From a sufficient height and a sufficient distance, the rocket's repeated attacks must have appeared like the strikings and twistings of a gigantic snake. It left behind it a writhing trail of fumes which was convincingly serpentine. It climbed and struck, and climbed and struck, like a monstrous python flinging itself furiously at some invisible prey. Six, seven, eight times it plunged frenziedly at the minute egg-shaped ship which scuttled for the heavens. Each time it missed and writhed about to dart again.

Then its fuel gave out and for all intents and purposes it ceased to exist. The thick, opaque trail it left behind began to dissipate. The path of vapor scattered. It spread to rags and tatters of unsubstantiality through which the rocket plummeted downward in the long fall which is a spent rocket's ending.

Burke cautiously cut down the drive and awkwardly turned the ship on its side, heading it toward the north. The state of things inside the ship was one of intolerable tenseness.

"I'm a new driver," said Burke, "and that was a tough bit of driving to do." He glanced at the exterior-pressure meter. "There's no air outside to register. We must be fifty or sixty miles high and maybe still rising. But we're not leaking air."

Actually the plastic ship was eighty miles up. The sunlit world beneath it showed white patches of cloud in patterns a meteorologist would have found interesting. Burke could see the valley of the St. Lawrence River between the white areas. But the Earth's surface was curiously foreshortened. What was beneath seemed utterly flat, and at the edge of the world all appeared distorted and unreal.

Holmes, still pale, asked, "How'd we get away from that rocket?"

"We accelerated," said Burke. "It was a defensive rocket. It was designed to knock down jet bomb carriers or ballistic missiles which travel at a constant speed. Target-seeking missiles can lock onto the radar echo from a coasting ship, or one going at its highest speed because their computers predict where their target, traveling at constant speed, can be intercepted. We were never there. We were accelerating. Missile-guidance systems can't measure acceleration and allow for it. They shouldn't have to."

Four of the six television screens showed dark sky with twinkling lights in it. On one there was the dim outline of the sun, reversed to blackness because its light was too great to be registered in a normal fashion. The other screen showed Earth.

There was a buzzing, and Keller looked at Burke.

"Rocket?" asked Burke. Keller shook his head. "Radar?" Keller nodded.

"The DEW line, most likely," said Burke in a worried tone. "I don't know whether they've got rockets that can reach us. But I know fighter planes can't get this high. Maybe they can throw a spread of air-to-air rockets, though.... I don't know their range."

Sandy said unsteadily, "They shouldn't do this to us! We're not criminals! At least they should ask us who we are and what we're doing!"

"They probably did," said Burke, "and we didn't answer. See if you can pick up some voices, Keller."

Keller twirled dials and set indicators. Voices burst into speech. "Reporting UFO sighted extreme altitude coÖrdinates—First rocket exhausted fuel in multiple attacks and fell, sir." Another voice, very brisk, "Thirty-second squadron, scramble! Keep top altitude and get under it. If it descends within range, blast it!" Another voice said crisply, "CoÖrdinates three-seven Jacob, one-nine Alfred...."

Keller turned the voices down to mutters because they were useless.

Burke said, "Hell! We ought to land somewhere and check over the ship. Keller, can you give me a microphone and a wavelength somebody will be likely to pick up?"

Keller shrugged and picked up masses of wire. He began to work on an as yet unfinished wiring job. Evidently, the ship was not near enough to completion to be capable of a call to ground. It had taken off with many things not finished. Burke, at the controls, found it possible to think of a number of items that should have been examined exhaustively before the ship left the mould in which it had been made. He worried.

Pam said in a strange voice, "I thought I might rate as a heroine for stowing away on this voyage, but I didn't think we'd have to dodge rockets and fighter planes to get away!"

There was no comment.

"I'm a beginner at navigation," said Burke a little later, more worried than before. "I know we have to go out over the north magnetic pole, but how the hell do I find that?"

