He sat with his chin on his chest, wearily debating the impossibility of meeting a situation in which all humanity might well be involved. His achievement of space travel provided no sense of triumph, and the discovery of the abandoned fortress produced no elation. Not when a desperate emergency requiring a non-existent garrison to report for duty was so probable. Burke sat in the control-chair and could find no encouragement in any of his thoughts....
He heard a trumpet-call and was on his feet, buckling familiar equipment about him. There were other figures all around in this bunkroom, similarly equipping themselves. Some grumbled. There was a rush for the doorway and he found himself one of a line of trotting figures which swung sharply out the door and went swiftly down one of the high-ceilinged corridors. The faces he saw were hardbitten and resentful. They moved, but out of habit, not choice. There were other lines of men in motion. Some rushed in the same direction. Others ran stolidly into branching corridors and were lost to sight. Up a ramp, with the pounding of innumerable feet filling his ears with echoed sound. Suddenly there were fewer men before him. Some had darted through a doorway to the right. More vanished. He was at the head of his line. He turned into the doorway next beyond, and saw a squat and menacing object there. He swung up its side and seated himself. He dropped a helmet over his head and saw empty space with millions of unwinking stars beyond it. He waited. He was not Burke. He was someone else who happened to be the pointer, the aimer, of the weapon he sat astride. This might be a drill, but it could be action.
A voice spoke inside his helmet. The words were utterly strange, but he understood them. He tested the give of this lever and the response of that. He spoke crisply, militarily, in words that somehow meant this—a word missing—was ready for action at its highest rate of fire.
Again he waited, his eyes examining the emptiness he saw from within his helmet. A star winked. He snatched at a lever and centered it, snapping sharp, bitten-off words. The voice in his helmet said, "Flam!" He jerked the firing-lever and all space was blotted out for seconds by flaming light. Then the light faded and far, far away among the stars something burned horribly, spouting fire. It blew up.
Yet again he waited. He doggedly watched the stars, because the Enemy had some way to prevent detection by regular instruments, and only the barest flicker of one among myriad light-specks could reveal the presence of an Enemy craft.
A long time later the voice in his helmet spoke again, and he relaxed, and lifted the helmet. He nodded to the others of the crew of this weapon. Then a trumpet blew again, and he dismounted leisurely from the saddle of the ungainly thing he'd fired, and he and his companions waited while long lines of men filed stolidly past the doorway. They were on the way back to the bunk-rooms. They did not look well-fed. His turn came. His crew filed out into the corridor, now filled with men moving in a bored but disciplined fashion. He heard somebody say that it was an Enemy scout, trying some new device to get close to the fortress. Eight weapons had fired on it at the same instant, his among them. Whatever the new device was, the Enemy had found it didn't work. But he knew that it needn't have been a real Enemy, but just a drill. Nobody knew when supposed action was real. There was much suspicion that there was no real action. There was always the possibility of real action, though. Of course. The Enemy had been the Enemy for thousands of years. A century or ten or a hundred of quietude would not mean the Enemy had given up....
Then Burke found himself staring at the quietly glowing monitor-lights of his own ship's control-board. He was himself again. He remembered opening his eyes. He'd dozed, and he'd dreamed, and now he was awake. And he knew with absolute certainty that what he'd dreamed came from the black cube he'd brought back from the previously locked-up room. But there was a difference between this dream and the one he'd had for so many years. He could not name the difference, but he knew it. This was not an emotion-packed, illusory experience which would haunt him forever. This was an experience like the most vivid of books. It was something he would remember, but he would need to think about it if he were to remember it fully.
He sat stiffly still, going over and over this new memory, until he heard someone moving about in the compartment below.
"Sandy?"
"Yes," said Sandy downstairs. "What is it?"
"I opened the door that bothered Pam," said Burke. Suddenly the implications of what had just occurred began to hit him. This was the clue he'd needed. Now he knew—many things. "I found out what the fortress is for. I suspect I know what the signals were intended to do."
Silence for a moment. Then Sandy's voice. "I'm coming right up."
In minutes she ascended the stairs.
"What is it, Joe?"
He waved his hand, with some grimness, at the small black object on the control-desk.
"I found this and some thousands of others behind that creepy door. I suspect that it accounts for the absence of signs and symbols. It contains information. I got it. You get it by dozing near one of these things. I did. I dreamed."
Sandy looked at him anxiously.
"No," he told her. "No twin moons or waving foliage. I dreamed I was a member of the garrison. I went through a training drill. I know how to operate those big machines on the second level of the corridor, now. They're weapons. I know how to use them."
Sandy's uneasiness visibly increased.
"These black cubes are—lesson-givers. They're subliminal instructors. Pam is more sensitive to such stuff than the rest of us. It didn't affect me until I dozed. Then I found myself instructed by going through an experience in the form of a dream. These cubes contain records of experiences. You have those experiences. You dream them. You learn."
Then he said abruptly, "I understand my recurrent dream now, I think. When I was eleven years old I had a cube like this. Don't ask me how it got into a Cro-Magnon cave! But I had it. One day it dropped and split into a million leaves of shiny stuff. One got away under my bed, close up under my pillow. When I slept I dreamed about a place with two moons and strange trees and—all the rest."
Sandy said, groping, "Do you mean it was magnetized in some fashion, and when you slept you were affected by it so you dreamed something—predetermined?"
"Exactly," said Burke grimly. "The predetermined thing in this particular cube is the way to operate those machines Holmes said were weapons." Then he said more grimly, "I think we're going to have to accept the idea that this cube is an instruction device to teach the garrison without their having to learn to read or write or think. They'd have only to dream."
Sandy looked from him to the small black cube.
"Then we can find out—"
"I've found it out," said Burke. "I guessed before, but now I know. There is an Enemy this fortress was built to fight. There is a war that's lasted for thousands of years. The Enemy has spaceships and strange weapons and is absolutely implacable. It has to be found. And the signals from space were calls to the garrison of this fortress to come back and fight it. But there isn't any garrison any more. We answered instead. The Enemy comes from hundreds or thousands of light-years away, and he tries desperately to smash the defenses of this fortress and others, and when he succeeds there will be massacre and atrocity and death to celebrate his victory. He's on the way now. And when he comes—" Burke's voice grew harsh. "When he comes he won't stop with trying to smash this place. The people of Earth are the Enemy's enemies, too. Because the garrison was a garrison of men!"
"I don't believe it," said Holmes flatly.
Burke shrugged. He found that he was tense all over, so he took some pains to appear wholly calm.
"It isn't reasonable!" insisted Holmes. "It doesn't make sense!"
"The question," observed Burke, "isn't whether it makes sense, but whether it's fact. According to the last word from Earth, they're still insisting that the ship's drive is against all reason. But we're here. And speaking of reason, would the average person look at this place and say blandly, 'Ah, yes! A fortress in space. To be sure!' Would they? Is this place reasonable?"
Holmes grinned.
