"Well," said Jamieson after he too had carried out a long scrutiny through the glasses, "someone's spending an awful lot of money."

  "What do you think it is? A mine?"

  "It could be," replied the other, cautious as ever. "Perhaps they've decided to process the ores on the spot, and all their ex­traction plant is in that dome. But that's only a guess—I've cer­tainly never seen anything like it before."

  "We can reach it in an hour, whatever it is. Shall we go over and have a closer look?"

  "I was afraid you were going to say that. I'm not sure it would be a very wise thing. They might insist on us staying."

  "You've been reading too many scare articles. Anyone would think there was a war on and we were a couple of spies. They couldn't detain us—the Observatory knows where we are and the director would raise hell if we didn't get back."

  "I suspect he will when we do, so we might as well get hung for sheep as lambs. Come along—it's easier on the way down."

  "I never said it was hard on the way up," protested Wheeler, not very convincingly. A few minutes later, as he followed Jamieson down the slope, an alarming thought struck him.

  "Do you think they're listening to us? Suppose someone's got a watch on this frequency—they'll have heard every word we've said. After all, we're in direct line of sight."

  "Who's being melodramatic now? No one except the Ob­servatory would be listening on this frequency, and the folks at home can't hear us as there's rather a lot of mountain in the way. Sounds as if you've got a guilty conscience; anyone would think that you'd been using naughty words again."

  This was a reference to an unfortunate episode soon after

  49

  Wheeler's arrival. Since then he had been very conscious of the fact that privacy of speech, which is taken for granted on Earth, is not always available to the wearers of spacesuits, whose every whisper can be heard by anyone within radio range.

  The horizon contracted about them as they descended to ground level, but they had taken careful bearings and knew which way to steer when they were back in Ferdinand. Jamieson was driving with extra caution now, for this was terrain over which he had never previously traveled. It was nearly two hours before the enigmatic dome began to bulge above the skyline, followed a little later by the squat cylinders of the freighters.

  Once again, Wheeler aimed their roof antenna on Earth, and called the Observatory to explain what they had discovered and what they intended to do. He rang off before anyone Could tell them not to do it, reflecting how crazy it was to send a message 800,000 kilometers in order to talk to someone a hundred kilo­meters away. But there was no other way of getting long-dis­tance communication from ground level; everything below the horizon was blocked off by the shielding effect of the Moon. It was true that by using long waves it was sometimes possible to send signals over great distances by reflection from the Moon's very tenuous ionosphere, but this method was too unreliable to be of serious use. For all practical purposes, lunar radio contact had to be on a "line of sight" basis.

  It was very amusing to watch the commotion that their ar­rival had caused. Wheeler thought it resembled nothing so much as an ant heap that had been well stirred with a stick. In a very short time they found themselves surrounded by tractors, moon-dozers, hauling machines, and excited men in spacesuits. They were forced by sheer congestion to bring Ferdinand to a halt.

  "At any moment," said Wheeler, "they'll call out the guards."

  Jamieson failed to be amused.

  "You shouldn't make jokes like that," he chided. "They're apt to be too near the truth."

  "Well, here comes the reception committee. Can you read the lettering on his helmet? SEC. 2, isn't it? 'Section Two,' I sup­pose that means."

  "Perhaps. But SEC. could just as easily stand for Security. Well—it was all your idea. I'm merely the driver."

  50

  At that moment there was a series of peremptory knocks on the outer door of the airlock. Jamieson pressed the button that opened the seal and a moment later the "reception committee" was removing his helmet in the cabin. He was a grizzled, sharp-featured man with a worried expression that looked as though it was permanently built in. It did not appear that he was pleased to see them.

  He regarded Wheeler and Jamieson thoughtfully, while the two astronomers put on their friendliest smiles. "We don't usu­ally get visitors in these parts," he said. "How did you happen to get here?"

  The first sentence, Wheeler thought, was as good an under­statement as he had heard for some time.

  "It's our day off—we're from the Observatory. This is Dr. Jamieson—I'm Wheeler. Astrophysicists, both of us. We knew you were around here, so decided to come and have a look."

  "How did you know?" the other asked sharply. He still had not introduced himself, which would have been bad manners even on Earth and was quite shocking here.

  "As you may have heard," said Wheeler mildly, "we possess one or two rather large telescopes over at the Observatory. And you've been causing us a lot of trouble. I, personally, have had two spectrograms ruined by rocket glare. So can you blame us for being a trifle inquisitive?"

  A slight smile played around their interrogator's lips, and was instantly banished. Nevertheless, the atmosphere seemed to thaw a little.

  "Well, I think it would be best if you come along to the office while we make a few checks. It won't take very long."

  "I beg your pardon? Since when has any part of the Moon been private property?"

  "Sorry, but that's the way it is. Come along, please."

