The Black Star Passes

by Jr. John W. Campbell

THE BLACK STAR PASSES

PROLOGUE

Taj Lamor gazed steadily down at the vast dim bulk of the ancient city spread out beneath him. In the feeble light of the stars its mighty masses of up-flung metal buildings loomed strangely, like the shells of some vast race of crustacea, long extinct. Slowly he turned, gazing now out across the great plaza, where rested long rows of slender, yet mighty ships. Thoughtfully he stared at their dim, half-seen shapes.

Taj Lamor was not human. Though he was humanoid, Earth had never seen creatures just like him. His seven foot high figure seemed a bit ungainly by Terrestrial standards, and his strangely white, hairless flesh, suggesting unbaked dough, somehow gave the impression of near-transparency. His eyes were disproportionately large, and the black disc of pupil in the white corneas was intensified by contrast. Yet perhaps his race better deserved the designation homo sapiens than Terrestrians do, for it was wise with the accumulated wisdom of uncounted eons.

He turned to the other man in the high, cylindrical, dimly lit tower room overlooking the dark metropolis, a man far older than Taj Lamor, his narrow shoulders bent, and his features grayed with his years. His single short, tight-fitting garment of black plastic marked him as one of the Elders. The voice of Taj Lamor was vibrant with feeling:

“Tordos Gar, at last we are ready to seek a new sun. Life for our race!”

A quiet, patient, imperturbable smile appeared on the Elder's face and the heavy lids closed over his great eyes.

“Yes,” he said sadly, “but at what cost in tranquility! The discord, the unrest, the awakening of unnatural ambitions—a dreadful price to pay for a questionable gain. Too great a price, I think.” His eyes opened, and he raised a thin hand to check the younger man's protest. “I know—I know—in this we do not see as one. Yet perhaps some day you will learn even as I have that to rest is better than to engage in an endless struggle. Suns and planets die. Why should races seek to escape the inevitable?” Tordos Gar turned slowly away and gazed fixedly into the night sky.

Taj Lamor checked an impatient retort and sighed resignedly. It was this attitude that had made his task so difficult. Decadence. A race on an ages-long decline from vast heights of philosophical and scientific learning. Their last external enemy had been defeated millennia in the past; and through easy forgetfulness and lack of strife, ambition had died. Adventure had become a meaningless word.

Strangely, during the last century a few men had felt the stirrings of long-buried emotion, of ambition, of a craving for adventure. These were throwbacks to those ancestors of the race whose science had built their world. These men, a comparative handful, had been drawn to each other by the unnatural ferment within them; and Taj Lamor had become their leader. They had begun a mighty struggle against the inertia of ages of slow decay, had begun a search for the lost secrets of a hundred-million-year-old science.

Taj Lamor raised his eyes to the horizon. Through the leaping curve of the crystal clear roof of their world glowed a blazing spot of yellow fire. A star—the brightest object in a sky whose sun had lost its light. A point of radiance that held the last hopes of an incredibly ancient race.

The quiet voice of Tordos Gar came through the semidarkness of the room, a pensive, dreamlike quality in its tones.

“You, Taj Lamor, and those young men who have joined you in this futile expedition do not think deeply enough. Your vision is too narrow. You lack perspective. In your youth you cannot think on a cosmic scale.” He paused as though in thought, and when he continued, it seemed almost as though he were speaking to himself.

“In the far, dim past fifteen planets circled about a small, red sun. They were dead worlds—or rather, worlds that had not yet lived. Perhaps a million years passed before there moved about on three of them the beginnings of life. Then a hundred million years passed, and those first, crawling protoplasmic masses had become animals, and plants, and intermediate growths. And they fought endlessly for survival. Then more millions of years passed, and there appeared a creature which slowly gained ascendancy over the other struggling life forms that fought for the warmth of rays of the hot, red sun.

“That sun had been old, even as the age of a star is counted, before its planets had been born, and many, many millions of years had passed before those planets cooled, and then more eons sped by before life appeared. Now, as life slowly forced its way upward, that sun was nearly burned out. The animals fought, and bathed in the luxury of its rays, for many millennia were required to produce any noticeable change in its life-giving radiations.

“At last one animal gained the ascendancy. Our race. But though one species now ruled, there was no peace. Age followed age while semi-barbaric peoples fought among themselves. But even as they fought, they learned.

“They moved from caves into structures of wood and stone—and engineering had its beginning. With the buildings came little chemical engines to destroy them; warfare was developing. Then came the first crude flying-machines, using clumsy, inefficient engines. Chemical engines! Engines so crude that one could watch the flow of their fuel! One part in one hundred thousand million of the energy of their propellents they released to run the engines, and they carried fuel in such vast quantities that they staggered under its load as they left the ground! And warfare became world-wide. After flight came other machines and other ages. Other scientists began to have visions of the realms beyond, and they sought to tap the vast reservoirs of Nature's energies, the energies of matter.

“Other ages saw it done—a few thousand years later there passed out into space a machine that forced its way across the void to another planet! And the races of the three living worlds became as one—but there was no peace.

“Swiftly now, science grew upon itself, building with ever faster steps, like a crystal which, once started, forms with incalculable speed.

“And while that science grew swiftly greater, other changes took place, changes in our universe itself. Ten million years passed before the first of those changes became important. But slowly, steadily our atmosphere was drifting into space. Through ages this gradually became apparent. Our worlds were losing their air and their water. One planet, less favored than another, fought for its life, and space itself was ablaze with the struggles of wars for survival.

“Again science helped us. Thousands of years before, men had learned how to change the mass of matter into energy, but now at last the process was reversed, and those ancestors of ours could change energy into matter, any kind of matter they wished. Rock they took, and changed it to energy, then that energy they transmuted to air, to water, to the necessary metals. Their planets took a new lease of life!

“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.

“I believe this expedition was just an exploratory one; and if they can send such huge machines and so many of them, for mere exploration, I'm sure they must have quite a fleet to fight with.

“We know little about their weapons. They have that death ray, but it's not quite as deadly as we might have feared, solely because our ships could outmaneuver them. Next time, logically, they'll bring with them a fleet of little ships, carried in the bellies of those giants, and they'll be a real enemy. We'll have to anticipate their moves and build to circumvent them.

“As for their ray, I believe I have an idea how it works. You're all familiar with the catalytic effects of light. Hydrogen and chlorine will stand very peacefully in the same jar for a long time, but let a strong light fall on them, and they combine with terrific violence. This is the catalytic effect of a vibration, a wave motion. Then there is such a thing as negative catalysis. In a certain reaction, if a third element or compound is introduced, all reaction is stopped. I believe that's the principle of the Nigran death ray; it's a catalyst that simply stops the chemical reactions of a living body, and these are so delicately balanced that the least resistance will upset them.”

Arcot halted, and sat puffing furiously for a moment. During his discourse the pipe had died to an ember; with vigorous puffing he tried to restore it. At last he had it going and continued.