"I'll go along with you there," he agreed. "It isn't. But you say its garrison was men. Look here! Have you seen a place before where men lived without writings in its public places? They tell me the ancient Egyptians wrote their names on the Sphinx and the Pyramids. Nowadays they're scrawled in phone booths and on benches. It's the instinct of men to autograph their surroundings. But there's not a line of written matter in this place! That's not like men!"
"Again," said Burke, "the question isn't of normality, but of fact."
"Then I'll try it," said Holmes skeptically. "How does it work?"
"I don't know. But put a cube about a yard from your head, and doze off. I think you'll have an odd dream. I did. I think the information you'll get in your dream will check with what you find around you. Some of it you won't have known before, but you'll find it's true."
"This," said Holmes, "I will have to see. Which cube do I try it with, or do I use all of them?"
"There's apparently no way to tell what any of them contains," said Burke. "I went back to the storeroom and brought a dozen of them. Take any one and put the others some distance away—maybe outside the ship. I'm going to talk to Keller. He'll make a lot of use of this discovery."
Holmes picked up a cube.
"I'll try it," he said cheerfully. "I go to sleep, perchance to dream. Right! See you later."
Burke moved toward the ship's air-lock.
"Pam and I have some housekeeping to do," Sandy said.
Burke nodded abstractedly. He left the ship and headed along the mile-long corridor with the turn at the end, a second level and another turn, and then the flight of steps to the instrument-room. As he walked, the sound of his footsteps echoed and reëchoed.
Behind him, Holmes set a cube in a suitable position and curled up on one of the side-wall bunks in the upper compartment of the spaceship.
"We'll go downstairs," said Sandy.
Pam parted her lips to speak, and did not. They disappeared down the stair to the lower room. Then Sandy came back and picked up the extra cubes.
"Joe said to move them," she explained.
She disappeared again. Holmes settled himself comfortably. He was one of those fortunate people who are able to relax at will. Actually, in his work he normally did his thinking while on his feet, moving about his yacht-building plant or else sailing one of his own boats. He simply was not a sit-down thinker. Sitting, he could doze at almost any time he pleased, and for a yachtsman it was a useful ability. He could go for days on snatched catnaps when necessary. Conversely he could catnap practically at will.
He yawned once or twice and settled down confidently. In five minutes or less ...
He wriggled down into an opening barely large enough to admit his body. The top clamped and sealed overhead. He fitted his feet into their proper stirrup-like holders and fixed his hands on the controls. There was violent acceleration and he shot away and ahead. Behind him the jagged shape of the fortress loomed. He swung his tiny ship. He drove fiercely for the tiny rings of red glow which centered themselves in the sighting-screen before him. He drove and drove, while the fortress dwindled to a dot and then vanished.
On either side of his ship a ten-foot steel globe clung. He checked them over, tense with the realization that he must very soon be within the practical timing-range of the new Enemy solid missiles. He made minute adjustments in the settings of the globes.
He released them together. They went swinging madly away at the end of a hair-thin wire which would sustain the tons of stress that centrifugal force gave the spheres. They spiraled toward darkness with its background of innumerable stars. The Enemy would be puzzled, this time! They'd developed missile-weapons with computing sights. In their last attack, five hundred years before, the Enemy had been defeated by the self-driving globes that had an utterly incredible acceleration. It was reported from the Cathor sector that in this current attack they had missile-weapons with a muzzle-velocity of hundreds of miles per second, which could actually anticipate a globe with a hundred-sixty-gravity drive. They could fire a solid shot to meet it and knock it down, because of some incredible computer-system which was able to calculate a globe's trajectory and meet it in space. They were smart, the Enemy!
The two globes went spinning toward the Enemy. Linked together, they spun round and round and no conceivable computer could calculate the path of either one so a projectile could hit. They did not travel in a straight line, as a trajectory in space should be. Whirling as they did around a common center of gravity, with the plane of their circling at a sharp angle to their line of flight, it was not possible to range them for gunfire. Their progress was in a series of curves, each at a different distance, which no mere calculator could solve without direction. A radar could not pick up the data a computer would need. One or the other globe might be hit, but it was far from likely.
The pilot of the one-man ship saw the blue-white flame of a hit. He flung his ship about and sped back toward the fortress. The Enemy would beat this trick, in time. Four thousand years before they'd almost won, when they invaded the Old Nation. They were getting bolder now. There was a time when a sound beating sent them back beyond the Coal-sack to lick their wounds for two thousand years or better. Lately they came more often. There'd been a raid in force only five hundred years back, and only fifteen before that ...
Holmes, obviously, had the odd dream Burke had prophesied. But Burke was up in the instrument-room by then. Keller gazed absorbedly at a vision-plate. It showed a section of the exterior surface of the asteroid—harsh, naked rock, with pitiless sunlight showing the grain and structure of the rock-crystals. Where there was shadow, the blackness was absolute. As Burke entered, Keller turned a knob. The image changed to a picture of a compartment inside the fortress. It was a part of the maze of rooms and galleries that none of the newcomers had visited. Panels and bus-bars and things which were plainly switches covered its walls. It was a power-distribution center. Keller turned the knob back, and the view of the outside of the asteroid returned.
Keller turned and blinked at Burke, and then said happily, "Look!"
He went to another vision-screen with an image of another part of the outer surface. He turned that knob, and the image dissolved into another. This was a gigantic room, lighted like more familiar places. In its center there was an enormous, gigantic machine. There were domes of metal, with great rods of silvery stuff reaching across emptiness between them. There were stairs by which one could climb to this part and that. Judging by the steps and the size of the light-tubes, the machine was the size of a four-storey house. And on the floor there were smaller machines, all motionless and all cryptic.
Keller said with conviction, "Power!"
Burke stared. Keller recovered the original view and went to still other plates. In succession, as he turned the knobs, Burke saw compartment after compartment. There was one quite as huge as the one containing the power-generating machine. It contained hemispheres bolted ten feet above the floor on many columns. There was a network of bus-bars, it seemed, overlying everything, and there were smaller devices on the floor below it.
"Gravity!" said Keller with conviction.
"Good enough," said Burke. "We've found something too, which may be useful with those machines. If we can—"
Keller held up his hand and went to one special screen. When he changed the image, the new one was totally unlike any of the others. This was a close-up. It showed a clumsy, strictly improvised and definitely cobbled metal case against a wall. It had been made by inept hands. It was remarkable to see such indifferent workmanship here. But the really remarkable thing was that the face of the box contained an inscription, burned into the metal as if by a torch. The symbols had no meaning to Burke, of course. But this was an inscription in a written language.
Keller rubbed his hands, beaming.
"It could be a message for somebody who'd come later," said Burke. "It's hard to think of it being anything else. But it wasn't placed for us to find. It should have been set up beside the ship-lock we were expected to come in by and did come in by."
"We'll see," said Keller zestfully. "Come on!"
