The optical workshop, where patient craftsmen shaped glass to a fraction of a millionth of an inch, using a technique un­changed for centuries, fascinated him but advanced his search no further. He peered at the interference fringes produced by clashing light waves, and watched them scurry madly back and forth as the heat of his body caused microscopic expansions in blocks of flawless glass. Here art and science met, to achieve perfections unmatched elsewhere in the whole range of human technology. Could there be any clue for him here in this buried factory of lenses, prisms and mirrors? It seemed most improba­ble.

  He was, Sadler thought glumly, rather in the position of a man in a darkened coal cellar, looking for a black cat that might not be there. What was worse, to make the analogy more accurate he would have to be a man who didn't know what a cat looked like, even when he saw one.

  His private discussions with Maclaurin helped him a good deal. The director was still skeptical, but was obviously co­operating to the full if only to get this annoying interloper out of the way. Sadler could question him about any technical aspect of the Observatory's work, though he was careful not to give any hints as to the direction his search was taking him.

  He had now compiled a small dossier for every member of the staff—no mean achievement, even though the factual data had been supplied before he came to the Observatory. For most of his subjects, a single sheet of paper sufficed, but for some he

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  had accumulated several pages of cryptic notes. The facts he was sure of he wrote in ink; the speculations were in pencil so that they could be modified when necessary. Some of these speculations were very wild and frequently libelous, and Sadler often felt very ashamed of them. It was hard, for example, to accept a drink from someone whom you had noted down as possibly susceptible to bribes owing to the cost of maintaining an expensive mistress in Central City. . . .

  This particular suspect had been one of the engineers in Construction. Sadler had soon ruled him out as a likely candi­date for blackmail, since far from concealing the situation the victim was always complaining bitterly about his inamorata's extravagances. He had even warned Sadler against incurring similar liabilities.

  The filing system was divided into three parts. Section A contained the names of the ten or so men Sadler considered the most probable suspects, though there was not one against whom he had any real evidence. Some were down simply because they had the greatest opportunity for passing out information if they wished to do so. Wagnall was one of these; Sadler was practically certain that the secretary was innocent, but kept him on the list to be on the safe side.

  Several others were listed because they had close relatives in the Federation, or because they were too openly critical of Earth. Sadler did not really imagine that a well-trained spy would risk arousing suspicion by behaving in this way, but he had to be on the watch for the enthusiastic amateur who could be just as dangerous. The records of atomic espionage during the Second World War had been very instructive in this respect, and Sadler had studied them with great care.

  Another name on List A was that of Jenkins, the chief store­keeper. This was only the most tenuous of hunches, and all attempts by Sadler to follow it up had been unsuccessful. Jenkins seemed to be a somewhat morose individual, who re­sented interference and was not very popular with the rest of the staff. Getting anything out of him in the way of equipment was supposed to be the most difficult job on the Moon. This, of course, might merely mean that he was a good representative of his proverbially tenacious tribe.

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  There remained that interesting couple Jamieson and Wheeler, who between them did a great deal to enliven the Observatory scene. Their drive out into the Mare Imbrium had been a fairly typical exploit, and had followed, so Sadler was assured, the pattern of earlier adventures.

  Wheeler was always the leading spirit. His trouble—if it was a trouble—was that he had too much energy and too many interests. He was not yet thirty; one day, perhaps, age and re­sponsibility would mellow him, but so far neither had had much opportunity. It was too easy to dismiss him as a case of arrested development, as a college boy who had failed to grow up. He had a first-rate mind, and never did anything that was really foolish. Though there were many people who did not like him, particularly after they had been the victims of one of his practical jokes, there was nobody who wished him any harm. He moved unscathed through the little jungle of Ob­servatory politics, and had the abiding virtues of complete honesty and forthrightness. One always knew what he was thinking, and it was never necessary to ask him for his opinion. He gave it first.

  Jamieson was a very different character, and presumably it was the contrast in their personalities which drew these two men together. He was older than Wheeler by a couple of years, and was regarded as a sobering influence on his younger com­panion. Sadler doubted this; as far as he could judge, Jamieson's presence had never made any difference in his friend's behavior. He had mentioned this to Wagnall, who had thought for a while and said, "Yes, but think how much worse Con would be if Sid wasn't there to keep an eye on him."

  Certainly Jamieson was far more stable and much harder to get to know. He was not as brilliant as Wheeler and would probably never make any shattering discoveries, but he would be one of those reliable, sound men who do the essential tidying up after the geniuses have broken through into new territory.