“What other weapons they have we cannot say. The secret of invisibility must be very old to them. But we'll guard against the possibility by equipping our ships against it. The only reason the patrol ships aren't equipped already is that invisibility is useless with modern criminals; they all know the secret and how to fight it.”

Morey interrupted with a question.

“Arcot, it's obvious that we have to get out into space to meet the enemy—and we'll have to have freedom of movement there. How are we going to do it? I was wondering if we could use Wade's system of storing the atomic hydrogen in solution. That yields about 100,000 calories for every two grams, and since this is a method of storing heat energy, and your molecular motion director is a method of converting heat into mechanical work with 100 per cent efficiency, why not use that? All we need, really, is a method of storing heat energy for use while we're in space.”

Arcot exhaled slowly before answering, watching the column of smoke vanish into the air.

“I thought of that, and I've been trying to think of other, and if possible, better, cheaper, and quicker ways of getting the necessary power.

“Let's eliminate the known sources one by one. The usual ones, the ones men have been using for centuries, go out at once. The atomic hydrogen reaction stores more energy per gram than any other chemical reaction known. Such things as the storage battery, the electro-static condenser, the induction coil, or plain heat storage, are worthless to us. The only other method of storing energy we know of is the method used by the Kaxorians in driving their huge planes.

“They use condensed light-energy. This is efficient to the ultimate maximum, something no other method can hope to attain. Yet they need huge reservoirs to store it. The result is still ineffective for our purpose; we want something we can put in a small space; we want to condense the light still further. That will be the ideal form of energy storage, for then we will be able to release it directly as a heat ray, and so use it with utmost efficiency. I think we can absorb the released energy in the usual cavity radiator.”

A queer little smile appeared on Arcot's face. “Remember—what we want is light in a more condensed form, a form that is naturally stable, and that does not need to be held in a bound state, but actually requires urging to bring about the release of energy. For example—”

A shout from Wade interrupted him. “That's really rare! Whoo—I have to hand it to you! That takes all the prizes!” He laughed delightedly. In puzzled wonder Morey and the two older men looked at him, and at Arcot who was grinning broadly now.

“Well, I suppose it must be funny,” Morey began, then hesitated. “Oh—I see—say, that is good!” He turned to his father. “I see now what he's been driving at. It's been right here under our noses all the time.

“The light-matter windows we found in the wrecked enemy ships contain enough bound light-energy to run all the planes we could make in the next ten years! We're going to have the enemy supply us with power we can't get in any other way. I can't decide, Arcot, whether you deserve a prize for ingenuity, or whether we should receive booby-prizes for our stupidity.”

Arcot Senior smiled at first, then looked dubiously at his son.

“There's definitely plenty of the right kind of energy stored there—but as you suggested, the energy will need encouragement to break free. Any ideas?”

“A couple. I don't know how they'll work, of course; but we can try.” Arcot puffed at his pipe, serious now as he thought of the problems ahead.

Wade interposed a question. “How do you suppose they condense that light energy in the first place, and, their sun being dead, whence all the light? Back to the atom, I suppose.”

“You know as much as I do, of course, but I'm sure they must break up matter for its energy. As for the condensation problem, I think I have a possible solution of that too—it's the key to the problem of release. There's a lot we don't know now—but we'll have a bigger store of knowledge before this war is over—if we have anything at all!” he added grimly. “It's possible that man may lose knowledge, life, his planets and sun—but there's still plenty of hope. We're not finished yet.”

“How do you think they got their energy loose?” asked Wade. “Do you think those big blocks of what appeared to be silver were involved in the energy release?”

“Yes, I do. Those blocks were probably designed to carry away the power once it was released. How the release was accomplished, though, I don't know. They couldn't use material apparatus to start their release of material energy; the material of the apparatus might 'catch fire' too. They had to have the disintegrating matter held apart from all other matter. This was quite impossible, if you are going to get the energy away by any method other than by the use of fields of force. I don't think that is the method. My guess is that a terrific current of electricity would accomplish it if anything would.

“How then are we going to get the current to it? The wires will be subject to the same currents. Whatever they do to the matter involved, the currents will do to the apparatus—except in one case. If that apparatus is made of some other kind of matter, then it wouldn't be affected. The solution is obvious. Use some of the light-matter. What will destroy light-matter, won't destroy electricity-matter, and what will destroy electricity-matter, won't disturb light-matter.

“Do you remember the platform of light-metal, clear as crystal? It must have been an insulating platform. What we started as our assumptions in the case of the light-metal, we can now carry further. We said that electricity-metals carried electricity, so light-metals would carry or conduct light. Now we know that there is no substance which is transparent to light, that will carry electricity by metallic conduction. I mean, of course, that there is no substance transparent to light, and at the same time capable of carrying electricity by electronic transmission. True, we have things like NaCl solutions in ordinary H₂O which will carry electricity, but here it's ionic conduction. Even glass will carry electricity very well when hot; when red hot, glass will carry enough electricity to melt it very quickly. But again, glass is not a solid, but a viscous liquid, and it is again carried by ionic conduction. Iron, copper, sodium, silver, lead—all metals carry the current by means of electron drift through the solid material. In such cases we can see that no transparent substance conducts electricity.

“Similarly, the reverse is true. No substance capable of carrying electricity by metallic conduction is transparent. All are opaque, if in any thickness. Of course, gold is transparent when in leaf form—but when it's that thin it won't conduct very much! The peculiar condition we reach in the case of the invisible ship is different. There the effects are brought about by the high frequency impressed. But you get my point.

“Do you remember those wires that we saw leading to that little box of the reflecting material? So perfectly reflecting it was that we didn't see it. We only saw where it must be; we saw the light it reflected. That was no doubt light-matter, a non-metal, and as such, non-conductive to light. Like sulphur, an electric non-metal, it reflected the base of which it was formed. Sulphur reflects the base of which it was formed. Sulphur reflects electricity and—in the crystalline form—passes light. This light-non-metal did the same sort of thing; it reflected light and passed electricity. It was a conductor.

“Now we have the things we need, the matter to disintegrate, and the matter to hold the disintegrating material in. We have two different types of matter. The rest is obvious—but decidedly not easy. They have done it, though; and after the war is over, there should be many of their machines drifting about in space waiting to give up their secrets.”

Arcot Senior clapped his son on the back. “A fair foundation on which to start, anyway. But I think it's time now that you got working on your problem; and since I'm officially retired, I'm going downstairs. You know I'm working in my lab on a method to increase the range and power of your projector for the molecular motion field. Young Norris is helping me, and he really has ideas. I'll show you our math later.”

The party broke up, the three younger men staying in their own labs, the older men leaving.