Burke followed him. Keller seemed somehow to know the way. They went all the way back to the ship-lock, passed it, and then Keller dived off to the right, down an unsuspected ramp. There were galleries running in every direction here, crossing each other and opening upon an indefinite number of what must have been storerooms. Presently Keller pointed.
There was the case against the wall. It faced a wide corridor. It did not belong here. It was totally unlike any other artifact they had seen, because it seemed to have been made totally without skill. Yet there was an inscription—and the making of written records had appeared to be a skill the former occupants of the asteroid had not possessed. Keller very zestfully essayed to open it. He failed.
Burke said, "We'll have to use tools to get it open."
"Somebody made it," said Keller, "just before the garrison went away. They made it here!"
"Quite likely," agreed Burke. "We'll get at it presently. Now listen, Keller! I came along because a message might be useful. I think Holmes has found out something, though what it may be I can't guess. Come along with me. There've been developments and I want to hold a council of war. And I think I do mean war!"
He led the way back toward the ship. When they arrived, Holmes was awake and growling because of Burke's absence.
"You win," he told Burke. "I had a dream, and it wasn't a dream. I know something about those metal globes. They've got drives in them, and they can accelerate to a hundred and sixty gees, and I don't think I'll ride one."
Wryly, he told Burke what he'd experienced.
"I'm not too much surprised," said Burke. "I've managed two cube-experiences myself. I figure that these cubes trained men to operate things, without training their brains in anything else. They'd make illiterates into skilled men in a particular line, so anybody could do the work a highly trained man would otherwise be needed for. In one of my two cube-dreams I was a gun-pointer on one of those machines up on the third level. In the second cube-dream I was a rocket-pilot."
"No rockets in my cube," protested Holmes.
"Different period," said Burke. "Maybe, anyhow. In my dream we were using rockets to fight with, and the war was close. The enemy had taken some planets off Kandu—wherever that is!—and the situation was bad. We went out of here in rockets and fought all over the sky. But then there were supplies coming from home, and fresh fighting men turning up." He stopped abruptly. "How'd they come? I don't know. But I know they didn't come in spaceships. They just came, and they were new men and we veterans patronized them. The devil! Holmes, you say the globes have a hundred-sixty-gee drive! Nobody'd use rockets if drives like that were known!"
"To stay in the party," Sandy said suddenly, with something like defiance, "I tried a cube, too. And I was a sort of supply-officer. I had the experience of being responsible for supply and being short of everything and improvising this and that and the other to keep things up to fighting standard. It wasn't easy. The men grumbled, and we lacked everything. There was no fighting in my time, and there hadn't been for centuries. But we knew the Enemy hadn't given up and we had to be ready, generation after generation, even when nothing happened. And we knew that any minute the Enemy might throw something unexpected, some new weapon, at us."
"History-cubes," said Keller interestedly. "Different periods. Right?"
"Dammit, yes!" said Burke. "We've got accounts of past times and finished battles, but we need to know who's coming and what to do about it! Maybe the rocket-dream was earliest in time. But how could a race with nothing better than rockets ever get here? And how could they supply the building of a place like this?"
There was no answer. Facts ought to fit together. When they don't, they are useless.
"We've got snatches of information," said Burke. "But we don't know who built this fort, or why, except that there was a war that lasted thousands of years, with pauses for centuries between battles." He waved a hand irritably. "The Enemy tries to think up new weapons. They do. They try them. So far, they've been countered. But we're not prepared to fight a new weapon. Maybe the fort is set to battle old ones, but we don't know how to use it even for that! We've got to—"
"I think—" began Keller.
"I'd give plenty for a service manual on the probably useless weapons we do have," said Burke angrily. "Incidentally, Keller just found what may be an explanation of how and why this place was abandoned."
Keller said suddenly, "Where would service manuals be?"
He moved, almost running, toward the air-lock. Burke started to swear, and stopped.
"A service-and-repair manual," he snapped, "would be near the equipment it described. How many little shelves with boxes on them have we seen? They're just the right size to hold cubes! And where are they? Next to those fighting machines next to the door of the room where the ten-foot globes are! There's a shelf of them in the instrument-room! Let's find out how to fight with this misbegotten shell of a space-fort! There'll be no help coming to us, but if the Enemy's held off for thousands of years while this civilization fell apart, we might as well try to hold it together for a few minutes or seconds longer! Let's go get some real instruction-cubes!"
Keller was already gone. The others followed. Once they saw Keller in the far, far distance, hastening toward the instrument-room. Behind him, after almost running down the long corridor, Burke swung into the room where hundreds of ten-foot metal globes waited for the fortress to be remanned and to go into action again. Inside the door he found the remembered shelf, with two small boxes fastened to it. He pulled down one box and opened it. There was a black cube inside it. He thrust it upon Holmes.
"Here!" he said feverishly. "Find out how those globes work! Find out what's in them, how they drive!"
He ran. To the end of the corridor and up the ramp and past the supposed bunk-rooms and mess-halls. Up to the level where the ugly metal machines stood, each in its separate cubicle. There were little shelves inside each door. Each shelf contained a single box. Burke took one, two, and then stopped short.
"They'll be practically alike," he muttered. "No need."
He put one back. And then he felt almost insanely angry. One would need at least to be able to doze, to make use of the detailed, vivid, and utterly convincing material contained in the black cubes. And how could any man doze or sleep for the purpose of learning such desperately needed data? He'd need almost not to want the information to be able to sleep to get it!
Sandy and Pam overtook him as he stood in harried frustration with a black cube in his hands.
"Listen to me, Joe," said Sandy. "We've all taken chances, but if you get recurrent dreams from every cube you doze near—"
"When that happened to me," snapped Burke, "I was eleven years old and had one moment only. And that dream wasn't affected by the others in the cubes that came after it. And anyhow, no matter what happens to Holmes and me, we have to get these things ready for use! I don't know what we'll use them against. I don't know whether they'll be any use at all. But I've got to try to use them, so I've got to try to find out how!"
Sandy opened her mouth to speak again.
"I'm going off to fret myself to sleep," added Burke. "Holmes will be trying it too. And Keller."
"I don't think it's necessary," said Sandy.
"Why?"
"You found a sort of library of cubes. How useful would they be if one had to doze off to read them? How handy would a manual about repairing a weapon be, if somebody had to take a nap to get instructions? It wouldn't make sense!"
"Go on!" said Burke impatiently.
"Why not look in the library?" asked Sandy. "As a quartermaster officer, IthinkI knew that there was a reading-device for the cubes, like a projector for microfilm. It might have been taken away, but also—"
"Come along!" snapped Burke. "If that's so, it's everything! And it ought to be so!"
They hastened to the vast, low-ceilinged room which was filled with racks of black cubes. They were stacked in their places. At the far corner they found a desk and a cabinet. In the cabinet they found two objects like metal skull-caps, with clamps atop them. A cube would fit between the clamps. Burke feverishly sat a cube in position and put the skull-cap on his head. His expression was strange. After an instant he took it off and reversed the cube. He put it on. His face cleared. He lifted it off.