Keller beamed. He dropped his wiring job and went to the imposing bank of electronic instruments. He set one, and then another, and then a third. The action, of course, was similar to that of an airline pilot when he tunes in broadcasting stations in different cities. From each, a directional reading can be taken. Where the lines of direction cross, there the transport plane must be. But Keller turned to shortwave transmitters whose transmissions could be picked up in space. Presently, eighty miles high, he wrote a latitude and longitude neatly on a slip of paper, wrote "North magnetic pole 93°W, 71°N, nearly," and after that a course.

"Hm," said Burke. "Thanks."

Then there was a relative silence inside the ship. Only a faint mutter of voices came from assorted speakers that Keller had first turned on and then turned down, and a small humming sound from a gyro. When they listened, they could also hear a high sweet musical tone. Burke shifted this control here, and that control there, and lifted his hands. The ship moved on steadily. He checked this and that and the other thing. He was pleased. But there were innumerable things to be checked. Holmes went down the ladder to the other compartment below. There were details to be looked into there, too.

One of the screens portrayed Earth from a height of seventy miles instead of eighty, now. Others pictured the heavens, with very many stars shining unwinkingly out of blackness. Keller got at his wires again and resumed the work of installing a ship-to-ground transmitter and its connection to an exterior-reflecting antenna.

Sandy watched Burke as he moved about, testing one thing after another. From time to time he glanced at the screens which had to serve in the place of windows. Once he went back to the control-board and changed an adjustment.

"We dropped down ten miles," he explained to Sandy. "And I suspect we're being trailed by jets down below."

Holmes meticulously inspected all storage places. He'd packed them when the ship lay on her side.

Burke read an instrument and said with satisfaction, "We're running on sunshine!"

He meant that in empty space certain aluminum plates on the outside of the hull were picking up heat from the naked sun. The use of the drive-shaft lowered its temperature. Metallic connection with the outside plates conducted heat inward from those plates. The drive-shaft was cold to the touch, but it could drop four hundred degrees Fahrenheit before it ceased to operate as a drive. It was gratifying that it had cooled so little up to this moment.

Later Keller tapped Burke on the shoulder and jerked his thumb upward.

"We go up now?" asked Burke.

Keller nodded. Burke carefully swung the ship to aim vertically. The views of solid Earth slid from previous screens to new ones. The stars and the dark object which was the sun also moved across their screens to vanish and reappear on others. Then Burke touched the drive-control. Once more they had the sensation of being in a rising elevator. And at just that moment spots appeared on the barren, icy, totally flattened terrain below.

They were rocket-trails from target-seeking missiles which had reached the area of the north magnetic pole by herculean effort and were aimed at the radar-detected little ship by the heavy planes that carried them.

From the surface of the Earth, it would have seemed that monstrous columns of foaming white appeared and rose with incredible swiftness toward the heavens. They reached on, up and up and up, seeming to draw closer together as they became smaller in the distance, until all eight of them seemed to merge into a single point of infinite whiteness in the sunshine above the world's blanket of air.

But nothing happened. Nothing. The ship did not accelerate as fast as the rockets, but it had started first and it kept up longer. It went scuttling away to emptiness and the bottoms of the towers of rocket-smoke drifted away and away over the barren landscape all covered with ice and snow.

When Earth looked like a huge round ball that did not even seem very near, with a night side that was like a curious black chasm among the stars, the atmosphere of tension inside the ship diminished. Keller completed his wiring of a ship-to-ground transmitter. He stood up, brushed off his hands and beamed.

The little ship continued on. Its temperature remained constant. The air in it smelled of growing green stuff. It was moist. It was warm. Keller turned a knob and a tiny, beeping noise could be heard. Dials pointed, precisely.

"We couldn't go on our true course earlier," Burke told Sandy, "because we had to get out beyond the Van Allen bands of cosmic particles in orbit around the world. Pretty deadly stuff, that radiation! In theory, though, all we have to do now is swing onto our proper course and follow those beepings home. We ought to be in harmless emptiness here. Do you want to call Washington?"