---

IV

The three immediately set to work. At Arcot's suggestion, Wade and Morey attacked the plate of crystal in an attempt to tear off a small piece, on which they might work. Arcot himself went into the televisophone room and put through a second call to the Tychos Observatory, the great observatory that had so recently been established on the frigid surface of the Moon. The huge mirror, twenty feet in diameter, allowed an immense magnification, and stellar observations were greatly facilitated, for no one bothered them, and the “seeing” was always perfect.

However, the great distance was rather a handicap to the ordinary televisophone stations, and all calls put through to the astronomers had to be made through the powerful sending station in St. Louis, where all interplanetary messages were sent and received, while that side of the Earth was facing the station; and from Constantinople, when that city faced the satellite. These stations could bridge the distance readily and clearly.

For several minutes Arcot waited while connections were being made with the Moon; then for many more minutes he talked earnestly with the observer in this distant station, and at last satisfied, he hung up.

He had outlined his ideas concerning the black star, based upon the perturbation of the planets; then he had asked them to investigate the possibilities, and see if they could find any blotting out of stars by a lightless mass.

Finally he returned to Morey and Wade who had been working on the crystal plate. Wade had an expression of exasperation on his face, and Morey was grinning broadly.

“Hello, Arcot—you missed all the fun! You should have seen Wade's struggle with that plate!” The plate, during his absence, had been twisted and bent, showing that it had undergone some terrific stresses. Now Wade began to make a series of highly forceful comments about the properties of the plate in language that was not exactly scientific. It had value, though, in that it seemed to relieve his pent-up wrath.

“Why, Wade, you don't seem to like that stuff. Maybe the difficulty lies in your treatment, rather than in the material itself. What have you tried?”

“Everything! I took a coronium hack saw that will eat through molybdenum steel like so much cheese, and it just wore its teeth off. I tried some of those diamond rotary saws you have, attached to an electric motor, and it wore out the diamonds. That got my goat, so I tried using a little force. I put it in the tension testing machine, and clamped it—the clamp was good for 10,000,000 pounds—but it began to bend, so I had to quit. Then Morey held it with a molecular beam, and I tried twisting it. Believe me, it gave me real pleasure to see that thing yield under the pressure. But it's not brittle; it merely bends.

“And I can't cut it, or even get some shavings off the darned thing. You said you wanted to make a Jolly balance determination of the specific gravity, but the stuff is so dense you'd need only a tiny scrap—and I can't break it loose!” Wade looked at the plate in thorough disgust.

Arcot smiled sympathetically; he could understand his feelings, for the stuff certainly was stubborn. “I'm sorry I didn't warn you fellows about what you'd run into, but I was so anxious to get that call through to the Moon that I forgot to tell you how I expected to make it workable. Now, Wade, if you'll get another of those diamond-tooth rotary saws, I'll get something that may help. Put the saw on the air motor. Use the one made of coronium.”

Wade looked after the rapidly disappearing Arcot with raised eyebrows, then, scratching his head, he turned and did as Arcot had asked.

Arcot returned in about five minutes with a small handling machine, and a huge magnet. It must have weighed nearly half a ton. This he quickly connected to the heavy duty power lines of the lab. Now, running the handling machine into position, he quickly hoisted the bent and twisted plate to the poles of the magnet, with the aid of the derrick. Then backing the handling machine out of the way, he returned briskly to his waiting associates.

“Now we'll see what we will see!” With a confident smile Arcot switched on the current of the big magnet. At once a terrific magnetic flux was set up through the light-metal. He took the little compressed-air saw, and applied it to the crystal plate. The smooth hiss of the air deepened to a harsh whine as the load came on it, then the saw made contact with the refractory plate.

Unbelievingly Wade saw the little diamond-edge saw bite its way slowly but steadily into the plate. In a moment it had cut off a little corner of the light-matter, and this fell with a heavy thud to the magnet pole, drawn down by the attraction of the magnet and by gravity.

Shutting off the magnet, Arcot picked up a pair of pliers and gripped the little fragment.

“Whew—light-metal certainly isn't light metal! I'll bet this little scrap weights ten pounds! We'll have to reduce it considerably before we can use it. But that shouldn't be too difficult.”

By using the magnet and several large diamond faceplates they were able to work the tough material down to a thin sheet; then with a heavy press, they cut some very small fragments, and with these, determined the specific gravity.

“Arcot,” Wade asked finally, “just how does the magnet make that stuff tractable? I'm not physicist enough to figure out what takes place inside the material.”

“Magnetism worked as it did,” Arcot explained, “because in this light-matter every photon is affected by the magnetism, and every photon is given a new motion. That stuff can be made to go with the speed of light, you know. It's the only solid that could be so affected. This stuff should be able, with the aid of a molecular motion beam, which will make all the photons move in parallel paths, to move at the full speed of each photon—186,000 miles a second. The tremendous speed of these individual photons is what makes the material so hard. Their kinetic impulse is rather considerable! It's the kinetic blow that the molecules of a metal give that keeps other metal from penetrating it. This simply gives such powerful impulse that even diamonds wouldn't cut it.

“You know that an iron saw will cut platinum readily, yet if both are heated to say, 1600 degrees, the iron is a liquid, and the platinum very soft—but now the platinum cuts through the iron!

“Heat probably won't have any effect on this stuff, but the action of the magnet on the individual photons corresponds to the effect of the heat on the individual atoms and molecules. The mass is softened, and we can work it. At least, that's the way I figure it out.

“But now, Wade, I wish you'd see if you can determine the density of the stuff. You're more used to those determinations and that type of manipulation than we are. When you get through, we may be able to show you some interesting results ourselves!”

Wade picked up a tiny chip of the light-metal and headed for his own laboratory. Here he set up his Jolly balance, and began to work on the fragment. His results were so amazing that he checked and rechecked his work, but always with the same answer. Finally he returned to the main lab where Arcot and Morey were busy at the construction of a large and complicated electro-static apparatus.

“What did you find?” called out Arcot, as he saw Wade reenter the room. “Hold your report a second and give us a hand here, will you? I have a laboratory scale apparatus of the type the Kaxorians used in the storage of light. They've known, ever since they began working with them, that their machines would release the energy with more than normal violence, if certain changes were made in them. That is, the light condenser, the device that stored the photons so close to each other, would also serve to urge them apart. I've made the necessary changes, and now I'm trying to set up the apparatus to work on solid light-matter. It was developed for gaseous material, and it's a rather tricky thing to change it over. But I think we've almost got it.

“Wade, will you connect that to the high frequency oscillator there—no—through that counterbalanced condenser. We may have to change the oscillator frequency quite a bit, but a variable condenser will do that.

“Now, what results did you get?”

Wade shook his head doubtfully. “We all know it's amazing stuff—and of course, it must be heavy—but still—well, anyway, I got a density of 103.5!”

“Whewww—103.5! Lord! That's almost five times as heavy as the heaviest metal hitherto known. There's about half a cubic foot of the material; that would mean about 4000 pounds for the whole mass, or two tons. No wonder we couldn't lift the plate!”