"I had it on backwards the first time," he said curtly. "This is better than dreaming the stuff. This lets you examine things in detail. You know you're receiving something. You don't think you're actually experiencing. We'll get this other reading-machine to Keller, so he can understand the equipment in the instrument-room. Holmes will have to wait."
Sandy said, "I can use him. Doesn't it occur to you, Joe, that we've only partly explored the top half of the fortress? We've only looked at what's between us and the instrument-room. There are all the stores—there were stores! And the generators down below. I can lead the way there now!"
"What do you know about the weapons?" demanded Burke.
"Nothing," said Sandy. "But I know something about the morale of the garrison. When grumbling began, discipline tightened up. And that worked for the men, but the women—"
"Women!" said Pam incredulously.
"They were an experiment," Sandy told her, "to see if they would content men on duty in an outpost. It'd been going on for only a few hundred years. It didn't seem to work too well. They wanted supplies that weren't exactly military, and at the time the cube I used was made, there was trouble getting even military things!"
Burke said impatiently, "I'll get one of these things to Keller. That's the most important thing. Tell Holmes not to try to sleep. Take him down to look over the supplies, if there are any. I'd guess that the garrison took most of them along. I doubt there's much left that we could use."
He made his way out of the cube-library and vanished.
Pam said uncomfortably, "Joe dreamed about a woman and is no good to you, in consequence. If there were women in this garrison, using the cubes might make anybody—"
Sandy tensed her lips.
"I don't think Joe is thinking about his old dream. Something deadly's on the way here. His mind's on that. I suspect all three of the men are concentrating on it. They're in no mood for romance."
"Don't you think I've noticed?" Pam said gloomily. "But I'm coming with you when you show him the storerooms!"
The "him" was obviously Holmes, whose attention had been so much taken up by the problems the fortress presented that Pam felt pushed much farther on the side lines than she liked. It was one thing to be present to watch and help and cheer on a man who planned to do something remarkable. But it was less satisfying when he became so absorbed that he didn't notice being watched, and couldn't be helped, and didn't need to be cheered on. Pam was disgruntled.
Then, for a considerable number of hours, absurdly trivial activities seemed to occupy all the people in the asteroid. Burke and Keller sat in the thirty by thirty-foot instrument-room, each wearing a small metal half-cap with a black cube held atop it between a pair of clamps. Their expressions were absorbed and intent, while they seemed attired for a children's halloween party. Now and again one of them exchanged one cube for another. About them there was a multiplicity of television screens, each screen presenting a picture of infinitely perfect quality. Every square foot of the outside of the asteroid could be seen on one or another of the screens. Then, besides, there were banks of screens which showed every square degree of the sky, with every star of every magnitude represented so that one could use a magnifying glass upon the screen to discover finer detail.
Once, during the hours when Burke and Keller were sitting quite still, Keller reached over and threw a switch. Nothing happened. Everything went on exactly as it had done before. He shook his head. And much later he went to one of the star-image screens. He moved an inconspicuous knob in a special fashion, and the star-image expanded and expanded until what had been a second of arc or less filled all the screen's surface. The effect of an incredibly powerful telescope was obtained by the movement of one control. Keller restored the knob to its original place and the image returned to its former scale. These were the only actions which took place in the instrument-room.
In the lower part of the asteroid, not much more occurred. The entrance to the power and storage areas was not hidden. It simply had not been entered. Sandy and Holmes and Pam went gingerly down a corridor with doors on either side, and then down a ramp, and then into huge caverns filled with monstrous metal things. There was no sign of any motion anywhere, but gigantic power-leads led from the machines to massive switchboards, whose switches were thrown by relays operated from somewhere else.
Then there were other caverns which must have contained many varieties of stores. There were great cases, broken open and emptied. There were bins with only dust at their bottoms. There were shelves containing things which might have been textiles, but which crumbled at a touch. Some thousands of years in an absolute vacuum would have evaporated any substance giving any degree of flexibility. These objects were useless. There was a great room with a singular hundred-foot-high machine in it, but there was no vibration or sound to indicate that it was in operation. This, Sandy said decisively, was the artificial-gravity generator. She did not know how it worked. It would have been indiscreet to experiment.
She led the way through relatively small corridors to areas in which there were very many small compartments. These had been for foodstuffs. But they were empty. They had been emptied when the asteroid was abandoned.
Then they came to the crudely fashioned case with the cryptic symbols on its front.
"This is the thing Joe mentioned," said Sandy. "They had writing. They'd have to, to be civilized. But this is the only writing we've seen. Why'd they write it?"
"To tell somebody something they'd miss, otherwise," Pam said.
"Who'd come down here? Why not put it at the ship-lock where people could be expected to come?"
Holmes grunted. "Asking questions like that gets nowhere. It's like asking how the garrison was supplied. There's no answer. Or how it left."
Sandy said in a surprised voice, as if saying something she hadn't realized she knew. "There were service ships. They serviced the television eyes on the outside, and they drilled at launching missiles, and so on. They were modified fighting ships, made over after ships didn't fight any more."
She hesitated, then went on.
"It's odd that I didn't think of telling Joe this! Some of the food supply came from Earth at the time my cube was made. As a quartermaster officer, I was authorized to allow hunting on Earth in case of need. So the serviceships went to Earth and came back with mammoths tied to the outside of their hulls. They had to be re-hydrated, though. Frozen though they were, they dried out in the long trip through vacuum from Earth."
Then she shivered a little.
Pam looked at her strangely. Holmes raised his eyebrows. He'd had one experience of training-cubes. Sandy'd had quite another. Holmes felt that instinctive slight resentment a man feels when he lacks a position of authority in the presence of a woman.
"In my time—in the cube's time—there was even a hunting camp on Earth. Otherwise there simply wouldn't be enough to eat! Women were clamoring to be sent to Earth to help with the food supply. To be sent to hunt for food was a reward for exemplary service."
"Which is interesting," observed Holmes, "but irrelevant. How was the asteroid normally supplied? How did the garrison leave? Where did it come from? Where did it go? Maybe the answer's in this box. If it is," he added, "it'll be in the same language as the inscription, and we can't read it."
Archaeologists on Earth would have been enraptured by any part of the fortress, but anything which promised to explain as much as Holmes had guessed the case could, would be a treasure past any price.
But the five people in the asteroid had much more immediate and much more urgent problems to think of. They went on a little farther and came to a storeroom which had been filled with something, but now held only the remains of packing-cases. They looked ready to crumble if touched.
"There used to be weapons stored here," Sandy said. "Hand-weapons. Not for the defense of the fortress, but for the—discipline police. For the men who kept the others obedient to orders."
"I'd be glad to have one operating pea-shooter," said Holmes.
Pam wrinkled her nose suddenly. She'd noticed something.
"I think—" she began, "I think—"
Holmes kicked at a shape which once was probably a case of wood or something similar. It collapsed into impalpable dust. It had dried out to absolute desiccation. It was stripped of every molecule which could be extracted by a total vacuum in thousands of years. It was brittle past imagining.