  Scientifically reliable—yes. Politically reliable—that was an­other matter. Sadler had tried to sound him, without making it too obvious, but so far with little success. Jamieson seemed more interested in his work and his hobby—the painting of lunar landscapes—than in politics. During his term at the

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  Observatory he had built up a small art gallery, and whenever he had the chance he would go out in a spacesuit carrying easel and special paints made from low-vapor-pressure oils. It had taken him a good deal of experimenting to find pigments that could be used in a vacuum, and Sadler frankly doubted that the results were worth the trouble. He thought he knew enough about art to decide that Jamieson had more enthusiasm than talent, and Wheeler shared this point of view. "They say that Sid's pictures grow on you after a while," he had confided to Sadler. "Personally, I can think of no more horrible fate."

  Sadler's List B contained the names of everybody else in the Observatory who looked intelligent enough to be a spy. It was depressingly long, and from time to time he went through it trying to transfer people to List A or—better still—to the third and final list of those who were completely clear of suspicion. As he sat in his little cubicle, shuffling his sheets and trying to put himself into the places of the men he was watching, Sadler sometimes felt that he was playing an intricate game, in which most of the rules were flexible and all the players unknown. It was a deadly game, the moves were taking place at accelerating speed—and upon its outcome might depend the future of the human race.

  Chapter X

  the voice that came from the speaker was deep, cultured and sincere. It had been traveling across space for many minutes, beamed through the clouds of Venus along the two-hundred-million-kilometer link to Earth, thea relayed again from Earth to Moon. After that immense journey, it was still clear and clean, almost untouched by interference or distortion.

  "The situation here has hardened since my last commen­tary. No one in official circles will express any opinion, but the press and radio are not so reticent. I flew in from Hesperus this morning, and the three hours I've been here are quite long enough for me to gauge public opinion.

  "I must speak bluntly, even if I have to upset the people

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  back home. Earth isn't very popular here. The phrase 'dog in the manger' gets bandied around quite a lot. Your own sup­ply difficulties are recognized, but it's felt that the frontier planets are short of necessities while Earth wastes much of its resources on trivial luxuries. I'll give you an example. Yes­terday the news came in that the Mercury outpost has just lost five men through a faulty heat-ex
change unit in one of the domes. The temperature control failed and the lava got them —not a very nice death. If the manufacturer had not been short of titanium, this wouldn't have happened.

  "Of course, it's not fair to blame Earth for this. But it's unfortunate that only a week ago you cut the titanium quota again, and the interested parties here are seeing that the pub­lic doesn't forget it. I can't be more specific than that, because I don't want to be cut off, but you'll know who I mean.

  "I don't believe that the situation will get any worse un­less some new factor enters the picture. But suppose—and here I want to make it quite clear that I'm only considering a hypothetical case—suppose Earth were to locate new sup­plies of the heavy metals. In the still-unexplored ocean depths, for instance. Or even on the Moon, despite the disappoint­ments it's given in the past.

  "If this happens, and Earth tries to keep its discovery to itself, the consequences may be serious. It's all very well to say that Earth would be within its rights. Legal arguments don't carry much weight when you're fighting thousand-at­mosphere pressures on Jupiter, or trying to thaw out the frozen moons of Saturn. Don't forget, as you enjoy your mild spring days and peaceful summer evenings, how lucky you are to live in. the temperate region of the solar system, where the air never freezes and the rocks never melt. . . .

  "What is the Federation likely to do if such a situation arises? If I knew, I couldn't tell you. I can only make some guesses. To talk about war, in the old-fashioned sense, seems absurd to me. Either side could inflict heavy damage on the other, but any real trial of strength could not possibly be con­clusive. Earth has too many resources, even though they are dangerously concentrated. And she owns most of the ships in the solar system.

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  "The Federation has the advantage of dispersion. How can Earth carry out a simultaneous fight against half-a-dozen planets and moons, poorly equipped though they may be? The supply problem would be completely hopeless.

  "If, which heaven forbid, it should come to violence, we may see sudden raids on strategic points by specially equipped vessels which will make an attack and then retreat into space. Any talk of interplanetary invasion is pure fantasy. Earth cer­tainly has no wish to take over the planets. And the Federa­tion, even if it wanted to enforce its will on Earth, has neither the men nor the ships for a full-scale assault. As I see it, the immediate danger is that something like a duel may take place —where and how is anyone's guess—as one side attempts to impress the other with its strength. But I would warn any who may be thinking of a limited, gentlemanly war that wars were seldom limited, and never gentlemanly. Good-by, Earth—this is Roderick Beynon, speaking to you from Venus."

  Someone reached out and turned off the set, but at first no­body seemed inclined to start the inevitable discussion. Then Jansen, from Power, said admiringly:

  "Beynon's got guts, you must admit. He wasn't pulling his punches. I'm surprised they let him make that broadcast."

  "I thought he talked good sense," remarked Mays. The High Priest of Computing had a slow, measured style of de­livery that contrasted quaintly with the lightning speed of his machines.

  "Whose side are you on?" someone asked suspiciously.

  "Oh, I'm a friendly neutral."

