of the platform on stout light-metal legs. On the table were two huge cubes of solid silver, and into these cubes ran all the conductors they had seen.

In the space of about six inches left between the blocks of metal, there was a small box constructed of some strange new material. It was the most perfect reflecting surface that any of the men had ever imagined. Indeed, it was so perfect a reflector that they were unable to see it, but could detect its presence only by the mirror images, and the fact that it blotted out objects behind it.

Now they noticed that through the huge blocks of metal there were two small holes, and two thin wires of this same reflecting material led into those holes. The wires led directly up to the roof, and, suspended on three-foot hangers of the light-metal, continued on toward the bow.

Could this be the source of power for the entire ship? It seemed impossible, yet there were many other seeming impossible things here, among them that strangely reflecting matter.

There was a low railing about the central platform, apparently intended to keep observers at a safe distance, so they decided against any more detailed investigation. As they were about to discuss their unusual find, the Lieutenant called that he heard sounds behind him.

At once the three ran rapidly toward the narrow corridor that had given them entrance. The flaming gas was still shooting through the hole in the wall of the ship, and the rush of air through the corridor made it difficult to hear any sounds there, and exceedingly difficult to walk.

"Turn on more power, Lieutenant, and see if we can't draw out the enemy," suggested Arcot, while they braced themselves around the tube exit.

As the Patrolman increased the power of his beam, the moan of the air through the corridor increased suddenly to a terrific roar, and a cyclonic gale swept through. But none of the invaders were drawn out.

After the Lieutenant had shut off the blast from his pistol at Arcot's signal, the latter said: "I don't think anything less than a war tank could stand that pressure. It's probable that we'll be attacked if we stay here much longer, though—and we may not be able to get out at all. I think, Lieutenant, I'll ask you to stay here while we go out and get the ship ready to leave." He paused, grinning. "Be sure to keep that flame outside. You'll be in the position of Hercules after Atlas left him holding the skies on his shoulders. You can't shut off the ray for long or we'll have a first-rate explosion. We'll signal when we're ready by firing a revolver, and you make it to the ship as fast as you can travel."

Arcot's expression became solemn. "We'll have to carry Wright back to the ship. He was a brave man, and he certainly deserves burial in the soil of his own world. And, Morey, we'll have to look up his family. Your father's company will have to take care of them if they need help."

Slowly the men forced their way back toward their ship, fighting against the roaring column of air, their burden hindering them somewhat; but at last they reached the open tunnel. Even here the air was in violent motion.

They got into their boat as quickly as possible, and set the controls for reverse flight. Then Wade fired the signal shot. In moments they saw Lieutenant Greer bucking against the current of air, continuing under its own momentum.

By the time he was in the ship an ominous calm had fallen. Swiftly they sped down the corridor, and had almost reached the open air, when suddenly there was a dull rumble behind them, and they were caught on a wave of pressure that hurled them along at terrific speed. In a flash they sped into the open air, the great tunnel with its thick walls and flared opening acting like a gigantic blunderbus, with the ship as its bullet. Arcot made no attempt to slow down the little craft, but pressed his foot heavily on the vertical accelerator. The ship rocketed up with terrific speed, and the acceleration pinned the men down to their seats with tripled weight.

Anxiously they watched the huge invader as they sped away from it. At Arcot's direction Morey signaled the other groups of scientists to get out of danger with all speed, warning of the impending blow-up. As the moments sped by the tension mounted. Arcot stared fixedly into the screen before him, keeping the giant space ship in focus. As they sped mile upon miles away from it, he began to relax a bit.

Not a word was spoken as they watched and waited. Actually, very little time passed before the explosion, but to the watchers the seconds dragged endlessly. Then at twenty-seven miles, the screen flared into a sheet of blinding white radiance. There was a timeless instant—then a tremendous wave of sound, a roaring, stunning concussion smote the ship, shaking it with unrestrained fury—to cease as abruptly as it came.

Immediately they realized the reason. They were rushing away from the explosion faster than the sound it made, hence could not hear it. After the first intolerable flash, details became visible. The great ship seemed to leap into countless tremendous fragments, each rushing away from the point of the blow-up. They did not go far; the force was not sustained long enough, nor was it great enough to overcome the inertia of so vast a mass for more than moments. Huge masses rained to earth, to bury themselves in the soil.

There came a momentary lull. Then suddenly, from the mass which evidently held the wrecked engine room, there shot out a beam of intense white light that swept around in a wide, erratic arc. Whatever it touched fused instantly into a brilliantly glowing mass of liquid incandescence. The field itself, fragments of the wreckage, fused and mingled under its fury. The beam began to swing, faster and faster, as the support that was holding it melted; then abruptly it turned upon itself. There came a sudden blast of brilliance to rival that of the sun—and the entire region became a molten lake. Eyes streaming, temporarily blinded, the men turned away from the screen.