The collapse did not end with the object kicked. It spread. One case bulged as the support of another failed. The bulged case disintegrated. Its particles pressed on another. The dissolution spread fanwise until nothing remained but a carpeting of infinitely fine brown stuff. In one place, however, solid objects remained under the covering.
Holmes waded through the powder to the solid things. He brought them up. A case of hand-weapons had collapsed, but the weapons themselves kept their shape. They had transparent plastic barrels with curiously formed metal parts inside them.
"These might be looked into," said Holmes.
He stuffed his pockets. The hand-weapons had barrels and handgrips and triggers. They were made to shoot, somehow.
"I think—" began Pam again.
"Don't," growled Holmes. "Maybe Sandy remembers when this place was different, but I've had enough of it as it is. Let's go back to the ship and some fresh air."
"But that's what—"
Holmes turned away. Like the rest, he'd accepted great age, mentally, as a part of the nature of the fortress. But the collapse of emptied shipping-cases because they were touched was a shock. Where such decay existed, one could not hope to find anything useful for a modern emergency. He vanished.
Pam was indignant. She turned to Sandy.
"I wanted to say that I smelled fresh air," she protested. "And he acts like that!"
Sandy was not listening. She frowned.
"He could lose his way down here," she said shortly. "We'd better keep him in sight. I remember the way from my dream."
They followed Holmes, who did make his way back to the upper levels and ultimately to the ship without guidance. But Pam was intensely indignant.
"We could have gotten lost down there!" she said angrily when they were back in familiar territory. "And he wouldn't have cared! And I did smell fresh air! Not very fresh, but fresher than the aged and dried-out stuff we're breathing now!"
"You couldn't," said Sandy practically. "There simply couldn't be any, except in the ship where the hydroponic wall-gardens keep it fresh."
"But I did!" insisted Pam.
Sandy shrugged. They went into the ship, which Holmes had already reached and where he sat gloomily beside a black cube. He would have to sleep to get anything from it. There were only two of the freakish-seeming metal caps which made the cubes intelligible to a man awake, and Burke and Keller were using them. Holmes felt offended.
Sandy looked at a clock and began to prepare a meal. Pam, brooding, helped her.
Burke and Keller came back to the ship together. Keller looked pale. Burke seemed utterly grim.
"There's some stuff to be coded and sent back to Earth," he told Sandy. "Keller's got it written out. We know how to work the instruments up above, now. My brain's reeling a little, but I think I'll stay sane. Keller takes it in stride. And we know the trick the Enemy has."
Sandy put out plates for five.
"What is it?"
"Gravity," said Burke, evenly. "Artificial gravity. We don't know how to make it, but the people who built this fortress did, and the Enemy does. So they've made artificial-gravity fields to give their ships the seeming mass of suns, and they've set them in close orbits around each other. They'll come spinning into this solar system. What will happen when objects with the mass of suns—artificial or otherwise—come riding through between our sun and its planets? There'll be tidal stresses to crack the planets and let out their internal fires. There'll be no stability left in the sun. Maybe it'll be a low-grade nova when they've gone, surrounded by trash that once was worlds. Anyhow there'll be no humans left! And then the Enemy will go driving on toward the other solar systems that the builders of this fortress own. They can't conquer anything with a weapon like that, but they can surely destroy!"
Keller nodded distressedly. He gave Pam a number of sheets of paper, filled with his neat handwriting.
He said sorrowfully, "For Earth. In code."
Sandy served the meal she had prepared.
"It's a matter of days," said Burke curtly. "Not weeks. Just days."
He picked up a fork and began his meal.
"So," he said after a moment, with a sort of unnatural calm, "we've got to get the thing licked fast. Up in the instrument-room there are some theory-cubes—lectures on theories with which the operators of the room were probably required to be familiar. They were intended to figure out what the Enemy might come up with, so it could at least be reported before the fortress was destroyed. The trick of sun-gravity fields was suggested as possible, but it seemed preposterously difficult. Apparently, it was. It took the Enemy some thousands of years to get it. But they've got it, all right!"
"How do you know?" demanded Holmes.
"The disk with the red sparks in it," said Burke, "is a detector of gravity-fields. It sees by gravity, which is not radiation. Keller's sending instructions back to Earth telling how to make such detectors."
He busied himself with his food once more. After a moment he spoke again.
"We're going to try to get some help," he observed. "At least we'll try to find out if there's any help to be had. I think there's a chance. There was a civilization which built this fortress. Something happened to it. Perhaps it simply collapsed, like Rome and Greece and Egypt and Babylonia back on Earth. But on Earth when an old civilization died a new, young one rose in its place. If the one that built this fort collapsed, maybe a new one has risen in its stead. If so, it will need to defend itself against the Enemy just like the old culture did. It might prefer to do its fighting here, instead of in its own land. I think we may be able to contact it."
"How'll you look for them?"
Burke shrugged.
"I've some faint hope of a few directions in that sealed-up metal case with the inscription on it. I'm going to take some tools and break into it. It's a gamble, but there's nothing to lose."
He ate briskly, with a good appetite. Sandy was very silent.
Pam said abruptly, "We saw that case. And I smelled fresh air there. Not pure air like here in the ship, but not dead air like the air everywhere else."
"Near a power generator, Pam, there'd be some ozone," Holmes said patiently. "It makes a lot of difference."
"It wasn't ozone," said Pam firmly. "It was fresh air. Not canned air. Fresh!"
Holmes looked at Burke.
"Did you or Keller find out how the air's refreshed here? Did anybody throw a switch for air apparatus?"
Keller said mildly, "Apparatus, no. Air exchange, yes. I threw switches also for communication with base. Also emergency communication. Also dire emergency. Nothing happened."
"You see, Pam?" said Holmes. "It was ozone that made the air smell fresh."
Sandy was wholly silent until the meal was over. Then Holmes went moodily off with Keller, to use the cube-reading devices in the instrument-room and try to find, against all apparent probability, some clue or some communication which would enable something useful to be done. Holmes was trying hard to believe that things were not as bad as Burke announced, and not nearly so desperate that they had to try to find the descendants of a long-vanished civilization for a chance to offer resistance to the Enemy.
Keller said confidentially, just before they reached the instrument-room, "Burke's an optimist."
And at that moment, back in the little plastic spaceship, Burke was saying to Sandy, "You can come along if you like. There are a couple of things to be looked into. And if you want to come, Pam—"
But Pam touched the papers Keller had given her and said reservedly, "I'll code and send this stuff. Go ahead, Sandy."
Sandy rose. She followed Burke out of the ship. She was acutely aware that this was the first time since they had entered the ship that she and Burke could speak to each other when nobody could overhear. They'd spoken twice when the others were presumably asleep. But this was the first time they'd been alone.