  The two astronomers climbed into their suits and followed through the airlock. Despite his aggressive innocence, Wheeler was beginning to feel a trifle worried. Already he was visualiz­ing all sorts of unpleasant possibilities; and recollections of what he had read about spies, solitary confinement and brick walls at dawn rose up to comfort him.

  They were led to a smoothly fitting door in the curve of the

  51

  great dome, and found themselves inside the space formed by the outer wall and an inner, concentric hemisphere. The two shells, as far as could be seen, were spaced apart by an intricate webbing of some transparent plastic. Even the floor underfoot was made of the same substance. This, Wheeler decided, was all very odd, but he had no time to examine it closely.

  Their uncommunicative guide hurried them along almost at a trot, as if he did not wish them to see more than necessary. They entered the inner dome through a second airlock, where they removed their suits. Wheeler wondered glumly when they would be allowed to retrieve them again.

  The length of the airlock indicated that the inner dome must be of tremendous thickness, and when the door ahead of them opened, both astronomers immediately noticed a familiar smell. It was ozone. Somewhere, not very far away, was high-voltage electrical equipment. There was nothing unduly remarkable about that, but it was another fact to be filed away for future reference.

  The airlock had opened into a small corridor flanked by doors bearing painted numbers and such labels as PRIVATE, TECH­NICAL STAFF ONLY, INFORMATION, STANDBY AIR, EMERGENCY POWER and CENTRAL CONTROL. Neither Wheeler nor Jamieson could deduce much from these notices, but they looked at each other thoughtfully when they were final­ly halted at a door marked SECURITY. Jamieson's expression told Wheeler, as clearly as any words could do "I told you so!"

  After a short pause a "Come In" panel glowed and the door swung automatically open. Ahead lay a perfectly ordinary office dominated by a determined-looking man at a very large desk. The size of the desk was itself a proclamation to the world that money was no object here, and the astronomers contrasted it ruefully with the office equipment to which they were accus­tomed. A teleprinter of unusually complicated design stood on a table in one comer, and the remaining walls were entirely cov­ered by file cabinets.

  "Well," said the security officer, "who are these people?" "Two astronomers from the Observatory over in Plato. They've just dropped in by tractor, and I th
ought you should see them."

  52

  "Most certainly. Your names, please?"

  There followed a tedious quarter of an hour while particulars were carefully noted down and the Observatory was called. That meant, Wheeler thought glumly, that the fat would now be in the fire. Their friends in Signals, who had been logging their progress in case of any accident, would now have to report their absence officially.

  At last their identities were established, and the man at the imposing desk regarded them with some perplexity. Presently his brows cleared and he began to address them.

  "You realize, of course, that you are something of a nuisance. This is the last place we ever expected visitors, otherwise we'd have put up notices telling them to keep off. Needless to say, we have means of detecting any who may turn up, even if they're not sensible enough to drive up openly, as you did.

  "However, here you are and I suppose there's no harm done. You have probably guessed that this is a government project, and one we don't want talked about. I'll have to send you back, but I want you to do two things."

  "What are they?" asked Jamieson suspiciously.

  "I want you to promise not to talk about this visit more than you have to. Your friends will know where you've gone, so you can't keep it a complete secret. Just don't discuss it with them, that's all."

  "Very well," agreed Jamieson. "And the second point?"

  "If anyone persists in questioning you, and shows particular interest in this little adventure of yours—report it at once. That's all. I hope you have a good ride home."

  Back in the tractor, five minutes later, Wheeler was still fuming.

  "Of all the high-handed so-and-sos! He never even offered us a smoke."

  "I rather think," said Jamieson mildly, "that we were lucky to get off so. easily. They meant business."

  "I'd like to know what sort of business. Does that look like a mine to you? And why should anything be going on in a slag-heap like the Mare?"

  "I think it must be a mine. When we drove up, I noticed something that looked very much like drilling machinery on

  53

  the other side of the dome. But it's hard to account for all the cloak-and-dagger nonsense."

  "Unless they've discovered something that they don't want the Federation to know about."

  "In that case we're not likely to find out, either, and might as well stop racking our brains. But to get on to more practical matters—where do we go from here?"

  "Let's stick to our original plan. It may be some time before we have a chance of using Ferdy again, and we might as well make the most of it. Besides, it's always been one of my ambi­tions to see the Sinus Iridum from ground level, as it were."

  "It's a good three hundred kilometers east of here."

  "Yes, but you said yourself it was pretty flat, if we keep away from the mountains. We should be able to manage it in five hours. I'm a good-enough driver now to relieve you when you want a rest."

  "Not over fresh ground—that would be far too risky. But we'll make a compromise. I'll take you as far as the Laplace Promontory, so that you'll have a look into the Bay. And then you can drive home, following the track I've made. Mind you stick to it, too,"

  Wheeler accepted gladly. He had been half afraid that Jamie-son would abandon the trip and sneak back to the Observatory, but decided that he had done his friend an injustice.