"That," said Arcot ruefully, "is that! It seems that our visitors don't want to leave any of their secrets lying around for us to investigate. I've an idea that all the other wrecks will go like this one did." He scowled. "You know, we really didn't learn much. Guess we'd better call the headquarters ship and ask for further instructions. Will you attend to it, Lieutenant Greer?"



III

Swiftly Arcot's sleek cruiser sped toward New York and the Arcot Laboratories. They had halted briefly at the headquarters ship of the Earth-Venus forces to report on their experience; and alone again, the three scientists were on their way home.

With their course set, Arcot spoke to the others. "Well, fellows, what are your opinions on—what we've seen? Wade, you're a chemist—tell us what you think of the explosion of the ship, and of the strange color of our molecular ray in their air."

Wade shook his head doubtfully. "I've been trying to figure it out, and I can't quite believe my results. Still, I can't see any other explanation. That reddish glow looked like hydrogen ions in the air. The atmosphere was certainly combustible when it met ours, which makes it impossible for me to believe that their air contained any noticeable amount of oxygen, for anything above twenty per cent oxygen and the rest hydrogen would be violently explosive. Apparently the gas had to mix liberally with our air to reach that proportion. That it didn't explode when ionized, showed the absence of hydro-oxygen mixture.

"All the observed facts except one seem to point to an atmosphere composed largely of hydrogen. That one—there are beings living in it! I can understand how the Venerians might adapt to a different climate, but I can't see how anything approaching human life can live in an atmosphere like that."

Arcot nodded. "I have come to similar conclusions. But I don't see too much objection to the thought of beings living in an atmosphere of hydrogen. It's all a question of organic chemistry. Remember that our bodies are just chemical furnaces. We take in fuel and oxidize it, using the heat as our source of power. The invaders live in an atmosphere of hydrogen. They eat oxidizing fuels, and breathe a reducing atmosphere; they have the two fuel components together again, but in a way different from our method. Evidently, it's just as effective. I'm sure that's the secret of the whole thing."

"Sounds fairly logical." Wade agreed. "But now I have a question for you. Where under the sun did these beings come from?"

Arcot's reply came slowly. "I've been wondering the same thing. And the more I wonder, the less I believe they did come from—under our sun. Let's eliminate all the solar planets—we can do that at one fell swoop. It's perfectly obvious that those ships are by no means the first crude attempts of this race to fly through space. We're dealing with an advanced technology. If they have had those ships even as far away as Pluto, we should certainly have heard from them by now.

"Hence, we've got to go out into interstellar space. You'll probably want to ram some of my arguments down my throat—I know there is no star near enough for the journey to be made in anything less than a couple of generations by all that's logical; and they'd freeze in the interstellar cold doing it. There is no known star close enough—but how about unknowns?"

"What have they been doing with the star?" Morey snorted. "Hiding it behind a sun-shade?"

Arcot grinned. "Yes. A shade of old age. You know a sun can't radiate forever; eventually they die. And a dead sun would be quite black, I'm sure."

"And the planets that circle about them are apt to become a wee bit cool too, you know."

"Agreed," said Arcot, "and we wouldn't be able to do much about it. But give these beings credit for a little higher order of intelligence. We saw machines in that space ship that certainly are beyond us! They are undoubtedly heating their planets with the same source of energy with which they are running their ships.

"I believe I have confirmation of that statement in two things. They are absolutely colorless; they don't even have an opaque white skin. Any living creature exposed to the rays of a sun, which is certain to emit some chemical rays, is subject to coloration as a protection against those rays. The whites, who have always lived where sunlight is weakest, have developed a skin only slightly opaque. The Orientals, who live in more tropical countries, where less clothes and more sun is the motto, have slightly darker skins. In the extreme tropics Nature has found it necessary to use a regular blanket of color to stop the rays. Now extrapolating the other way, were there no such rays, the people would become a pigmentless race. Since most proteins are rather translucent, at least when wet, they would appear much as these beings do. Remember, there are very few colored proteins. Hemoglobin, such as in our blood, and hemocyanin, like that in the blue blood of the Venerians, are practically unique in that respect. For hydrogen absorption, I imagine the blood of these creatures contains a fair proportion of some highly saturated compound, which readily takes on the element, and gives it up later.

"But we can kick this around some more in the lab."

