"We did not plan to," Barlennan a.s.sured him, with glee that he managed to conceal. "We thank you for the advice and information." He gave the order to hoist the anchor, and for the first time Reejaaren noticed the canoe, now trailing once more at the end of its towrope and loaded with food.

"I should have noticed that before," the interpreter said. "I would never have doubted your story of coming from the south. How did you get that from the natives?" In the answer to this question Barlennan made his first serious mistake in dealing with the islander.

"Oh, we brought that with us; we frequently use them for carrying extra supplies. You will notice that its shape makes it easy to tow." He had picked up his elementary notions of streamlining from Lackland not too long after acquiring the canoe.

"Oh, you developed that craft in your country too?" the interpreter asked curiously. "That is interesting; I had never seen one in the south. May I examine it, or do you not have time? We have never bothered to use them ourselves." Barlennan hesitated, suspecting this last statement to be a maneuver of the precise sort he himself had been employing; but he saw no harm in complying, since Reejaaren could learn nothing more from a close examination than he could from where he was. After all, it was the canoe's shape that was important, and anyone could see that. He allowed the Bree to drift closer insh.o.r.e, pulled the canoe to him with the towrope, and gave it a push toward the waiting islander. Reejaaren plunged into the bay and swam out to the little vessel when it ran aground, in a few inches of liquid. The front part of his body arched upward to look into the canoe; powerful pincer-tipped arms poked at the sides. These were of ordinary wood, and yielded springily to the pressure; and as they did so the islander gave a hoot of alarm that brought the four gliders in the air swinging toward the Bree and the sh.o.r.e forces up to full alertness.

"Spies!" he shrieked. "Bring your ship aground at once, Bartennan-if that is your real name. You are a good liar, but you have lied yourself into prison this time!"

14: THE TROUBLE WITH HOLLOW BOATS.

Barlennan had been told at various times during his formative years that he was someday pretty sure to talk himself into more trouble than he could talk himself out of. At various later times during his career this prediction had come alarmingly close to fulfillment, and each time he had resolved to be more careful in the future with his tongue. He felt the same way now, together with an injured feeling arising from the fact that he did not yet know just what he had said that had betrayed his mendacity to the islander. He did not have time to theorize over it, either; something in the line of action was called for, the quicker the better. Reejaaren had already howled orders to the glider crews to pin the Bree to the bottom if she made a move toward the open sea, and the catapults on sh.o.r.e were launching more of the machines to reinforce those already aloft. The wind was coming from the sea at a sufficient angle to be lifted as it struck the far wall of the fiord, so the flyers could remain aloft as long as necessary. Barlennan had learned from the Earthmen that they probably could not climb very high-high enough for effective missile dropping-under the thrust of the updrafts from ocean waves; but he was a long way from the open sea where they would have to depend on such currents. He had already had a chance to observe their accuracy, and dismissed at once any idea of trusting to his dodging ability to save his ship.

As so frequently happened, the action was performed by a crew member while he was debating the best course. Dondragmer s.n.a.t.c.hed up the crossbow that had been given them by Reejaaren, nocked a bolt, and c.o.c.ked the weapon with a speed that showed he could not have been completely absorbed in his hoist project at all times. Swinging the weapon sh.o.r.eward, he rested it on its single support leg and covered the interpreter with the point.

"Hold on, Reejaaren; you're moving in the wrong direction." The islander stopped on his way out of the bay, liquid dripping from his long body, and doubled his front half back toward the ship to see what the mate meant. He saw clearly enough, but seemed for a moment undecided about the proper course of action.

"If you want to a.s.sume I'll probably miss because I've never handled one of these things, go right ahead. I'd like to find out myself. If you don't start coming this way in an awfully short time, though, it will be just as though you had tried to escape. Move!" The last word was issued in a barking roar that removed much of the interpreter's indecision. He apparently was not quite sure of the mate's incompetence; he continued the doubling movement, re-entered the bay, and swam out to the Bree. If he thought of concealing himself by submerging during the process, he evidently lacked the courage to try it. As he well knew, the methane was only a few inches deep even at the ship's location, and would hardly protect him from a bolt hurled with force enough to penetrate three inches of wood after a forty-yard trajectory under seven gravities. He did not think of it in those terms, of course, but he knew very well what those projectiles could do.

He clambered aboard, shaking with rage and fear together.

"Do you think this will save you?" he asked. "You have simply made things worse for yourselves. The gliders will drop in any event if you try to move, whether I am aboard or not."

"You will order them not to."

"They will obey no order I give while I am obviously in your power; you should know that if you have any sort of fighting force."

"I've never had much to do with soldiers," Barlennan replied. He had recovered the initiative, as he usually did once things had started in a definite direction. "However, I'll believe you for the time being. We'll just have to hold you here until some understanding is reached concerning this nonsense about our going ash.o.r.e-unless we can take care of those gliders of yours in the meantime. It's a pity we didn't bring some more modern armament into this backward area."

"You can stop that nonsense now," returned the captive. "You have nothing more than the rest of the savages of the south. I'll admit you fooled us for a time, but you betrayed yourself a moment ago."