She stared.

"We need help to navigate—or astrogate," said Burke. "Call them, Sandy. I'll get on the wire when a general answers."

Sandy went jerkily to the transmitter just connected. She began to speak steadily, "Calling Earth! Calling Earth! The spaceship you just shot all those rockets at is calling! Calling Earth!"

It grew monotonous, but eventually a suspicious voice demanded further identification.

It was a peculiar conversation. The five in the small spaceship were considered traitors on Earth because they had exercised the traditional right of American citizens to go about their own business unhindered. It happened that their private purposes ran counter to the emotional state of the public. Hence voices berated Sandy and furiously demanded that the ship return immediately. Sandy insisted on higher authority and presently an official voice identified itself as general so-and-so and sternly commanded that the ship acknowledge and obey orders to return to Earth. Burke took the transmitter.

"My name's Burke," he said mildly. "If you can arrange some sort of code, I'll tell you how to find the plans, and I'll give you the instructions you'll need to build more ships like this. They can follow us out. I think they should. I believe that this is more important than anything else you can think of at the moment."

Silence. Then more sternness. But ultimately the official voice said, "I'll get a code expert on this."

Burke handed the microphone to Sandy.

"Take over. We've got to arrange a cipher so nobody who listens in can learn about official business. We may use a social security number for a key, or the name of your maiden aunt's first sweetheart, or something we know and Washington can find out but that nobody else can. Hm. Your last year's car-license number might be a starter. They can seal up the records on that!"

Sandy took over the job. What was transmitted to Earth, of course, could be picked up anywhere over an entire hemisphere. Somebody would assuredly pass on what they overheard to, say, nations the United States would rather have behind it than ahead of it in space-travel equipment. Burke's suggestion of a cipher and instructions changed his entire status with authority. They'd rather have had him come back, but this was second best, and they took it.

From Burke's standpoint it was the only thing to do. He had no official standing to lend weight to his claim that lunatic magnet-cores with insanely complicated windings would amount to space-drive units. If he returned, in the nature of things there would be a long delay before mere facts could overcome theoreticians' convictions. But now he was forty-five thousand miles out from Earth.

He had changed course to home on the beeping signals from M-387, was accelerating at one full gravity and had been doing so for forty-five minutes. And the small ship already had a velocity of twenty miles per second and was still going up. All the rockets that men had made, plus the Russian manned-probe drifting outward now, had become as much outdated for space travel as flint arrowheads are for war.

Burke returned to the microphone when Sandy left it to get a pencil and paper.

"By the way," he said briskly. "We can keep on accelerating indefinitely at one gravity. We've got radars. We got them from—" He named the supplier. "Now we want advice on how fast we can risk traveling before we'll be going too fast to dodge meteors or whatnot that the radar may detect. Get that figured out for us, will you?"

He gave back the instrument to Sandy and returned to his inspection of every item of functioning equipment in the ship. He found one or two trivial things to be bettered. The small craft went on in a singularly matter-of-fact fashion. If it had been a bomb shelter buried in the pit beside the mould in which it was built, there would have been very little difference in the feel of things. The constant acceleration substituted perfectly for gravity. The six television screens, to be sure, pictured incredible things outside, but television screens often picture incredible things. The wall-gardens looked green and flourishing. The pumps were noiseless. There were no moving parts in the drive. The gyro held everything steady. There was no vibration.

Nobody could remain upset in such an unexciting environment. Presently Pam explored the living quarters below. Holmes took his place in the control-chair, but found no need to touch anything.

Some time later Sandy reported, "Joe, they say we must be lying, but if we can keep on accelerating, we'd better not hit over four hundred miles a second. They say we can then swing end for end and decelerate down to two hundred, and then swing once more and build up to four again. But they insist that we ought to return to Earth."