When they'd passed through the door with the rounded corners, they were completely isolated. Overhead, brilliant light-tubes reached a full mile down the gallery in one direction, and half as far in the other. The vast corridor contained nothing to make a sound but themselves.
"It's this way," said Burke.
Sandy knew the way as well as he did, or better, but she accepted his direction. Their footsteps echoed and reëchoed, so that they were accompanied by countless reflections of heel-clicks along with the normal rustling and whispering sounds of walking.
They went a full quarter-mile from the ship-lock door, and came to a very large arched opening which gave entrance to a corridor slanting downward.
"Supplies came up this ramp," said Sandy.
It was a statement which should have been startling, but Burke nodded.
Sandy went on, carefully, "That cube about a supply-officer's duties was pretty explicit. Things were getting difficult."
Burke did not seem to hear. They went on and on. They came to the place where Keller had turned aside. Burke silently indicated the turning. They moved along this other gallery.
"Joe," said Sandy pleadingly. "Is it really so bad?"
"Strictly speaking, I don't see a chance. But that's just the way it looks now. There must be something that can be done. The trick is to find it. Meantime, why panic?"
"You—act queer," protested Sandy.
"I feel queer," he said. "I know various ways to approach problems. None of them apply to this one. You see, it isn't really our problem. We're innocent bystanders, without information about the situation that apparently will kill us and everybody back on Earth. If we knew more about the situation, we might find some part of it that could be tackled, changed. There may be something in this case—perhaps a message left by the garrison for the people who sent them here. I can't see why it'd be placed here, though."
He slowed, looking down one cross-gallery after another.
"Here it is."
They'd come to the clumsily-made case with the inscription on it. It was placed against the wall of a corridor, facing the length of another gallery which came from the side at this point. A little distance down the other passage, the line of doors was broken by an archway which gave upon a hewed-out compartment. The opening was wide enough to show a fragment of a metal floor. There was no sign of any contents. Other compartments nearby were empty. The placing of the inscribed box was inexplicable. But the inscription was sharply clear.
"Maybe," suggested Sandy forlornly, "it says something like 'Explosives! Danger!'"
"Not likely," said Burke.
He'd examined the box before. He'd brought along a tool suited to the job of opening it. He set to work, then stopped.
"Sandy," he said abruptly, "I think the gravity-generator's a couple of corridors in that direction. Will you look and see if there are any tools there that might be better than this? Just look for a place where tools might be stored. If you find something, call me."
She went obediently down the lighted, excavated corridor. She reached the vast cavern. Here there were myriad tube-lights glowing in the ceiling—and the gravity machine. It was gigantic. It was six storeys high and completely mysterious.
She looked with careful intentness for a place where tools might have been kept by the machine's attendants.
She saw movement out of the corner of her eye, but when she turned there was nothing. There could be no movement in the fortress unless by machinery or one of the five humans who'd come so recently. The asteroid had been airless for ten thousand years. It was unthinkable that anything alive, even a microbe, could have survived. So Sandy did not think of a living thing as having made the movement. But movement there had been.
She stared. There were totally motionless machines all about. None of them showed any sign of stirring. Sandy swallowed the ache in her throat and it returned instantly. She moved, to look where the movement had been. She glanced at each machine in turn. One might have made some automatic adjustment. She'd tell Burke.
She passed a fifteen-foot-high assembly of insulators and bright metal, connected overhead to other cryptic things by heavy silvery bars. She passed a cylinder with dials in its sides.
She saw movement again. In a different place. She spun around to look.
Something half the height of a man, with bird-legs and feet and swollen plumage and a head with an oversized beak which was pure caricature—something alive and frightened fled from her. It waddled in ridiculous, panicky haste. It flapped useless stumps of wings. It fled in terrified silence. It vanished.
The first thing that occurred to Sandy was that Burke wouldn't believe her if she told him.
Burke found her, rooted to the spot. He had a small metal box in his hand. He didn't notice her pallor nor that she trembled.
"I may have something," he said with careful calm. "The case had this in it. There's a black cube in the box. The case seems to have been made to hold and call attention to this cube. I'll take it up to the instrument-room and use a reader on it."
He led the way. Sandy followed, her throat dry. She knew, of course, that he was under almost intolerable emotional strain. He'd brought her along to be with her for a few moments, but he was so tense that he could think of nothing personal to say. Now it was not possible for him to talk of anything at all.
Yet Sandy realized that even under the stress that pressed upon him, he'd asked her to go look for tools in the gravity-machine room because she'd spoken of possible danger in the opening of the case. He'd gotten her away while he opened it.
When they reached the ship-lock he said briefly, "I want to hurry, Sandy. Wait for me in the ship?"
She nodded, and went to the small spacecraft which had brought them all from Earth.
When she saw Pam, inside, she said shakily, "Is—anybody else here?"
"No," said Pam. "Why?"
Sandy sat down and shivered.
"I think," she said through chattering teeth, "I think I'm going to have hysterics. L-listen, Pam! I—I saw something alive! It was like a bird this high and big as a—There aren't any birds like that! There can't be anything alive here but us! But I saw it! And it saw me and ran away!"
Pam stared and asked questions, at first soothing ones. But presently she was saying indignantly, "I do believe it! That's near the place where I smelled fresh air!"
Of course, fresh air in the asteroid, two hundred and seventy million miles from Earth, was as impossible as what Sandy had seen.
Holmes came in presently, depressed and tired. He'd been filling his mind with the contents of black cubes. He knew how cooking was done in the kitchens of the fortress, some eons since. He knew how to prepare for inspection of the asteroid by a high-ranking officer. He was fully conversant with the bugle-calls once used in the fortress in the place of a public-address loud-speaker system. But he'd found no hint of how the fortress received its supplies, nor how the air was freshened, nor how reinforcements of men used to reach the asteroid. He was discouraged and vexed and weary.
"Sandy," said Pam challengingly, "saw a live bird, bigger than a goose, in the gravity-machine room."
Holmes shrugged.
"Keller's fidgeting," he observed, "because he thinks he's seen movements in the vision-plates that show different inside views of this thing. But he isn't sure that he's seen anything move. Maybe we're all going out of our minds."
"Then Joe's closest," said Pam darkly. "He worries about Sandy!"
"And very reasonably," said Holmes tiredly. "Pam, this business of figuring that there's something deadly on the way and nothing to do about it—it's got me down!"
He slumped in a chair. Pam frowned at him. Sandy sat perfectly still, her hands clenched.
Burke came back twenty minutes later. His expression was studiedly calm.
"I've found out where the garrison went," he said matter-of-factly. "I'm afraid we can't get any help from them. Or anybody else."
Sandy looked at him mutely. He was completely self-controlled, and he did not look like a man resolutely refusing to despair, but Sandy knew him. To her it seemed that his eyes had sunk a little in his head.
"Apparently there's nobody left on the world the garrison came from," said Burke in the tone of someone saying perfectly commonplace things, "so they didn't go back there and there's no use in our trying to make a contact with that world. This was an outpost fortress, you know. It was reached from somewhere far away, and carved out and armed to fight an enemy that didn't attack it for itself, but to get at the world or worlds that made it."