  For the next three hours they crawled along the flanks of the Teneriffe Mountains, then struck out across the plain to the Straight Range, that lonely, isolated band of mountains like a faint echo of the mighty Alps. Jamieson drove now with a steady concentration; he was going into new territory and could take no chances. From time to time he pointed out famous land­marks and Wheeler checked them against the photographic chart.

  They stopped for a meal about ten kilometers east of the Straight Range, and investigated more of the boxes which the Observatory kitchen had given them. One corner of the tractor was fitted out as a tiny galley, but they didn't intend to do any real cooking except in an emergency. Neither Wheeler nor Jamieson was a sufficiently good cook to enjoy the prep­aration of meals and this, after all, was a holiday. . . .

  54

  "Sid," began Wheeler abruptly, between mouthfuls of sand­wich, "what do you think about the Federation? You've met more of their people than I have."

  "Yes, and liked them. Pity you weren't here before the last crowd left; we had about a dozen of them at the Observatory studying the telescope mounting. They're thinking of building a fifteen-hundred-centimeter instrument on one of the moons of Saturn, you know."

  "That would be quite a project—I always said we're too close to the sun here. It would certainly get clear of the Zodiacal Light and the other rubbish around the inner planets. But to get back to the argument—did they strike you as likely to start a quarrel with Earth?"

  "It's difficult to say. They were very open and friendly with us, but then we were all scientists together and that helps a lot. It might have been different if we'd been politicians or civil servants."

  "Dammit, we are civil servants! That fellow Sadler was re­minding me of it only the other day."

  "Yes, but at least we're scientific civil servants, which makes quite a difference. I could tell that they didn't care a lot for Earth, though they were too polite to say so. There's no doubt that they're annoyed about the metals allocations; I often heard them complain about it. Their main point is that they have much greater difficulties than we have, in opening up the outer planets, and that Earth wastes half the stuff she uses."

  "Which side do you think is right?"

  "I don't know; it's so hard to get at all the facts. But there are a lot of people on Earth who are afraid of the Federation and don't want to give it any more power. The Federals know that; one day they may grab first and argue afterward."

  Jamieson screwed up the wrappings and tossed them into the waste bin. He glanced at the chronometer, then swung him­self up into the driving seat. "Time to get moving again," he said. "We're falling behind schedule."

  From the Straight Range they swung southeast, and presently the great headland of Promontory Laplace appeared on the skyline. As they rounded it, they came across a disconcerting sight—the battered wreck of a tractor, and beside it a rough

  55

  cairn surmounted by a metal cross. The tractor seemed to have been destroyed by an explosion in its fuel tanks, and was an obsolete model of a type that Wheeler had never seen before. He was not surprised when Jamieson told him it had been there for almost a century; it would still look exactly the same a million years from now.

  As they rolled past the headland, the mighty northern wall of the Sinus Iridum—the Bay of Rainbows—swept into view. Eons ago the Sinus Iridum had been a complete ring mountain— one of the largest walled-plains on the Moon. But the cata­clysm which had formed the Sea of Rains had destroyed the whole of the southern wall, so that only a semicircular bay is now left. Across that bay Promontory Laplace and Promontory Heraclides stare at each other, dreaming of the day when they were linked by mountains four kilometers high. Of those lost mountains, all that now remain are a few ridges and low hil­locks.

  Wheeler was very quiet as the tractor rolled past the great cliffs, which stood like a line of titans full-face toward the Earth. The green light splashing down their flanks revealed every detail of the terraced walls. No one had ever climbed those heights, but one day, Wheeler knew, men would stand upon their summits and stare out in victory across the Bay. It was strange to think that after two hundred years, there was so much of the Moon untrodden by human feet, and so many places that a man must reach with nothing to aid him but his own exertions and skill.

  He remembered his first glimpse of the Sinus Iridum, through the little homemade telescope he had built when he was a boy. It had been nothing more than two small lenses fixed in a cardboard tube, but it had given him more pleasure than the giant instruments of which he was now the master.

  J
amieson swung the tractor round in a great curve, and brought it to a halt facing back toward the west. The line they had trampled through the dust was clearly visible, a road which would remain here forever unless later traffic obliterated it.

  "The end of the line," he said. "You can take over from here. She's all yours until we get to Plato. Then wake me up and I'll take her through the mountains. Good night."

  56

  How he managed it, Wheeler couldn't imagine, but within ten minutes Jamieson was asleep. Perhaps the gentle rocking of the tractor acted as a lullaby, and he wondered how successful he would be in avoiding jolts and jars on the way home. Well, there was only one way to find out. . . . He aimed carefully at the dusty track, and began to retrace the road to Plato.