"They don't mention shooting rockets at us, do they?" asked Burke. "I thought they wouldn't. Just say thanks and go on working out a code."

Sandy set to work with pencil and paper. Federal agents would be moving, now, to impound all official records that were in any way connected with any of the five on the ship. The key to the code would be contained in such records. It would be an agglomeration of such items as Burke's grandmother's maiden name, Holmes' social-security number, the name of a street Burke had lived on some years before, the exact amount of his federal income taxes the previous year, the title of a book third from the end on the second shelf of a bookcase in Keller's apartment, and such unconsidered items as most people can remember with a little effort, but which can only be found out by people who know where to look. These people would keep anybody else from looking in the same places. Such a code would be clumsy to work with, but it would be unbreakable.

It took hours to establish it without the mention of a single word included in the lengthy key. The ship reached four hundred miles a second, turned about, and began to cut down its speed again.

Pam spoke from beside an electric stove, "Dinner's ready! Come and get it!"

They dined; Sandy weary, Burke absorbed and inevitably worried, Holmes placid and amiable, and Keller beaming and interested in all that went on, which was practically nothing.

They did not see the stars direct, because television cameras were preferable to portholes. Earth had become very small, and as it swung ever more nearly into a direct line between the ship and the sun, night filled more of its disk until only a hairline of sunshine showed at one edge. The microwave receivers ceased to mutter. The working astronomers on Earth who'd sent a message to M-387 were suddenly relieved of their disgrace and set to work again to equip the West Virginia radar telescope for continuous communication with Burke's ship. Other technicians began to prepare multiple receptors to pick up the ship's signals from hitherto unprecedented distances for human two-way communication.

And on Earth an official statement went out from high authority. It announced that a hurriedly completed American ship was on the way to M-387 to investigate the signals from space. It announced that measures long in preparation were now in use, and that an invincible fleet of spacecraft would be completed in months, whereas they had not been hoped for for another generation. An unexpected breakthrough had made it possible to advance the science of space travel by many decades, and a fleet to explore all the planets as well as M-387 was already under construction. It was almost true that they were. The blueprints of Burke's ship had been flown to Washington from the plant, and an enormous number of replicas of the egg-shaped vessel were ordered to be begun immediately, even before the theory of the drive was understood.

There was one minor hitch. A legal-minded official protested that Congressional appropriations had been for rocket-driven spaceships only, and the money appropriated could not be used for other than rockets. An executive order settled the matter. Then theorists began to object to the principle of the drive. It contradicted well-established scientific beliefs. It could not work.

It did, but there was violent opposition to the fact.

Publicly, of course, the shock of such an about-face by the national government was extreme. But newspapers flashed new headlines. "U.S. SHIP SPEEDING TO QUERY ALIENS!" Lesser heads announced, "Critical Velocity Exceeded! Russian Probe Already Passed!" The last was not quite true. The Russian manned probe had started out ten days before. Burke hadn't overtaken it yet.

Broadcasters issued special bulletins, and two networks canceled top evening programs to schedule interviews with prominent scientists who'd had nothing whatever to do with what Burke had managed to achieve.

In Europe, obviously, the political effect was stupendous. Russia was reduced to impassioned claims that the ship had been built from Russian plans, using Russian discoveries, which had been stolen by imperialistic secret agents. And the heads of the Russian spy system were disgraced for not having, in fact, stolen the plans and discoveries from the Americans. All other operatives received threats of what would happen to them if they didn't repair that omission. These threats so scared half a dozen operatives that they defected and told all they knew, thereby wrecking the Russian spy system for the time being.

Essentially, however, the recovery of confidence in America was as extravagant as the previous unhappy desire to hear no more about space. Burke, Holmes, Keller, Sandy and Pam became national heroes and heroines within eighteen hours after guided missiles had failed to shoot them down. The only criticism came from a highly conservative clergyman who hoped that other young girls would not imitate Sandy's and Pam's disregard of convention and maintained that a married woman should have gone along to chaperon them.

