Earthlight (Arthur C. Clarke Collection)

by Arthur C. Clarke

  Sadler could now look down into the depths without flinch­ing. Infinitely far below, it seemed, some strange insects were slowly crawling back and forth in little pools of artificial light. If one shone a torch upon a group of cockroaches, they would have looked like this.

  But those tiny insects, Sadler knew, were the great mining machines at work on the floor of the canyon. It was surprisingly flat down there, so many thousands of meters below, for it

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  seemed that lava had flooded into the cleft soon after it was formed, and then congealed into a buried river of rock.

  The Earth, almost vertically overhead, illuminated the great wall immediately opposite. The canyon marched away to right and left as far as the eye could follow, and sometimes the blue-green light falling upon the rock face produced a most unex­pected illusion. Sadler found it easy to imagine, if he moved his head suddenly, that he was looking into the heart of a gigantic waterfall, sweeping down forever into the depths of the Moon.

  Across the face of that fall, on the invisible threads of hoist­ing cables, the ore buckets were rising and dropping. Sadler had seen those buckets, moving on the overhead lines away from the Cleft, and he knew that they were taller than he was. But now they looked like beads moving slowly along a wire, as they carried their loads to the distant smelting plants. It's a pity, he thought to himself, that they're only carrying sulphur and oxy­gen and silicon and aluminum—we could do with fewer of the light elements and more of the heavy ones.

  But he had been called here on business, not to stand gaping like a tourist. He pulled the coded notes from his pocket, and began to give his report.

  It did not take as long as he could have wished. There was no way of telling whether his listener was pleased or disap­pointed at the inconclusive summary. He thought it over for a minute, then remarked, "I wish we could give you some more help, but you can imagine how shorthanded we are now. Things are getting rough; if there is going to be trouble, we expect it in the next ten days. There's something happening out around Mars, but we don't know what it is. The Federation has been building at least two ships of unusual design, and we think they're testing them. Unfortunately we haven't a single sighting, only some rumors that don't make sense but have worried De­fense. I'm telling you this to give you more background. No one here should know about it, and if you hear anybody talking on these lines it will mean that they've somehow had access to classified information.

  "Now about your short list of provisional suspects. I see you've got Wagnall down, but he's clear with us."

  "O.K. I'll move him to List B."

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  "Then Brown, Lefevre, Tolanski—they've certainly had no contacts here."

  "Can you be sure of that?"

  "Fairly. They use their off-duty hours here in highly non-political ways."

  "I'd suspected that," Sadler remarked, permitting himself the luxury of a smile. "I'll take them off altogether."

  "Now this man Jenkins, in Stores. Why are you so keen on keeping him?"

  "I've no real evidence at all. But he seems about the only person who's taken any objection to my nominal activities."

  "Well, we'll continue to watch him from this end. He comes to town quite often, but of course he's got a good excuse—he does most of the local purchasing. That leaves you with five names on your A list, doesn't it?"

  "Yes, and frankly, I'll be very surprised if it's any of them. Wheeler and Jamieson we've already discussed. I know that Maclaurin's suspicious of Jamieson after that trip out to the Mare Imbrium, but I don't put much reliance on that. It was largely Wheeler's idea, anyway.

  "Then there are Benson and Carlin. Their wives come from Mars, and they keep getting into arguments whenever the news is being discussed. Benson's an electrician in Tech Maintenance; Carlin's a medical orderly. You could say they have some motive, but it's a pretty tenuous one. Moreover, they'd be rather too obvious suspects."

  "Well, here's another we'd like you to move up to your List A. This fellow Molton."

  "Dr. Molton?" exclaimed Sadler in some surprise. "Any particular reason?"

  "Nothing serious, but he's been to Mars several times on astronomical missions and has some friends there."

  "He never talks politics. I've tackled him once or twice and he just didn't seem interested. I don't think he meets many people in Central City—he seems completely wrapped up in his work and I think he only goes into town to keep fit in the gym. You've nothing else?"

  "No—sorry. It's still a fifty-fifty case. There's a leak some­where, but it may be in Central City. The report about the

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  Observatory may be a deliberate plant. As you say, it's very hard to see how anyone there could pass on information. The radio monitors have detected nothing except a few unauthorized per­sonal messages which were quite innocent."

  Sadler closed his notebook and put it way with a sigh. He glanced once more down into the vertiginous depths above which he was so insecurely floating. The cockroaches were crawl­ing briskly away from a spot at the base of the cliff, and suddenly a slow stain seemed to spread across the floodlit wall. (How far down was that? Two kilometers? Or three?) A puff of smoke emerged, and instantly dispersed into the vacuum. Sadler began to count the seconds to time his distance from the explosion, and had got to twelve before he remembered that he was wasting his efforts. If that had been an atom bomb, he would have heard nothing here.

  The man in blue adjusted his camera strap, nodded at Sadler, and became the perfect tourist again.