He continued with immoderate calm, "I believe the home world of that civilization has two moons in its sky and something off at the horizon that looks like a hill, but isn't."
"But—"
"The garrison left," explained Burke, "because it was abandoned. It was left behind to stand off the Enemy, and the civilization it belonged to moved away. It was left without supplies, without equipment, without hope. It was left behind even without training to face abandonment, because its members had been trained by black cubes and only knew how to do their own highly special jobs by rote. They were just ordinary soldiers, like the Roman detachments left behind when the legions marched south from Hadrian's Wall and sailed for Gaul. So when there was nothing left for them to do but leave their post or starve—because they couldn't follow the civilization that had abandoned them—they left. The cube in the box was a message they set up for their former rulers and fellow-citizens if they ever returned. It's not a pretty message!"
Sandy swallowed.
"Where'd they go? What happened to them?"
"They went to Earth," said Burke tonelessly. "By twos and fives and dozens, in the service ships that came out with meat, and took back passengers. The service ships had been assigned to bring out what meat the hunting-parties could kill. They took back men who were fighters and ready to face mammoths or sabre tooth tigers or anything else. Just the same, they left a transmitter to call them back if the Enemy ever came again. But it didn't come in their lifetimes, and their descendants forgot. But the transmitter remembered. It called to them. And—we were the ones to answer!"
Sandy hesitated a moment.
"But if the garrison went to Earth," she said dubiously, "what became of them? There aren't any traces—"
"We're traces," said Burke. "They were our ancestors of ten or twenty thousand years ago. They couldn't build a civilization. They were fighting men! Could the Romans left behind at Hadrian's Wall keep up the culture of Rome? Of course not! The garrison went to Earth and turned savage, and their children's children's children built up a new civilization. And for here and for now, we're it. We've got to face the Enemy and drive him back."
He stopped, and said in a tone that was almost completely steady and held no hint of despair, "It's going to be quite a job. But it's an emergency. We've got to manage it somehow."
There was also an emergency on Earth, not simplified as in space by having somebody like Burke accept the burden of meeting it. The emergency stemmed from the fact that despite the best efforts of the air arm of the United States, Burke and the others had gotten out to space. They'd reached the asteroid M-387. Naturally. The United States thereupon took credit for this most creditable achievement. Inevitably. And it was instantly and frantically denounced for suspected space-imperialism, space-monopoly, and intended space-exploitation.
But when Keller's painstaking instructions for the building of gravity-field detectors reached Earth, these suspicions seemed less plausible. The United States passed on the instructions. The basic principle was so new that nobody could claim it, but it was so simple that many men felt a wholesome shame that they had not thought of it before. Nobody could question a natural law which was so obvious once it was stated. And the building of the device required next to no time at all.
Within days then, where the asteroid had a single ten-foot instrument, the United States had a ten-foot, a thirty-foot and a sixty-foot gravity-field detector available to qualified researchers. The new instruments gave data such as no astronomer had ever hoped for before. The thirty-foot disk, tuned for short range, pictured every gravitational field in the solar system. A previously unguessed-at Saturnian moon, hidden in the outer ring, turned up. All the asteroids could be located at one instant. The mystery of the inadequate mass of Pluto was solved within hours of turning on the thirty-foot device.
When the sixty-foot instrument went on, scaled to take in half a hundred light-years of space, the solar system was a dot on it. But four dark stars, one with planets, and twenty-odd planetary systems were mapped within a day. On that same day, though, a query went back to Keller. What, said the query, was the meaning of certain crawling, bright-red specks in mathematically exact relationship to each other, which were visibly in motion and much closer to Earth than Alpha Centaurus? Alpha Centaurus had always been considered the closest of all stars to Earth. Under magnification the bright-red sparks wove and interwove their paths as if about a common center of gravity. If such a thing were not impossible, it would be guessed that they were suns so close together as to revolve about one another within hours. Even more preposterously, they moved through space at a rate which was a multiple of the speed of light. Thirty light-speeds, of course, could not be. And the direction of their motion seemed to be directly toward the glowings which represented the solar system containing Earth. All this was plainly absurd. But what was the cause of this erroneous report from the new device?
Keller wrote out very neatly, "The instrument here shows the same phenomenon. Its appearance much farther away triggered the transmitter here to send the first signals to Earth. Data suggests red dots represent artificial gravity-fields strong enough to warp space and produce new spatial constants including higher speed for light, hence possible higher speed for spacecraft carrying artificial gravity generators. Request evaluation this possibility."
Pam coded it and sent it to Earth. And presently, on Earth, astronomers looked at each other helplessly. Because Keller had stated the only possible explanation. Objects like real suns, if so close together, would tear each other to bits and fuse in flaming novas. Moreover, the pattern of motion of the red-spark-producing objects could not have come into being of itself. It was artificial. There was a group of Things in motion toward Earth's solar system. They would arrive within so many days. They were millions of miles apart, but their gravity-fields were so strong that they orbited each other within hours. If they had gravity-fields, they had mass, which could be as artificial as their gravity. And, whirling about each other in the maddest of dances, ten suns passing through the human solar system could leave nothing but debris behind them.
Oddly enough, the ships that made those gravity-fields might be so small as to be beyond the power of a telescope to detect at a few thousand miles. The destruction of all the solar planets and the sun itself might be accomplished by motes. They would not need to use power for destruction. Gravitation is not expended any more than magnetism, when something is attracted by it. The artificial gravity-fields would only need to be built up. They had been. Once created, they could exist forever without need for added power, just as the sun and planets do not expend power for their mutual attraction, and as the Earth parts with no energy to keep its moon a captive.
The newspapers did not publish this news. But, very quietly, every civilized government on Earth got instructions for the making of a gravity-field detector. Most had them built. And then for the first time in human history there was an actual and desperately honest attempt to poll all human knowledge and all human resources for a common human end. For once, no eminent figure assumed the undignified pose involved in standing on one's dignity. For once, the public remained unworried and undisturbed while the heads of states aged visibly.
Naturally some of the people in the secret frantically demanded that the five in the fortress solve the problem all the science of Earth could not even attack. Incredible lists of required information items went out to Burke and Keller and Holmes. Keller read the lists calmly and tried to answer the questions that seemed to make sense. Holmes doggedly spent all his time experiencing cubes in the hope that by sheer accident he might come upon something useful. Pam, scowling, coded and decoded without pause. And Sandy looked anxiously at Burke.
"I'm going to ask you to do something for me," she said. "When we went down to the Lower Levels, I thought I saw something moving. Something alive."
"Nerves," said Burke. "There couldn't be anything alive in this place. Not after so many years without air."
"I know," acknowledged Sandy. "I know it's ridiculous. But Pam's felt creepy, too, as if there were something deadly somewhere in the rooms we've never been in."
Burke moved his head impatiently. "Well?"