They stopped their work on the Kaxorian apparatus to discuss the amazing results of the density test, but now they fell to again, rapidly assembling the device, for each was a trained experimenter. With all but the final details completed, Arcot stood back and surveyed their handiwork.

“I think we'll have enough urge to cause disintegration right here,” he said, “but I want to make sure, and so, before we set up the case over it, I think we may as well put that big magnet in place, and have it there to help in the work of disintegration, if need be.”

At last the complete apparatus was set up, and the tiny bit of light-matter they were to work on was placed on the table of a powerful Atchinson projector microscope, the field of view being in the exact center of the field of both the magnet and the coil. Carefully, then, step by step, Arcot, Morey and Wade went over their work, checking and rechecking.

“Well, we're ready,” said Arcot finally, as he placed the projector screen in position and dimmed the lights in the room. A touch of the switch, and the projection screen was illuminated with the greatly enlarged image of the tiny scrap of light-metal.

With his hand on the switch, Arcot spoke to the other two. “I won't say there's no danger, since we haven't done this before; and if all the energy should be released at once, it'll blow the top out of the building. But I'm reasonably sure that it will work safely. Any objections?”

Wade shook his head, and Morey said: “I can't see any flaws in our work.”

Arcot nodded, and unconsciously tensing, he closed the switch. This put the powerful Arcot oscillator tubes into action, and the power was ready for application.

Slowly he closed the rheostat and put the power into the coil. The little sliver of metal on the slide seemed to throb a bit, and its outline grew hazy; but at last, with full power on, the release was so slow as to be imperceptible.

“Guess we need the magnet after all; I'll put it on this time.”

He opened the coil circuit and closed the magnet circuit at half voltage, then again he increased the current through the rheostat. This time the plate throbbed quite violently, it took the appearance of a bit of iodine. Dense vapors began pouring from it, and instantly those vapors became a blindingly brilliant flood of light. Arcot had snapped open the switch the moment he saw this display start, and it had had little time to act, for the instant the circuit was opened, it subsided. But even in that brief time, the light aluminum screen had suddenly become limp and slumped down, molten! The room was unbearably hot, and the men were half blinded by the intensity of the light.

“It works!” yelled Wade. “It works! That sure was hot, too—it's roasting in here.” He flung open a window. “Let's have some air.”

Arcot and Morey gripped hands with a broad grin. That display meant that Earth and Venus would have space ships with which to fight space ships. Reason enough for their joy.

Though they had made an unusual amount of progress already, there was still a great deal of development work to be done. Fuller was needed, Arcot decided, so he called the elder Morey and requested his services if he could be spared from his present work. He could, and would arrive later that day.

When Fuller appeared about mid-afternoon, he found the three friends already at work on the development of a more compact apparatus than the makeshift hookup used in making that first release mechanism.

“And so you can see,” said Arcot as he finished his summary of their work to that point, “we still have quite a job ahead of us. I'm now trying to find some data for you to work on, but I can tell you this: We'll need a ship that has plenty of strength and plenty of speed. There will be the usual power plant, of course; the generators, the power-tube board, and the electro-magnetic relays for the regular molecular motion controls. Then, in addition, we must have controls for the ray projector, though that must wait a while, for Dad is working on a method of doubling our range.... Oh yes, the driving units will be inside the ship now, for all our power will come from the energy of the light-matter.”

They spent the next hour in discussing the manifold details involved in the design of their space ship: the mechanism involved in transferring the light-energy to the drivers; a means of warming the ship in interstellar space; a main horizontal drive for forward and backward motion as well as braking; three smaller vertical power units to give them freedom of direction in climb or descent; other smaller horizontal power units for turning and moving sideways.

The ships, they decided, must be capable of six or seven thousand miles a second. They would need three types of ships: a small single-man speedster, without bunk or living quarters, simply a little power plant and weapon. Designed for speed and mobility, it would be very hard to hit, and because of its own offensive power would be dangerous to the enemy. They would need a fleet of mother ships—ships that would hold both the speedsters and their pilots—say thirty to a cruiser. There would also be some ten-man scouts, operating in the same manner as the larger cruisers, but with a smaller fleet of speedsters dependent on them.

“For defense,” Arcot concluded, “we'll have to depend on armor as heavy as we can make and still remain within the bounds of practical construction. I don't believe we'll be able to build up enough mass to insulate against their negative catalysis ray. We'll have to depend on mobility and offense.

“But now let's get back to work. I think, Fuller, that you might call in the engineers of all the big aircraft and machine tool manufacturers and fabricators, and have them ready to start work at once when the plans are finally drawn up. You'd better get in touch with the Venerian producers, too. Those new works in Sorthol, Kaxor, will certainly be able to help a lot.

“I suppose the Interplanetary Patrol men will have something to say, so they better be called in. Likewise the Venerian Council. Morey, maybe your dad can handle some of this.”

As one they arose and set to work on their respective tasks—the planning and building of the Earth-Venus war fleet.

---

V

Despite their utmost endeavor and the hard work of the industrial might of two worlds, it was nearly six weeks before the fleet had grown to a thing of importance. The tests to which they subjected the tiny speedsters had been more than satisfactory. They behaved wonderfully, shooting about at terrific speed, and with all the acceleration a pilot could stand. These speedsters were literally piloted projectiles, and their amazing mobility made them a powerful arm of offense.

There came into being a special corp dubbed, oddly enough, the “Rocket Squad”, a group of men who could stand plenty of “G's”. This “Rocket Squad” was composed solely of Terrestrians, for they were accustomed to the gravity of Earth and could stand greater acceleration strains than could the Venerians. The pick of the Air Patrol formed the nucleus of this new military organization; and in short order, so great is the appeal of the new and novel, the cream of the young men of the planet were competing for a place among the Rocketeers.

Each ship, both speedster and mother craft, was equipped with an invisibility locator, a sensitive short-wave directional receiver, that would permit the operator to direct his rays at invisible targets. The ships themselves could not be made invisible, since they depended in their very principle on the absorption of light-energy. If the walls of every part of the ship were perfectly transparent, they could absorb no energy at all, and they would still be plainly visible—even more so than before! They must remain visible, but they could also force the enemy to remain visible.

Each ten-man ship carried an old-fashioned cannon that was equipped to hurl cannisters carrying the luminous paint. They decided that these would have advantages, even if the invaders did not use invisibility, for in space a ship is visible only because it reflects or emits light. For this reason the ships were not equipped with any portholes except in the pilot room and at the observation posts. No light could escape. To reduce the reflection to the absolute minimum, the ships had each been painted with a 99% absorptive black. In space they would be exceedingly difficult targets.

The heating effect of the sun on the black pigment when near the great star was rather disagreeably intense, and to cool the speedsters they had installed molecular director power units, which absorbed the heat and used the energy to drive the ship. Heaters offset the radiation loss of the black surface when too far from the sun.