  "Give me ten minutes to get clear," he said, "and remember not to know me if we meet again."

  Sadler rather resented that last advice. After all, he was not a complete amateur. He had been fully operational for almost half a lunar day.

  Business was slack at the little cafe in the Hyginus station, and Sadler had the place to himself. The general uncertainty had discouraged tourists; any who happened to be on the Moon were hurrying home as fast as they could get shipping space. They were probably doing the right thing; if there was trouble, it would be here. No one really believed that the Federation would attack Earth directly and destroy millions of innocent lives. Such barbarities belong to the past—so it was hoped. But how could one be sure? Who knew what might happen if war broke out? Earth was so fearfully vulnerable.

  For a moment Sadler lost himself in reveries of longing and self-pity. He wondered if Jeannette had guessed where he was. He was not sure, now, that he wanted her to know. It would only increase her worries.

  Over his coffee—which he still ordered automatically though he had never met any on the Moon worth drinking—he

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  considered the information his unknown contact had given to him. It had been of very little value; he was still groping in the dark. The tip about Molton was a distinct surprise, and he did not take it too seriously. There was a kind of trust­worthiness about the astrophysicist which made it hard to think of him as a spy. Sadler knew perfectly well that it was fatal to rely on such hunches, and whatever his own feelings, he would now pay extra attention to Molton. But he made a private bet with himself that it would lead nowhere.

  He marshaled all the facts he could remember about the head of the Spectroscopy Section. He already knew about Mol-ton's three trips to Mars. The last visit had been over a year ago, and the director himself had been there more recently than that. Moreover, among the interplanetary brotherhood of astronomers, there was probably no member of the senior staff who did not have friends on both Mars and Venus.

  Were there any unusual features about Molton? None that Sadler could think of, apart from that curious aloofness that seemed to conflict with a real inner warmth. There was, of course, his amusing and rather touching "flower-bed," as he had heard someone christen it. But if he was to start investigat­ing innocent eccentricities like that, he'd never get anywhere.

  -There was one thing that might be worth looking into, how­ever. He'd make a note of the shop where Molton
purchased his replacements (it was almost the only place outside the gym he ever visited), and one of the counter-agents in the city could sniff around it. Feeling rather pleased with himself at thus proving he was missing no chances, Sadler paid his bill and walked up the short corridor connecting the cafe with the almost deserted station.

  He rode the spur-line back to Central City, over the in­credibly broken terrain past Triesnecker. For almost all the journey, the monorail track was accompanied by the pylons passing their loaded buckets out from Hyginus, and the empty ones back. The long cables, with their kilometer spans, were the cheapest and most practical means of conveyance—if there was no particular hurry to deliver the goods. Soon after the domes of Central City appeared on the skyline, however, they changed direction and curved off to the right. Sadler could see

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  them marching away down to the horizon toward the great chemical plants which, directly or indirectly, fed and clothed every human being on the Moon.

  He no longer felt a stranger in the city, and went from dome to dome with the assurance of a seasoned traveler. The first priority was an overdue haircut; one of the Observatory cooks earned some extra money as a barber, but having seen the re­sults, Sadler preferred to stick to the professionals. Then there was just time to call at the gym for fifteen minutes in the centrifuge.

  As usual, the place was full of Observatory staff making sure they would be able to live on Earth again when they wished to. There was a waiting list for the centrifuge, so Sadler dumped his clothes in a locker and went for a swim until the descend­ing whine of the motor told him that the big machine was ready for a new cargo of passengers. He noticed, with wry amusement, that two of his List-A suspects—Wheeler and Molton—and no less than seven of the Class-B ones were present. But it was not so surprising about Class B. Ninety per cent of the Observatory staff were on that unwieldly list, which if it had been titled at all would have been called: "Persons sufficiently intelligent and active to be spies, but con­cerning whom there is no evidence one way or the other."

  The centrifuge held six people, and had some ingenious safety device which prevented its starting unless the load was properly balanced. It refused to co-operate until a fat man on Sadler's left had changed places with a thin man opposite; then the motor began to pick up speed and the big drum with its slightly anxious human cargo started to turn on its axis. As the speed increased, Sadler felt his weight steadily mounting. The direction of the vertical was shifting, too—it was swinging round toward the center of the drum. He breathed deeply, and tried to see if he could lift his arms. They felt as if they were made of lead.

  The man on Sadler's right staggered to his feet and began to walk to and fro, keeping within the carefully defined white lines that marked the limits of his territory. Everyone else was doing the same; it was uncanny to watch them standing on what, from the point of view of the Moon, was a vertical sur-

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  face. But they were glued to it by a force six times as great as the Moon's feeble gravity—a force equal to the weight they would have had on Earth.

  It was not a pleasant sensation. Sadler found it almost im­possible to believe that until a few days ago he had spent his entire existence in a gravity field of this strength. Presumably he would get used to it again, but at the moment it made him feel as weak as a kitten. He was heartily glad when the centri­fuge slowed down and he was able to crawl back into the gentle gravity of the friendly Moon.