Before starting for New York, Arcot had convinced the officer in charge that it would be wise to destroy the more complete of the invaders' ships at once, lest one of them manage to escape. The fact that none of them had any rays in operation was easily explained; they would have been destroyed by the Patrol if they had made any show of weapons. But they might be getting some ready, to be used in possible escape attempts. The scientists were through with their preliminary investigations. And the dismembered sections would remain for study, anyway.

The ships had finally been rayed apart, and when the three had left, their burning atmosphere had been sending mighty tongues of flame a mile or more into the air. The light gas of the alien atmosphere tended to rise in a great globular cloud, a ball that quickly burned itself out. It had not taken long for the last of the machines to disintegrate under the rays. There would be no more trouble from them, at any rate!

Now Morey asked Arcot if he thought that they had learned all they could from the ships; would it not have been wiser to save them, and investigate more fully later, taking a chance on stopping any sudden attack by surviving marauders by keeping a patrol of Air Guards there.

To which Arcot replied, "I thought quite a bit before I suggested their destruction, and I conferred for a few moments with Forsyth, who's just about tops in biology and bacteriology. He said that they had by no means learned as much as they wished to, but they'd been forced to leave in any event. Remember that pure hydrogen, the atmosphere we were actually living in while on the ship, is quite as inert as pure oxygen—when alone. But the two get very rough when mixed together. The longer those ships lay there the more dangerously explosive they became. If we hadn't destroyed them, they would have wrecked themselves. I still think we followed the only logical course.

"Dr. Forsyth mentioned the danger of disease. There's a remote possibility that we might be susceptible to their germs. I don't believe we would be, for our chemical constitution is so vastly different. For instance, the Venerians and Terrestrians can visit each other with perfect freedom. The Venerians have diseases, and so do we, of course; but there are things in the blood of Venerians that are absolutely deadly to any Terrestrian organism. We have a similar deadly effect on Venerian germs. It isn't immunity—it's simply that our respective constitutions are so different that we don't need immunity. Similarly, Forsyth thinks we would be completely resistant to all diseases brought by the invaders. However, it's safer to remove the danger, if any, first, and check afterward."

The three men sped rapidly back to New York, flying nearly sixty miles above the surface of the Earth, where there would be no interfering traffic, till at length they were above the big city, and dropping swiftly in a vertical traffic lane.

Shortly thereafter they settled lightly in the landing cradle at the Arcot Laboratories. Arcot's father, and Morey's, were there, anxiously awaiting their return. The elder Arcot had for many years held the reputation of being the nation's greatest physicist, but recently he had lost it—to his son. Morey Senior was the president and chief stockholder in the Transcontinental Air Lines. The Arcots, father and son, had turned all their inventions over to their close friends, the Moreys. For many years the success of the great air lines had been dependent in large part on the inventions of the Arcots; these new discoveries enabled them to keep one step ahead of competition, and as they also made the huge transport machines for other companies, they drew tremendous profits from these mechanisms. The mutual interest, which had begun as a purely financial relationship, had long since become a close personal friendship.

As Arcot stepped from his speedster, he called immediately to his father, telling of their find, the light-matter plate.

"I'll need a handling machine to move it. I'll be right back." He ran to the elevator and dropped quickly to the heavy machinery lab on the lower floor. In a short time he returned with a tractor-like machine equipped with a small derrick, designed to get its power from the electric mains. He ran the machine over to the ship. The others looked up as they heard the rumble and hum of its powerful motor. From the crane dangled a strong electro-magnet.

"What's that for?" asked Wade, pointing to the magnet. "You don't expect this to be magnetic, do you?"

"Wait and see!" laughed Arcot, maneuvering the handling machine into position. One of the others made contact with the power line, and the crane reached into the ship, lowering the magnet to the plate of crystal. Then Arcot turned the power into the lifting motor. The hum rose swiftly in volume and pitch till the full load began to strain the cables. The motor whined with full power, the cables vibrating under the tension. The machine pulled steadily, until, to Arcot's surprise, the rear end of the machine rose abruptly from the floor, tipping forward.

"Well—it was magnetic, but how did you know?" asked the surprised Wade. Since the ship was made of the Venerian metal, coronium, which was only slightly magnetic, the plate was obviously the magnet's only load.

"Never mind. I'll tell you later. Get an I-beam, say about twenty feet long, and see if you can't help lift that crazy mass. I think we ought to manage it that way."

And so it proved. With two of them straddling the I-beam, the leverage was great enough to pull the plate out. Running it over to the elevator, they lowered the heavy mass, disconnected the cable, and rode down to Arcot's laboratory. Again the I-beam and handling machine were brought into play, and the plate was unloaded from the car. The five men gathered around the amazing souvenir from another world.