Each of the speedsters was equipped with a small machine-gun shooting luminous paint bullets. One of these, landing on another craft, made it visible for at least two hours, and since they could cover an area of about thirty feet, they were decidedly effective.

It was found that ray practice was rather complicated. The government had ranges set up in great mountain districts away from any valuable property, but they soon found that spatial warplay could not be carried on on Earth. The rays very quickly demolished the targets, and in a short time made good progress toward demolishing the mountains as well. The problem was solved by using the barren surface of the moon and the asteroid belt beyond Mars as a proving ground.

The ships were sent out in squadrons as fast as they could be finished and the men could be brought together and trained. They were establishing a great shield of ships across all that section of the system whence the Nigrans had appeared, and they hoped to intercept the next attack before it reached Earth, for they were certain the next attack would be in full force.

Arcot had gone to the conference held on Venus with the other men who had investigated the great wrecks, and each scientist had related his view of things and had offered suggestions. Arcot's idea of the black star was not very favorably received. As he later told Wade and Morey, who had not gone, there was good reason for their objection to his idea. Though the scientists were willing to admit that the invaders must have come from a great distance, and they agreed that they lived in an atmosphere of hydrogen, and judging from their pale skins, that they were not used to the rays of a sun, they still insisted on the theory of an outer planet of Sol.

“You remember,” explained Arcot, “several years ago there was considerable discussion about the existence of a planet still further out from the sun than Pluto. It is well known that there are a number of irregularities in the orbits of Neptune and Pluto that can't be caused by known planets, and an outer planet could have the necessary mass and orbit to account for them.

“This attack from outer space was immediately taken as proof of that theory, and it was very easily supported, too. My one good point that stood for any length of time under their attacks was the fact that those ships weren't developed in a year, nor a century, and that the chemical constitution of the men was so different. There were no new elements discovered, except the light-matter, but they are rather wondering about the great difference of earthly chemical constitution and the constitution of these invaders.

“They had one argument that was just about enough to throw mine out, though they pointed to the odds against the thing happening. You know, of course, how planets are formed? They are the results of tidal action on two passing suns.

“You can imagine two mighty stars careening through space and then drawing slowly nearer, till at last they come within a few billion miles of each other, and their gigantic masses reach out and bind them with a mighty chain of gravity. Their titanic masses swing about each other, each trying to pull free, and continue its path about the center of the galactic system. But as their huge bulks come nearer, the chains that bind them become stronger and stronger, and the tremendous pull of the one gargantuan fire ball on the other raises titanic tides of flame. Great streamers of gas shoot out, and all the space about is lighted by the flaming suns. The pull of gravity becomes more and more intense, and as the one circles the other, the tide is pulled up, and the mighty ball of fire, which, for all its existence has been practically motionless as far as rotation goes, begins to acquire a greater and greater rotational speed as the tidal drag urges it on. The flames begin to reach higher and higher, and the tides, now urged from the sun by centrifugal force, rise into an ever greater crest, and as the swinging suns struggle to break loose, the flaming gas is pulled up and up, and becomes a mighty column of fire, a column that reaches out across three—four—a dozen millions of miles of space and joins the two stars at last, as stalactites and stalagmites grow together. A flaming tie of matter joins them, two titanic suns, and a mighty rope of fire binds them, while far mightier chains of gravity hold them together.

“But now their original velocity reasserts itself, and having spiraled about each other for who can say how long—a year—a million years seems more probable—but still only an instant in the life of a star—they begin to draw apart, and the flaming column is stretched out, and ever thinner it grows, and the two stars at last separate. But now the gas will never fall back into the sun. Like some giant flaming cigar it reaches out into space and it will stay thus, for it has been set in rotation about the sun at such a speed as is needed to form an orbit. The giant mass of gas is, however, too cool to continue to develop energy from matter, for it was only the surface of the sun, and cool. As it cools still further, there appear in it definite condensations, and the beginnings of the planets are there. The great filament that stretched from the sun to sun was cigar-shaped, and so the matter is more plentiful toward the center, and larger planets develop. Thus Jupiter and Saturn are far larger than any of the others. The two ends are tapering, thus Earth is larger than Venus, which is larger than Mercury, and Uranus and Neptune are both smaller than Saturn, Pluto being smaller than either.

“Mars and the asteroids are hard to explain. Perhaps it is easier to understand when we remember that the planets thus formed must necessarily have been rotating in eccentric orbits when they were first born, and these planets came too near the sun while gaseous, or nearly so, and Mars lost much of its matter, while the other, which now exists only as the asteroids, broke up.

“But now that other flaming star has retired, wandering on through space. The star has left its traces, for behind it there are planets where none existed before. But remember that it, too, must have planets now.

“All this happened some 2,000 million years ago.

“But in order that it might happen, it requires that two stars pass within the relatively short distance of a few billion miles of each other. Space is not overcrowded with matter, you know. The density of the stars has been compared with twenty tennis balls roaming about 8,000-mile sphere that the Earth fills up—twenty tennis balls in some 270 billion cubic miles of space. Now imagine two of those tennis balls—with plenty of room to wander in—passing within a few yards of each other. The chances are about as good as the chances of two stars passing close enough to make planets.

“Now let us consider another possibility.

“The Black Star, as I told you, has planets. That means that it must have thus passed close to another star. Now we have it coming close to another sun that has been similarly afflicted. The chances of that happening are inconceivably small. It is one chance in billions that the planets will form. Two stars must pass close to each other, when they have all space to wander about in. Then those afflicted stars separate, and one of them passes close by a new star, which has thus been similarly afflicted with that one chance in billions—well, that is then a chance in billions of billions.

“So my theory was called impossible. I don't know but what it is. Besides, I thought of an argument the other men didn't throw at me. I'm surprised they didn't, too—the explanation of the strange chemical constitution of these men of a solar system planet would not be so impossible. It is quite possible that they live on a planet revolving about the sun which is, nevertheless, a planet of another star. It is quite conceivable to me that the chemical constitution of Neptune and Pluto will be found to be quite different from that of the rest of our planets. The two filaments drawn out from the suns may not have mingled, though I think they did, but it is quite conceivable that, just before parting, our sun tore one planet, or even two or three, from the other star.

“And that would explain these strange beings.

“My other ideas were accepted. The agreed-on plan for the release of energy, and the source of the power.” Arcot puffed on his pipe meditatively for several moments, then stood up and stretched.

“Ho—I wish they'd let me go on active duty with the space fleet! A scientific reputation can be an awful handicap at times,” he grinned. He had been rejected very emphatically when he had tried to enlist. The Interplanetary governments had stated flatly that he was too important as a scientist to be risked as a pilot of a space ship.

On two worlds the great construction plants were humming with activity. Civilian production of all but the barest essentials had been put aside for the duration of the emergency. Space ships were being turned out at top speed, getting their fuel from the wrecks of the invaders' cruisers. Each ship needed only a small amount of the light-metal, for the energy content was tremendous. And those ships had been gigantic.