The atmosphere in the ship, however, was that of respectability carried to the point where things were dull. The lower compartment of the ship, being smaller, was inevitably appropriated by Sandy and Pam. They retired when the ship was twenty hours out from Earth. Each of them had prepared for stowing away by wearing extra garments in layers.

"Funny," said Pam, yawning as they made ready to turn in, "I thought it was going to be exciting. But it's just like a rather full day at the office."

"Which," said Sandy, "I'm quite used to."

"I do think you ought to have barged in when they designed the ship, Sandy. There's not one mirror in it!"

In the upper compartment Keller took his place in the control-chair and took a trick of duty. It consisted solely of looking at the instruments and listening to the beeping noises which came from remoteness every two seconds, and the still completely cryptic broadcasts which came every seventy-nine minutes. It wasn't exciting. There was nothing to be excited about. But somebody had to be on watch.

On the second day out, Washington was ready to use the new code. The West Virginia radar bowl was powered to handle communications again. Sandy painstakingly took down the gibberish that came in and decoded it. From then on she worked at the coding and transmission of messages and the reception and decoding of others. Presently Pam relieved her at the job. Pam tended to be bored because Holmes was as much absorbed in the business of keeping anything from happening as was Burke.

The messages were almost entirely requests for, and answers to requests for, details about the ship plans. The United States had not yet completed a duplicate drive-shaft. Machinists labored to reproduce the cores, which would then have to be wound in the complicated fashion the plans described. But it was an unhappy experience for the scientific minds assigned to duplicate Burke's ship. No woman ever followed a recipe without making some change. Very few physicists can duplicate another's apparatus without itching to change it. There were six copies of the drive under construction at the same time, at the beginning. Four were made by skeptics, who adhered to the original plans with strict accuracy. They were sure they'd prove Burke wrong. Two were "improved" in the making. The four, when finished, worked beautifully. The two doctored versions did not. But still there was fretful discussion of the theory of the drive. It seemed flatly to contradict Newton's law that every action has a reaction of equal moment and opposite sign—a law at least as firmly founded as the law of the conservation of energy. But that had lately been revised into the law of the conservation of energy and matter, which now was gospel. Burke's theory required the Newtonian law to be restated to read "every action of a given force has a reaction of the same force, of the same moment," and so on. When the reaction of one force is converted into another force, the results can be interesting. In fact, one can have a space-drive. But there was bitter resistance to the idea. It was demanded that Burke justify his views in a more reasonable way than by mere demonstration that they worked.

After a time, Burke gave up trying to explain things. And when one and then another duplicate drive worked, the argument ceased. But eminent physicists still had a resentful feeling that Burke was cheating on them somehow.

Then for days nothing happened. One of the three men in the ship always stayed in the control-chair where he could check the ship's course against the homing signals from the asteroid. He might have to correct it by the fraction of a hair, or swing ship and put on more drive if the radar should show celestial debris in the spaceship's path. Every so many hours the ship had to be swung about so that instead of accelerating she decelerated, or instead of decelerating gained fresh speed. But that was all.

On the fifth day there was the flash of a meteor on the radar. On the seventh day an object which could have been the second or third unmanned Russian probe showed briefly at the very edge of the radar screens. In essence, however, the journey was pure tedium. Burke wearied of making sure that his work was good, though he congratulated himself that nothing did happen to break the monotony. Holmes admitted that he was disappointed. He'd wanted to make the journey because he'd sailed in everything but a spaceship. But there was no fun in it. Keller alone seemed comfortably absorbed. He prepared daily lists of instrument-readings to be sent back to Earth. They would be of enormous importance to science-minded people. They were not of interest to Sandy.