"Holmes found some hand-weapons," said Sandy. "They don't work, of course. Will you fix one for Pam and one for me so that they do?" She paused and added, "Of course it doesn't matter whether we're frightened or not, considering. It doesn't even matter whether there is something alive. It doesn't matter if we're killed. But it would be pleasant not to feel defenseless."
Burke shrugged. "I'll fix them."
She put three of the transparent-barreled weapons before him and said, "I'm going up to the instrument-room and help Pam with her coding."
She went out. Burke took the three hand-weapons and looked at them without interest. But in a technician of any sort there is always some response to a technical problem. A trivial thing like a hand-weapon out of order could hold Burke's attention simply because it did not refer to the coming disaster.
He loosened the hand-grip plates and looked at the completely simple devices inside the weapons. There was a tiny battery, of course. In thousands of years its electrolyte had evaporated. Burke replaced it from the water stores of the ship. He did the same to the other two weapons. Then, curious, he stepped out of the ship's air-lock and aimed at the ship-lock wall. He pressed the trigger. There was a snapping sound and a fragment of rock fell. He tried the others. They fired something. It was not a bullet. The barrels of the weapons, on inspection, were not hollow. They were solid. The weapons fired a thrust, a push, an immaterial blow which was concentrated on a tiny spot. They punched, with nothing solid to do the punching.
"Probably punch a hole right through a man," said Burke, reflectively.
He took the three weapons and went toward the instrument-room. On the way, his mind went automatically back to the coming destruction. It was completely arbitrary. The Enemy had no reason to destroy the human race in this solar system. Men, here, had lost all recollection of their origin and assuredly all memory of enmities known before memory began. If any tradition remained of the fortress, even, it would be hidden in tales of a Golden Age before Pandora was, or of an Age of Innocence when all things came without effort. Those stories were changed out of all semblance to their foundations, of course, as ever-more-ignorant and ever-more-unsophisticated generations retold them. Perhaps the Golden Age was a garbled memory of a time when machines performed tasks for men—before the machines wore out and could not be replaced without other machines to make them. Perhaps the slow development of tools, with which men did things that machines formerly did for them, blurred the accounts of times when men did not need to use tools. Even the everywhere-present traditions of a long, long journey in a boat—the flood legends—might be the last trace of grand-sires' yarns about a journey to Earth. It would have been modified by successive generations who could not imagine a journey through emptiness, and therefore devised a flood as a more scientific and reasonable explanation for myths plainly overlaid with fantasy and superstition.
Burke went into the instrument-room as Sandy was asking, "But how did they? We haven't found any ship-lock except the one we came in by! And if a ship can't travel faster than light without wrapping artificial mass about itself ..."
Holmes had taken off his helmet He said doggedly, "There's nothing about ships in the cubes. Anyhow, the nearest other sun is four light-years away. Nobody'd try to carry all the food a whole colony would need from as far away as that! If they'd used ships for supply, there'd have been hydroponic gardens all over the place to ease the load the ships had to carry! There was some other way to get stuff here!"
"Whatever it was, it didn't bring meat from Earth. That was hauled out, fastened to the outside of service-boats."
"Another thing," Holmes said. "There were thousands of people in the garrison, here. How did the air get renewed? Nobody's found any mention of air-purifying apparatus in the cubes. There's been no sign of any! An emergency air-supply, yes. It was let loose when we came into the ship-lock. But there's no regular provision for purifying the air and putting oxygen into it and breaking down the CO2!"
"Won't anyone believe I smelled fresh air yesterday?" Pam asked plaintively.
No one commented. It could not be believed. Burke handed Sandy one of the weapons. He gave Pam a second.
"They work very much like the ship-drive, which was developed from them. A battery in the handle energizes them so they use the heat they contain to make a lethal punch without a kick-back. They'll get pretty cold after a dozen or so shots."
He sat down and Holmes went on almost angrily, "The garrison had to get food here. It didn't come in ships. They had to purify the air. They've nothing to do it with! How did they manage?"
Keller smiled faintly. He pointed to a control on the wall.
"If that worked, we could ask. It is supposed to be communication with base. It is turned on. Nothing happens."
"Do you know what I'm thinking?" demanded Holmes. "I'm thinking of a matter-transmitter! It's been pointed out before that we'll never reach the stars in spaceships limited to one light-speed. What good would be voyages that lasted ten, twenty, or fifty years each way? But if there could be matter-transmitters—"
Keller said gently, "Transmitters, no. Transposers, yes."
It was a familiar enough distinction. To break down an object into electric charges and reconstitute it at some distant place would be a self-defeating operation. It could have no actual value. To transmit a hundred and fifty pounds of electric energy—the weight of a man converted into current—would require the mightiest of bus-bars for a conductor, and months of time if it was not to burn out from overload. The actual transmission of mass as electric energy would be absurd. But if an object could simply be transposed from one place to another; if it could be translated from place to place; if it could undergo substitution of surroundings.... That would be a different matter! Transposition would be instantaneous. Translation would require no time. Substitution of position—a man who was here this instant would be there the next—would have no temporal aspect. Such a development would make anything possible. A ship might undertake a voyage to last a century. If a matter-transposer were a part of it, it could be supplied with fuel and air and foodstuffs on its voyage. Its crew could be relieved and exchanged whenever it was desired. And when it made a planet-fall a hundred years and more from home, why, home would still be just around the transposer. With matter-transposition an interstellar civilization could arise and thrive, even though limited to the speed of light for its ships. But a culture spread over hundreds of light-years would be unthinkable without something permitting instant communication between its parts.
"All right!" said Holmes doggedly. "Call them transposers! This fortress had to be supplied. We've found no sign that ships were used to supply it. It needed to have its air renewed and refreshed. We've found no sign of anything but emergency stores of air in case some unknown air-supply system failed. What's the matter with looking for a matter-transposer?"
Burke said, "In a way, a telephone system transposes sound-waves from one place to another. Sound-waves aren't carried along wires. They're here, and then suddenly they're there. But there has to be a sending and receiving station at each end. When the fortress here was 'cut off' from home it could be that its supply-system broke down."
"Its air-system didn't," said Holmes. "It hadn't used up its emergency air-supply. We're breathing it!"
"Anyhow we could try to find even a broken-down transposer," said Sandy.
"You try," said Burke. "Keller's been looking for something for me in the cubes. I'll stay here and help him look."
Sandy examined the weapon he'd given her.
"Pam says she's smelled fresh air, down below where there can't be any. Mr. Keller thought he saw movements in the inside vision-plates, where there can't be any. I still believe I saw something alive in the gravity-machine room, where such a thing is impossible. We're going to look, Pam and I."
Holmes lumbered to his feet.
"I'll come, too. And I'll guarantee to defend you against anything that has survived the ten thousand years or so that this place was without air. My head's tired, after all those cubes."
He led the way. Burke watched as the two girls followed him and closed the door behind them.
"What have you found, Keller?"