Already there was a fleet of speedsters and mother ships out there in space, and with every passing hour others left the home planets, always adding to the fighting force that was to engage the attackers deep in space, where no stray ships might filter through to destroy the cities of Earth or Venus. Assembly lines were now turning out ships so rapidly that the training of their operators was the most serious problem. This difficulty had finally been overcome by a very abbreviated training course in the actual manipulation of the controls on the home planets, and subsequent training as the squadrons raced on their outward courses.

It was soon decided that there must be another service beside that of the ordinary ships. One plant was devoted to making huge interstellar liners. These giants, made on Venus, were nearly a quarter of a mile long, and though diminutive in comparison with the giant Nigran ships, they were still decidedly large. Twelve of these could be completed within the next month, it was found; and one was immediately set aside as an officers' headquarters ship. It was recognized that the officers must be within a few hundred thousand miles of the actual engagements, for decisions would have to be made without too much loss of time in the transmission of reports.

The ship must not be brought too near the front lest the officers be endangered and the entire engagement lost for want of the organizing central headquarters. The final solution had been the huge central control ship.

The other large vessels were to be used to carry food and supplies. They were not to enter the engagement, for their huge size would make them as vulnerable to the tiny darting mites of space as the Nigran ships had been to the Interplanetary Patrol. The little ships could not conveniently stock for more than a week of engagement, then drop back to these warehouses of space, and go forward again for action.

Throughout the long wait the officers of the Solarian forces organized their forces to the limit of their ability, planning each move of their attack. Space had been marked off into a great three-dimensional map, and each ship carried a small replica, the planets moving as they did in their orbits. The space between the planets was divided off into definite points in a series of Cartesian co-ordinates, the sun being the origin, and the plane of the elliptic being the X-Y plane.

The OX line was taken pointing toward one of the brightest of the fixed stars that was in the plane of the elliptic. The entire solar system was thus marked off as had been the planets long ages before, into a system of three dimensional latitude and longitude. This was imperative, in order to assure the easy location of the point of first attack, and to permit the entire fleet to come into position there. A scattered guard was to remain free, to avoid any false attacks and a later attack from a point millions of miles distant. Earth and Venus were each equipped with gigantic ray projectors, mighty weapons that could destroy anything, even a body as large as the Moon, at a distance of ten thousand miles. Still, a ship might get through, and with the death ray—what fearful toll might be exacted from a vast city such as Chicago—with its thirty millions! Or Karos, on Venus, with its fifteen and one half millions!

The tension became greater and greater as with each passing day the populace of two worlds awaited the call from the far-flung guard. The main bulk of the fleet had been concentrated in the center of their great spherical shell of ships. They could only wait—and watch—and prepare! Hundreds of miles apart, yet near enough so that no ship except perhaps a one-man craft could pass them undetected; and behind them were ships with delicate apparatus that could detect any foreign body of any size whatever within a hundred thousand miles of them.

The Solar System was prepared to repel boarders from the vast sea of space!

---

VI

Taj Lamor gazed down at the tremendous field below him. In it lay close packed a great mass of ships, a concourse of Titans of Space, dreadnoughts that were soon to set out to win—not a nation, not even a world, but to conquer a solar system, and to win for their owners a vast new sun, a sun that would light them and heat them for long ages to come.

Momentarily Taj Lamor's gaze followed the retreating figure of Tordos Gar, the Elder; a figure with stooped shoulders and bowed head. His quiet yet vibrant parting words still resounded in his ears:

“Taj Lamor, remember what I tell you. If you win this awful war—you lose. As will our race. Only if you lose will you win.”

With a frown Taj Lamor stared down at the vast metal hulls glistening softly in the dull light of far-off stars, the single brightly beaming star that was their goal, and the dim artificial lighting system. From the distance came to him the tapping and humming of the working machines below as they strove to put the finishing touches to the great ships.

He raised his eyes toward the far-off horizon, where a great yellow star flamed brilliantly against the black velvet of space. He thought of that planet where the sky had been blue—an atmosphere of such intensity that it colored the sky!

Thoughtfully he gazed at the flaming yellow point.

He had much to consider now. They had met a new race, barbarians in some ways, yet they had not forgotten the lessons they had learned; they were not decadent. Between his eon-old people and their new home stood these strange beings, a race so young that its age could readily be counted in millennia, but withal a strong, intelligent form of life. And to a race that had not known war for so many untold ages, it was an unthinkable thing that they must kill other living, intelligent beings in order that they might live.

They had no need of moving, Tordos Gar and many others had argued; they could stay where they were forever, and never find any need for leaving their planet. This was the voice of decadence, Taj Lamor told himself; and he had grown to hate that voice.

There were other men, men who had gone to that other solar system, men who had seen vast oceans of sparkling water, showering from their ruffled surfaces the brilliant light of a great, hot sun. They had seen towering masses of mountains that reached high into the blue sky of a natural atmosphere, their mighty flanks clothed with green growth; natural plants in abundance.

And best of all, they had fought and seen action, such as no member of their race had known in untold ages. They knew Adventure and Excitement, and they had learned things that no member of their ancient race had known for millennia. They had learned the meaning of advancement and change. They had a new ardor, a new strength, a new emotion to drive them, and those who would have held them back became enthusiasts themselves. Enthusiasm may be contagious, but the spirit of their decadence was rapidly failing before this new urge. Here was their last chance and they must take it; they would!

They had lost many men in that battle on the strange world, but their race was intelligent; they learned quickly, the small ships had been very hard targets, while their big ships were too easy to strike. They must have small ships, yet they must have large ships for cargo, and for the high speed driving apparatus. The small ships were not able to accelerate to the terrific speed needed. Once their velocity had been brought up to the desired value, it was easy to maintain it with the infinitely small friction of space as the only retarding force; one atom per cubic inch was all they must meet. This would not hold them up, but the great amount of fuel and the power equipment needed to accelerate to the desired speed could not be packed into the small ship. Into the vast holds of the huge ships the smaller ones were packed, long shining rows of little metal projectiles. Tiny they were, but they could dart and twist and turn as swiftly as could the ships they had met on that other world—tiny ships that flashed about with incredible suddenness, a target that seemed impossible to hit. These ships would be a match for those flashing motes of the Yellow Sun. Now it might be that their great transport and battle ships could settle down to those worlds and arrange them for their own people!

And they had discovered new weapons, too. One of their mightiest was a very old apparatus, one that had been forgotten for countless ages. A model of it was in existence in some forgotten museum on a deserted planet, and with it long forgotten tomes that told of its principles, and of its consequences. Invisibility was now at their command. It was an ancient weapon, but might be exceedingly effective!

And one other. They had developed a new thing! They had not learned of it in books, it was their invention! They did not doubt that there were other machines like it in their museums, but the idea was original with them. It was a beam of electrical oscillatory waves, projected with tremendous energy, and it would be absorbed by any conductor. They could melt a ship with this!