Even when she talked to Burke, it was necessarily impersonal. There could be no privacy which was not ostentatious. The two girls used the lower compartment, the three men the upper and larger one. For Sandy to talk privately with Burke, she'd have had to go to the small bottom section of the ship. Holmes and Pam faced the same situation. It was uncomfortable. So they developed a perfectly pleasant habit of talking exclusively of things everybody could talk about. It did not bother Keller, who would hardly average a dozen words in twenty-four hours, but Sandy muttered to herself when she and Pam retired for what was a ship-night's rest.

When they went past the orbit of Mars, agitated instructions came out from Earth. The asteroid belts began beyond Mars. Elaborate directions came. The ship was tracked by radar telescopes all around the world, direction-finding on its transmission. Croydon kept track. American radar bowls picked up the ship's voice. South American and Hawaiian and Japanese and Siberian radar telescopes determined the ship's position every time a set of code symbols reached Earth from the ship. Of course, there were also the beepings and the seventy-nine-minute-spaced identical broadcasts from farther out from the sun.

Somebody got a brilliant idea and authority to try it. An interview for broadcast on Earth was sought with somebody on the ship. It was then a hundred thirty million miles from Earth, and ninety-two million more from the sun. Largely out of boredom Sandy agreed to answer questions. But at the speed of light it required eleven minutes to reach her from Earth, and as long for her reply to be received. It did not make for liveliness, so she spoke curtly for five minutes and stopped. She talked at random about housekeeping in space. Without knowing it, she was praised for her domesticity in many pulpits the following Sunday, and eight hundred ninety-two proposals of marriage piled up in mail addressed to her in care of the United States government. Twelve were in Russian.

But nothing really exciting happened aboard the spaceship. It was Burke's guess that they could go directly through the asteroid belt along the plane of the ecliptic, and not get nearer than ten thousand miles to any bit of shattered stone or metal in orbit out there. He was almost right. There was only one occasion when his optimism came into doubt.

It was on the ninth day out from Earth. Experimentally, the ship coasted on attained momentum, using no drive. There was, then, no substitute for gravity and everyone and everything in the ship was weightless. The power obtainable from the sun as heat had dwindled to one-ninth of that at the Earth's distance. But what was received could be stored, and was. Meanwhile the ship plunged onward at very nearly four hundred miles per second. Burke, Keller, and Holmes together labored over a self-contained diving suit which they hoped could be used as a space suit in dire emergency and for brief periods. They wanted to get the feel of using it with internal pressure and weightlessness as conditions. Sandy sat at the transmitter, working at code which by now she heartily loathed. Pam sat in the control-chair, watching the instruments.

There was a buzz. Burke snapped his head around to see the radar screen. A line of light appeared on it. It aimed directly at the center of the screen, which meant that whatever had been picked up was on a collision course with the ship. Burke plunged toward the control-chair to take over. But he'd forgotten the condition of no-gravity. He went floating off in mid-air, far wide of the chair.

He barked orders to Pam, who was least qualified of anybody aboard to meet an emergency of this sort. She panicked. She did nothing. Holmes took precious seconds to drag himself to the controls by what hand-holds could be had. The glowing white line on the radar screen lengthened swiftly. It neared the center. It reached the center. Burke and Holmes froze.

There was a curious flashing change in a vision-screen. An image flashed into view. It was a jagged, tortured, irregularly-shaped mass of stone or metal, distorted in its representation by the speed at which it passed the television lens. It was perhaps a hundred yards in diameter. It could never have been seen from Earth. It might circle the sun in its lonely orbit for a hundred million years and never be seen again.

It went away to nothing. It had missed by yards or fathoms, and Burke found himself sweating profusely. Holmes was deathly white. Keller very carefully took a deep breath, swallowed, and went back to his work on the diving-suit-qua-space-suit. Sandy hadn't noticed anything at all. But Pam burst into abrupt, belated tears, and Holmes comforted her clumsily. She was bitterly ashamed that she'd done nothing to meet the emergency which came while she was at the control-board, and which was the only emergency they'd encountered since the ship's departure from Earth.