  "But Earth pays your salary. Which side would you sup­port if there was a showdown?"

  "Well that would depend on the circumstances. I'd like to support Earth. But I reserve the right to make up my own mind. Whoever it was who said 'My planet right or wrong' was a damned fool. I'd be for Earth if it was right, and would probably give it the benefit of the doubt in a borderline case. But I'd not support it if I felt its cause was definitely wrong."

  There was a long silence while everyone thought this over. Sadler had been watching Mays intently while the mathema­tician was speaking. Everyone, he knew, respected Mays's

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  honesty and logic. A man who was actively working against Earth would never have expressed himself as forthrightly as this. Sadler wondered if Mays would have spoken any dif­ferently had he known that a counter-intelligence man was sitting within two meters of him. He did not believe that he would have altered a word.

  "But, blast it," said the chief engineer, who as usual was blocking the synthetic fire, "there's no question of right and wrong here. Anything found on Earth or Moon belongs to us, to do with as we like."

  "Certainly, but don't forget we've been falling back on our quota deliveries, as Beynon said. The Federation has been relying on them for its programs. If we repudiate our agree­ments because we haven't got the stuff ourselves, that's one thing. But it's a very different matter if we have got it and are just holding the Federation up for ransom."

  "Why should we do any such thing?"

  It was Jamieson, unexpectedly enough, who answered this. "Fear," he said. "Our politicians are frightened of the Federa­tion. They know it already has more brains, and one day it may have more power. Then Earth will be a back number."

  Before anyone could challenge him on this, Czuikov from the Electronics Lab started a fresh hare.

  "I've been thinking," he said, "about that broadcast we've just heard. We know that Beynon's a pretty honest man, but after all he was broadcasting from Venus, with their permis­sion. There may be more in that talk of his than meets the ear."

  "What do you mean?"

  "He may be putting across their propaganda. Not con­sciously, perhaps; they may have primed him to say what they want us to hear. That talk about raids, for instance. Perhaps it's intended to scare us."

  "That's an interesting idea. What do you think, Sadler? You're the last to come up from Earth."

  This frontal attack took Sadler rather by surprise, but he dexterously tossed the ball back.

  "I don't think Earth can be frightened as easily as that. But the passage that interested me was his reference to pos-

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  sible new supplies on the Moon. It looks as if rumors are be­ginning to float around."

  This was a calculated indiscretion on Sadler's part. It was not so very indiscreet, however, for there was no one in the Observatory who did not know (a) that Wheeler and Jamie-son had stumbled on some unusual government project in the Mare Imbrium, and (b) that they had been ordered not to talk about it. Sadler was particularly anxious to see what their reactions would be.

  Jamieson assumed a look of puzzled innocence, but Wheeler did not hesitate to rise to the bait.

  "What do you expect?" he said. "Half the Moon must have seen those ships coming down in the Mare. And there must be hundreds of workmen there. They can't all have come from Earth—they'll be going into Central City and talking to their girl friends when they've had a few drinks too many."

  How right you are, thought Sadler, and what a headache that little problem was giving Security. . . .

  "Anyway," continued Wheeler, "I've got an open mind on the subject. They can do what they like out there as long as they don't interfere with me. You can't tell a thing from the out­side of the place, except that it's costing the poor taxpayer an awful lot of money."

  There was a nervous cough from a mild little man from Instrumentation, where only that morning Sadler had spent a boring couple of hours looking at cosmic-ray telescopes, mag­netometers, seismographs, molecular-resonance clocks, and batteries of other devices which were surely storing informa­tion more rapidly than anyone would ever be able to analyze it.

  "I don't know about them interfering with you, but they've been playing hell with me."

  "What do you mean?" everyone asked simultaneously.

  "I had a look at the magnetic-field-strength meters half an hour ago. Usually the field here is pretty constant, except when there's a storm around, and we always know when to expect those. But something odd's going on at the moment. The field keeps hopping up and down—not very much, a few microgauss —and I'm sure it's artificial. I've checked all the equipment in the Observatory, and everyone swears they're not mucking

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r />   around with magnets. I wondered if our secretive friends out in the Mare were responsible, and just on the chance, I had a look at the other instruments. I didn't find anything until I came to the seismographs. We've got a telemetering one down by the south wall of the crater, you know, and it had been knocked all over the place. Some of the kinks looked like blast­ing; I'm always picking that up from Hyginus and the other mines. But there were also some most peculiar jitters of the trace that were almost synchronized with the magnetic pulses. Allowing for the time-lag through the rock, the distance check­ed up well. There's no doubt where it comes from."

  "An interesting piece of research," Jamieson remarked, "but what does it add up to?"

  "There are probably a good many interpretations. But I'd say that out there in the Mare Imbrium someone is generating a colossal magnetic field, in pulses lasting about a second at a time."