"I'm with Wade in wondering how you knew the plate was magnetic, son," commented the elder Arcot. "I can accept your explanation that the stuff is a kind of matter made of light, but I know you too well to think it was just a lucky guess. How did you know?"

"It really was pretty much of a guess, Dad, though there was some logic behind the thought. You ought to be able to trace down the idea! How about you, Morey?" Arcot smiled at his friend.

"I've kept discreetly quiet," replied Morey, "feeling that in silence I could not betray my ignorance, but since you ask me, I can guess too. I seem to recall that light is affected by a powerful magnet, and I can imagine that that was the basis for your guess. It has been known for many years, as far back as Clerk Maxwell, that polarized light can be rotated by a powerful magnet."

"That's it! And now we may as well go over the whole story, and tell Dad and your father all that happened. Perhaps in the telling, we can straighten out our own ideas a bit."

For the next hour the three men talked, each telling his story, and trying to explain the whys and wherefores of what he had seen. In the end all agreed on one point: if they were to fight this enemy, they must have ships that could travel though space with speed to match that of the invaders, ships with a self-contained source of power.

During a brief lull in the conversation, Morey commented rather sarcastically: "I wonder if Arcot will now kindly explain his famous invisible light, or the lost star?" He was a bit nettled by his own failure to remember that a star could go black. "I can't see what connection this has with their sudden attack. If they were there, they must have developed when the star was bright, and as a star requires millions of years to cool down, I can't see how they could suddenly appear in space."

Before answering, Arcot reached into a drawer of his desk and pulled out an old blackened briar pipe. Methodically he filled it, a thoughtful frown on his face; then carefully lighting it, he leaned back, puffing out a thin column of gray smoke.

"Those creatures must have developed on their planets before the sun cooled." He puffed slowly. "They are, then, a race millions of years old—or so I believe. I can't give any scientific reason for this feeling; it's merely a hunch. I just have a feeling that the invaders are old, older than our very planet! This little globe is just about two billion years old. I feel that that race is so very ancient they may well have counted the revolutions of our galaxy as, once every twenty or thirty million years, it swung about its center.

"When I looked at those great machines, and those comparatively little beings as they handled their projectors, they seemed out of place. Why?" He shrugged. "Again, just a hunch, an impression." He paused again, and the slow smoke drifted upward.

"If I'm granted the premise that a black, dead star is approaching the Solar System, then my theorizing may seem more logical. You agree?" The listeners nodded and Arcot continued. "Well—I had an idea—and when I went downstairs for the handling machine, I called the Lunar Observatory." He couldn't quite keep a note of triumph out of his voice. "Gentlemen—some of the planets have been misbehaving! The outermost planets, and even some of those closer to the sun have not been moving as they should. A celestial body of appreciable mass is approaching the System; though thus far nothing has been seen of the visitor!"

A hubbub of excited comment followed this startling revelation. Arcot quieted them with an upraised hand. "The only reason you and the world at large haven't heard about this as yet is the fact that the perturbation of the planets is so very slight that the astronomers figured they might have made an error in calculation. They're rechecking now for mistakes.

"To get back to my visualization—It must have been many millions of years ago that life developed on the planets of the black star, a warm sun then, for it was much younger. It was probably rather dim as suns go even its younger days. Remember, our own sun is well above average in brilliance and heat radiation.

"In those long-gone ages I can imagine a race much like ours developing, differing chemically, in their atmosphere of hydrogen; but the chemical body is not what makes the race, it's the thought process. They must have developed, and then as their science grew, their sun waned. Dimmer and dimmer it became, until their planets could not maintain life naturally. Then they had to heat them artificially. There is no question as to their source of power; they had to use the energy of matter—so called atomic energy—for no other source would be great enough to do what had to be done. It is probable that their science had developed this long before their great need arose.

"With this must also have come the process of transmutation, and the process they use in driving their interstellar cruisers. I am sure those machines are driven by material energy.

"But at last their star was black, a closed star, and their cold, black planets must circle a hot, black sun forever! They were trapped for eternity unless they found a way to escape to some other stellar system. They could not travel as fast as light, and they could escape only if they found some near-by solar system. Their star was dead—black. Let's call it Nigra—the Black One—since like every other star it should have a name. Any objection?"

There was none, so Arcot continued:

"Now we come to an impossibly rare coincidence. That two suns in their motion should approach each other is beyond the point of logic. That both suns have a retinue of planets approaches the height of the ridiculous. Yet that is what is happening right now. And the Nigrans—if that's the correct term—have every intention of taking advantage of the coincidence. Since our sun has been visible to them for a long, long time, and the approaching proximity of the suns evident, they had lots of time to prepare.