After that, they put on the drive and used reserve fuel. It was necessary to check their speed, anyhow. They were very near the source of the beeping signal they'd steered by for so long. The directional receiver pointed to it had long since been turned down to its lowest possible volume, and still the beepings were loud.

On the eleventh day after their take-off, they sighted Asteroid M-387. They had traveled two hundred seventy million miles at an averaged-out speed of very close to three hundred miles per second. Despite muting, the beepings from the loud-speakers were monstrous noises.

"Try a call, Holmes," said Burke. "But they ought to know we're here."

He felt strange. He'd brought the ship to a stop about four or five miles from M-387. The asteroid was a mass of dark stuff with white outcroppings at one place and another. The ship seemed to edge itself toward it. The floating mass of stone and metal had no particular shape. It was longer than it was wide, but its form fitted no description. A mountain which had been torn from solidity with its roots of stone attached might look like Schull's Object as it turned slowly against a background of myriads of unblinking stars.

There was no change in the beeping that came from the singular thing. It did rotate, but so slowly that one had to watch for long minutes to be sure of it. There was no outward sign of any reaction to the ship's presence. Holmes took the microphone.

"Hello! Hello!" he said absurdly. "We have come from Earth to find out what you want."

No answer. No change in the beeping calls. The asteroid turned with enormous deliberation.

Sandy said suddenly, "Look there! A stick! No, it's a mast! See, where the patch of white is?"

Burke very, very gingerly drew closer to the monstrous thing which hung in space. It was true. There was a mast of some sort sticking up out of white stone. The direction-indicators pointed to it. The beeping stopped and a broadcast began. It was the standard broadcast Earth heard every seventy-nine minutes.

There was no reply to Holmes' call. There was no indication that the ship's arrival had been noted. On Earth the ignoring of human broadcasts to M-387 had seemed arrogance, indifference, a superior and menacing contempt for man and all his works; somehow, here the effect was different. This irregular mass was a fragment of something that once had been much greater. It suddenly ceased to seem menacing because it seemed oblivious. It acted blindly, by rote, like some mechanism set to operate in a certain way and unable to act in any other.

It did not seem alive. It had signaled like a robot beacon. Now it felt like one. It was one.

"Look, coming around toward us," said Holmes very quietly. "There's something that looks like a tunnel. It's not a crevasse. It was cut."

Burke nodded.

"Yes," he said thoughtfully. "I think we'll explore it. But I don't really expect we'll find any life here. There's nothing outside to see but a single metal mast. We've got some signal lights on our hull. If we're careful—"

No one objected. The appearance of the asteroid was utterly disappointing. Its lifelessness and its obliviousness to their coming and their calls were worse than disappointing. There was nothing to be seen but a metal stick from which signals went out to nowhere.

Burke jockeyed the little ship to the tunnel-mouth. It was fully a hundred feet in diameter. He turned on the ship's signal lights. Gently, cautiously, he worked down the very center of the very large bore.

It was perfectly straight. They went in for what seemed an indefinite distance. Presently the signal lights showed that the wall was smoothed. The bore grew smaller still. They went on and on.

Suddenly Keller grunted. He pointed to one of the six television screens which aimed out the length of the tunnel and showed the stars beyond.

Those stars were being blotted out. Something vast moved slowly and deliberately across the shaft they navigated. It closed the opening. Their retreat was blocked. The ship was shut in, in the center of a mountain of stone which floated perpetually in emptiness. Burke checked the ship's forward motion, judging their speed by the side walls shown by the ship's outside lights.

Very, very slowly, faint illumination appeared outside. In seconds they could see that the light came from long tubes of faint bluish light. The light changed. It grew stronger. It turned green and then yellowish and then became very bright, indeed.

Then nothing more took place. Nothing whatever. The five inside the ship waited more than an hour for some other development, but absolutely nothing happened.