And thus that great field had been filled with Giants of Space! And in each of these thousand great warships there nestled three thousand tiny one-man ships.

Here was a sight to inspire any race!

Taj Lamor watched as the last of the working machines dragged its slow way out of the great ships. They were finished! The men were already in them, waiting to start, and now there was an enthusiasm and an activity that had not been before; now the men were anxious to get that long journey completed and to be there, in that other system!

Taj Lamor entered his little special car and shot swiftly down to the giant cruisers. He stepped out of his little craft and walked over to the tube conveyor ready for the trip to the nose of the great vessel. Behind him attendants quickly moved his car to a locked cradle berth beside long rows of similar vehicles.

A short while later those who were to remain on the dark planet saw the first of the monsters of space rise slowly from the ground and leap swiftly forward; then as methodically as though released by automatic machinery, the others leaped in swift pursuit, rushing across half a world to the tremendous space lock that would let them out into the void. In a long, swift column they rushed on. Then one at a time they passed out into the mighty sea of space. In space they quickly formed and set out.

As though by magic, far to the left of their flight, there suddenly appeared a similar flight of giant ships, and then to the right, and above them, another seemed to leap out of nothingness as the ships of other planets came into sight. Quickly they formed a vast cone about their leader's ship, a protecting screen, yet a powerful offensive formation.

Endlessly, it seemed, they sped on through the darkness. Then as the yellow star flamed brighter and brighter before them, they slowed their ships till the small fliers could safely be released into space.

Like a swarm of insects flying about giant birds of space the little ships circled the mighty masses of the battle cruisers. So huge were they, that in the combined mass of the fleet there rested sufficient gravitational attraction to force the little fliers to form orbits about them. And so they sped on through the void, the vast conical fleet with its slowly circling belt of little ships. A fleet whose counterpart had never entered the Solar System.

It was well beyond the orbit of Pluto that the first of the Solarian scouts detected the approaching invasion fleet. The tension that had gripped Earth and Venus and their guardian ships for so long a time suddenly snapped; and like a great machine set into sudden motion, or a huge boulder, balanced, given the last push that sends it spinning with destructive violence down a slope, the fleet went into action.

It was merely a little scout, a ten-man cruiser, that sent in the message of attack, and then, upon receiving headquarters' permission, went into action. Some of the tacticians had wanted to try to get the entire fleet into battle range for a surprise attack in power; but others felt that this could not possibly succeed. Most important, they decided, was the opportunity of learning if the invaders had any new weapons.

The Nigrans had no warning, for a ten-man cruiser was invisible to them, though the vast bulk of their own ships stood out plainly, lighted by a blazing sun. No need here to make the sun stand still while the battle was finished! There was no change out here in all time! The first intimation of attack that the Nigrans had was the sudden splitting and destruction of the leading ship. Then, before they could realize what was happening, thirty-five other destructive molecular motion beams were tearing through space to meet them! The little ten-man cruiser and its flight of speedsters was in action! Twenty-one great ships crumpled and burst noiselessly in the void, their gases belching out into space in a great shining halo of light as the sun's light struck it.

Unable to see their tiny enemies, who now were striking as swiftly, as desperately as possible, knowing that death was practically certain, hoping only to destroy a more equal number of the giants, they played their beams of death about them, taking care to miss their own ships as much as possible.

Another ship silently crumpled, and suddenly one cruiser right in the line of the flight was brought to a sudden halt as all its molecules were reversed. The ships behind it, unable to stop so suddenly, piled up on it in chaotic wreckage! A vast halo of shining gas spread out fifty thousand miles about, blinding further the other ships, the radiance about them making it impossible to see their tiny enemies.

Now other of the Solarian ships were coming swiftly to the attack. Suddenly a combination of three of the ten-man cruisers stopped another of the great ships instantaneously. There was another soundless crash, and the giant mass of wreckage that heaped suddenly up glowed dully red from the energy of impact.

But now the little ships of the invaders got into action. They had been delayed by the desperate attempts of the dreadnaughts to wipe out their enemies with the death rays, and they could not cover the great distances without some delay.

When a battle spreads itself out through a ten-thousand mile cube of space—through a thousand billion cubic miles of space—it is impossible to cover it instantaneously with any machine.

Already nearly a hundred and fifty of the giant liners had gone into making that colossal mass of junk in space. They must protect the remaining cruisers! And it was that flight of small ships that did protect them. Many of the Solarians went down to death under their rays. The death rays were exceedingly effective, but the heat rays were not able to get quite as long a range, and they were easily detected by the invisibility locators, which meant certain destruction, for a molecular motion ray would be there in moments, once they had been located.

The main fleet of the Solar System was already on its way, and every moment drew closer to this running battle, for the great ships of the Nigrans had, although they were entering the system cautiously, been going at a very high speed, as interplanetary speeds are measured. The entire battle had been a running encounter between the two forces. The Solarian force, invisible because of its small size, was certainly getting the better of the encounter thus far, but now that the odds were changing, now that the small ships had come into the fray, engaging them at close range, they were not having so easy time of it.

It would be many hours before the full strength of the Solarian fleet could be brought to bear on the enemy. They were not able to retire and await their arrival, for they must delay the Nigran fleet. If even one of those great ships should safely reach the two planets behind them—!

But within a half hour of the original signal, the Rocket Squad had thrown itself into the battle with a fervor and abandon that has given that famous division a name that will last forever.

The small fliers of the Nigrans were beginning to take an appalling toll in the thinning ranks of the Solarians. The coming of the Rocket Squad was welcome indeed! They were able to maneuver as swiftly as the enemy; the speedsters were harder to spot than the Solarian ten-man and thirty-man boats. The Solarian speedsters were even smaller than the comparable Nigran craft, and some of these did a tremendous amount of damage. The heat ray was quite ineffective against the ten-man ships, even when working at full capacity, when produced by the small generators of the Nigran one-man boats. The cruisers could absorb the heat and turn it into power faster than the enemy could supply it. Beams from the monster interstellar liners were another matter, of course.

But the one-man speedsters had a truly deadly plan of attack against the liners. The plan was officially frowned upon because of the great risks the pilots must take. They directed their boats at one of the monster ships, all the power units on at full drive. As close to target as possible the man jumped from his ship, clothed, of course, in an altitude suit equipped with a radio transmitter and receiver.

Death rays could not stop the speedsters, and with their momentum, the invaders could not make it less deadly with their heat beam, for, molten, it was still effective. A projectile weighing twenty-two tons, moving a hundred miles a second, can destroy anything man can lift off a planet! Their very speed made it impossible to dodge them, and usually they found their mark. As for the risk, if the Solarian forces were victorious, the pilots could be picked up later, provided too long a time had not elapsed!