  He was a tired and somewhat discouraged man as the mono­rail pulled out of Central City. Even the brief glimpse he caught of the new day, as the still-hidden sun touched the highest pinnacles of the western mountains, failed to cheer him. He had been here more than twelve days of Earth time, and the long lunar night was ending. But he dreaded to think what the day might bring.

  Chapter XIII

  every man has his weakness, if you can find it. Jamieson's was so obvious that it seemed unfair to exploit it, but Sadler could not afford to have any scruples. Everyone in the Observa-tary regarded the young astronomer's painting as a subject for mild amusement, and gave him no encouragement at all. Sad­ler, feeling a considerable hypocrite, began to play the role of sympathetic admirer.

  It had taken some time to break through Jamieson's reserve and to get him to speak frankly. The process could not be hur­ried without arousing suspicion, but Sadler had made fair progress by the simple technique of supporting Jamieson when his colleagues ganged up on him. This happened, on the average, every time he produced a new picture.

  To steer the conversation from art to politics took less skill than might have been expected, for politics was never very far away these days. Yet oddly enough, it was Jamieson himself who raised the questions that Sadler had been trying to ask.

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  He had obviously been thinking hard, in his methodical way, wrestling with the problem that had concerned every scien­tist, to a greater and greater extent, since the day when atomic power was born on Earth.

  "What would you do," he asked Sadler abruptly, a few hours after the latter's return from Central City, "if you had to chose between Earth and the Federation?"

  "Why ask me?" replied Sadler, trying to conceal his interest.

  "I've been asking a lot of people," Jamieson replied. There was a wistfulness in his voice, the puzzled wonder of someone looking for guidance in a strange and complex world. "Do you remember that argument we had in the Common Room, when Mays said that whoever believed in 'my planet, right or wrong' was a fool?"

  "I remember," Sadler answered cautiously.

  "I think Mays was right. Loyalty isn't just a matter of birth, but ideals. There can be times when morality and patri­otism clash."

  "What's started you philosophizing on these lines?"

  Jamieson's reply was unexpected.

  "Nova Draconis," he said. "We've just got in the reports from the Federation observatories out beyond Jupiter. They were routed through Mars, and someone there had attached a note to them—Molton showed it to me. It wasn't signed, and it was quite short. It merely said that whatever happened—and the word was repeated twice—they'd see that their reports con­tinued to reach us."

  A touching example of scientific solidarity, thought Sadler; it had obviously made a deep impression on Jamieson. Most men—certainly most men who were not scientists—would have thought the incident rather trivial. But trifles like this could sway men's minds at crucial moments.

  "I don't know just what you deduce from this," said Sad­ler, feeling like a skater on very thin ice. "After all, everybody knows that the Federation has plenty of men who are just as honest and well-intentioned and co-operative as anyone here. But you can't run a solar system on gusts of emotion. Would you really hesitate if it came to a showdown between Earth and the Federation?"

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  There was a long pause. Then Jamieson sighed. "I don't know," he answered. "I really don't know." It was a completely frank and honest answer. As far as Sad­ler was concerned, it virtually eliminated Jamieson from his list of suspects.

  The fantastic incident of the searchlight in the Mare Im-brium occurred nearly twenty-four hours later. Sadler heard about it when he joined Wagnall for morning coffee, as he usually did when he was near Administration.

  "Here's something to make you think," said Wagnall as Sadler walked into the secretary's office. "One of the technicians from Electronics was up in the dome just now, admiring the view, when suddenly a beam of light shot up over the horizon. It lasted for about a second, and he says it was a brilliant blue-white. There's no doubt that it came from that place that Wheeler and Jamieson visited. I know that Instrumentation has been having trouble with them, and I've just checked. Their magnetometers were kicked right off scale ten minutes ago, and there's been a severe local 'quake.' "

  "I don't see how a searchlight would do that sort of thing," answered Sadler, genuinely puzzled. Then the full implica­tions of the statement reached him.

  "A beam of light?
" he gasped. "Why, that's impossible. It wouldn't be visible in the vacuum here."

  "Exactly," said Wagnall, obviously enjoying the other's mystification. "You can only see a light beam when it passes through something. And this was really brilliant—almost dazzling. The phrase Williams used was 'it looked like a solid bar.' Do you know what / think that place is ?"

  "No," replied Sadler, wondering how near Wagnall had got to the truth. "I haven't any idea."

  The secretary looked rather bashful, as if trying out a theory of which he was a little ashamed.

  "I think it's some kind of fortress. Oh, I know it sounds fantastic, but when you think about it, you'll see it's the only explanation that fits all the facts."

  Before Sadler could reply, or indeed think of a suitable an­swer, the desk buzzer sounded and a slip of paper dropped out