In the midst of the battle, the Solarians began to wonder why the Nigran fleet was decreasing so rapidly—certainly they had not caused all that damage! Then suddenly they found the answer. One of their ships—then another—and another fell victim to a pale red ray that showed up like a ghostly pillar of luminosity coming from nowhere and going nowhere! The answer? The invaders' ships were becoming invisible! The invisibility detectors were being overloaded now, and the hunt was hard, while the Nigrans were slipping past them and silently destroying Solarian ships! The molecular motion rays were quite effective on an invisible ship—once it had been found. They were destroying the Nigrans as rapidly as they were being destroyed, but they were letting some of them slip past! The luminous paint bombs and bullets were now called into play. All enemy ships were shot at with these missiles, and invisibility was forestalled.

At long last the dark bulk of the main fleet approached, a scarcely visible cloud of tiny darting metal ships. The battle so far had been a preliminary engagement. The huge ships of the Nigrans were forced to stop their attack, and releasing the last of the fliers, to retire to a distance, protected by a screen of small ships, for they were helpless against the Solarian speedsters. Invisibility fell into disfavor, too, now that there were plenty of Solarian ships, for the Nigrans were more conspicuous when invisible than when visible. The radio detector could pick them out at once.

The entire Nigran fleet was beginning to reveal the disorder and uncertainty that arose from desperation, for they were cornered in the most undesirable position possible. They were outside the Solarian fleet, and their ships were lighted by the glare of the sun. The defenders, on the other hand, were in such a position that the enemy could see only the “night” side of them—the shadowed side—and, as there was no air to diffuse the light, they were exceedingly hard to find. In the bargain, the radium paint was making life for the Nigrans a brief and flitting thing!

The invaders began to pay an awful toll in this their first real engagement. They lacked the necessary power to cover the entire Solarian fleet with their death rays, and their heat weapons were of little help. The power of the small ships did not count for much—and the big liners could not use their weapons effectively for their small fliers must be between them and their adversary. Despite this, however, the Nigrans so greatly outnumbered the Earth-Venus forces that it looked as though a long and costly war lay ahead.

At last the Solarian generals tried a ruse, a ruse they hoped would work on these beings; but they who never before had to plan a war in space, were not sure that their opponents had not had experience in the art. True, the Nigrans hadn't revealed any especially striking generalship—had, in fact, committed some inexcusable blunders—but they couldn't be sure. Though they didn't know it, the Solarians had the advantage of thousands of years of planetary warfare to rely on. This stood them in good stead now.

The Nigrans were rallying rapidly. To their surprise, the forces of the Solarians were dwindling, and no matter how desperately this remnant fought, they could not hold back the entire force of the Nigran fliers. At last it appeared certain that the small ships could completely engage the Solarian fleet!

Quickly the giant cruisers formed a great dense cone of attack, and at a given signal, the fliers cleared a hole for them through the great disc-shaped shield of the defenders. And with all their rays fanned out in a 100% overlap ahead of them, the Nigran fleet plunged through the disc of ships at close to four hundred miles per second. They broke through—were on their way to the unprotected planets!

The Solarian ships closed the gap behind them, and eighteen of the giant ships burst into wreckage as powerful beams found them, but for the most part the remnant of the defending forces were far too busy with the fliers to attack the large ships. Now, as the monster engines of destruction raced on toward the planets still approximately two billion miles away, they knew that, far behind them, their fliers were engaging the Solarians. They had left their guard—but the guard was keeping the enemy occupied while they were free to drive in!

Then from nowhere came the counterattack! Nearly five thousand thirty-man ships of Earth and Venus, invisible in the darkness of space, suddenly leaped into action as the dreadnoughts sped past. Their destroying rays played over the nigh-helpless giants, and the huge ships were crumbling into colossal derelicts. With the last of their guard stripped from them, they fell easy prey to the attackers. Faster than they could keep count they were losing their warships of space!

The ruse had worked perfectly! Nearly all of the ten-man and one-man ships had been left behind them in the original disc, while all the thirty-man light cruisers, and a few hundred each of the ten-man and one-man crafts sped away to form a great ring twenty thousand miles farther back. The Nigran fleet had flown blindly into the ambush.

There was only one thing left for them to do. They were defeated. They must return to their far-off black star and leave the Solarians in possession of their worlds. For all battle purposes their great force was nearly wiped out, only the fliers remained in force; and these could no longer be carried in the remnant of the great liners. Swiftly they fell back, passing again through the disc, losing thirty more vessels, then raced swiftly away from the fleet of their enemies.

The Solarians, however, were not content. Their ships were forming in a giant hollow cylinder, and as the sphere of the Nigrans retreated, their beams playing behind them, the cylinder moved forward until it surrounded them, and they raced together toward the distant lightless sun. The Solar end of the cylinder swiftly closed, blocked by a group of huge ships which had taken no visible part in the battle. The Nigrans had stopped using their rays; and the Solarians followed in armed readiness, not molesting as long as they were not molested.

Many days this strange flight lasted, till at last the great yellow sun, Sol, had faded in the distance to an unusually brilliant star. Then, suddenly visible out of the darkness, a strange black world loomed ahead, and the Nigran ships settled swiftly toward it. Through the airlocks the great liners settled to their planet. No action was taken so long as the Solarian ships were not menaced, but for eight long months the darting ships hung above the four englobed worlds of Nigra.

Then at last the astronomers of Earth and Venus sent through the billions of miles of ether their message of safety. The guard could return home, for the sun they had been guarding would soon be too far from Earth or Venus to make any attack logical. Despite this, for years to come the fleet would guard the rim of the System, just to be sure; but it appeared that the suns had passed, never again to meet.

A strange thing had happened during the passing of the stars. Pluto no longer circled Sol; it had been captured by Nigra! The great fleet returned to a changed Solar system. Sol was still at its center, but there were now ten planets, including two new ones that the sun had captured from Nigra in return for Pluto; and all the planets had shifted a bit in their orbits.

What the ultimate effect on the planets will be, we cannot say as yet. The change thus far is certainly not very great, though a somewhat warmer climate exists now on Earth, and it is a bit cooler on Venus. The long-range difference, however, will be exceedingly interesting.

The Solar System has just passed through an experience which is probably unique in all the history of the mighty nebula of which our sun is an infinitesimal part. The chances that one star, surrounded by a system of planets, should pass within a hundred billion miles of another star, similarly accompanied, was one in billions of billions. That both systems should have been inhabited by intelligent races—

It is easy to understand why the scientists could not believe Arcot's theory of attack from another sun until they had actually seen those other worlds.

In that war between two solar systems we learned much and lost much. Yet, in all probability we gained more than we lost, for those two new-old planets will mean tremendous things to us. Already scientists are at work in the vast museums and ancient laboratories that are on them, and every day new things are being discovered. We lost many men, but we saved our worlds, and we learned many invaluable secrets from the invaders. In addition, we have but scratched the surface of a science that is at least a thousand million years old!

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