"And what did I say that made you think I'd been lying?"

"I see no reason to tell you. The fact that you don't yet know just proves my point. It would have been better for you if you hadn't fooled us so completely; then we'd have been more careful with secret information, and you wouldn't have learned enough to make your disposal necessary."

"And if you hadn't made that last remark, you might have talked us into surrendering," cut in Dondragmer, "though I admit it's not likely. Captain, I'll bet that what you slipped up on was what I've been telling you all along. It's too late to do anything about that now, though. The question is how to get rid of these pesky gliders; I don't see any surface craft to worry about, and the folks on sh.o.r.e have only the crossbows from the gliders that were on the ground. I imagine they'll leave things to the aircraft for the time being." He shifted to English. "Do you remember anything we heard from the Flyers that would help us get rid of these pesky machines?" Barlennan mentioned their probable alt.i.tude limitations over open sea, but neither could see how that helped at the moment.

"We might use the crossbow on them." Barlennan made the suggestion in his own language, and Reejaaren sneered openly. Krendoranic, the munitions officer of the Bree, who like the rest of the crew had been listening eagerly, was less contemptuous.

"Let's do that," he cut in sharply. "There's been something I've wanted to try ever since we were at that river village."

"What?"

"I don't think you'd want me to talk about it with our friend listening. We'll show him instead, if you are willing." Barlennan hesitated a moment, then gave consent.

Barlennan looked a trifle worried as Krendoranic opened one of the flame lockers, but the officer knew what he was doing. He removed a small bundle already wrapped in lightproof material, thus giving evidence of at least some of his occupation during the nights since they had left the village of the river-dwellers.

The bundle was roughly spherical, and evidently designed to be thrown by arm-power; like everyone else, Krendoranic had been greatly impressed by the possibilities of this new art of throwing. Now he was extending his idea even further, however.

He took the bundle and lashed it firmly to one of the crossbow bolts, wrapping a layer of fabric around bundle and shaft and tying it at either end as securely as possible. Then he placed the bolt in the weapon. He had, as a matter of duty, familiarized himself with the device during the brief trip downstream and the rea.s.sembly of the Bree, and had no doubt about his ability to hit a sitting target at a reasonable distance; he was somewhat less sure about moving objects, but at least the gliders could only turn rapidly if they banked sharply, and that would give him warning.

At his order, one of the sailors who formed part of his flamethrower crew moved up beside him with the igniting device, and waited. Then to the intense annoyance of the watching Earthmen, he crawled to the nearest of the radios and set the leg of the bow on top of it to steady himself and the weapon in an upward position. This effectively prevented the human beings from seeing what went on, since the radios were set to look outward from a central point and neither of the others commanded a view of the first.

As it happened, the gliders were still making relatively low pa.s.ses, some fifty feet above the bay, and coming directly over the Bree on what could on an instant's notice become bomb runs; so a much less experienced marksman than the munitions officer could hardly have missed. He barked a command to his a.s.sistant as one of the machines approached, and began to lead it carefully. The moment he was sure of his aim, he gave a command of execution and the a.s.sistant touched the igniter to the bundle on the slowly rising arrow point. As it caught, Krendoranic's pincer tightened on the trigger and a line of smoke marked the trail of the missile from the bow.

Krendoranic and his a.s.sistant ducked wildly back to deck level and rolled upwind to get away from the smoke released at the start; sailors to leeward of the release point leaped to the other side. By the time they felt safe, the air action was almost over.

The bolt had come as close as possible to missing entirely; the marksman had underestimated his target's speed. It had struck about as far aft on the main fuselage as it could, and the bundle of chlorine powder was blazing furiously. The cloud of flame was spreading to the rear of the glider and leaving a trail of smoke that the following machines made no effort to avoid. The crew of the target ship escaped the effects of the vapor, but in a matter of seconds their tail controls burned away. The glider's nose dropped and it fluttered down to the beach, pilot and crew leaping free just before it touched. The two aircraft which had flown into the smoke also went out of control as the hydrogen chloride fumes incapacitated their personnel, and both settled into the bay. All in all, it was one of the great anti-aircraft shots in history.

Barlennan did not wait for the last of the victims to crash, but ordered the sails set. The wind was very much against him, but there was depth enough for the centerboards, and he began to tack out of the fiord. For a moment it looked as though the sh.o.r.e personnel were about to turn their own crossbows on the ship, but Krendoranic had loaded another of his frightful missiles and aimed it toward the beach, and the mere threat sent them scampering for safety-upwind; they were sensible beings for the most part.

Reejaaren had watched in silence, while his bodily att.i.tude betrayed blank dismay. Gliders were still in the air, and some were climbing as though they might attempt runs from a higher alt.i.tude; but he knew perfectly well that the Bree was relatively safe from any such attempt, excellent though his aimers were. One of the gliders did make a run at about three hundred feet, but another trail of smoke whizzing past spoiled his aim badly and no further attempts were made. The machines drifted in wide circles well out of range while the Bree slipped on down the fiord to the sea.

"What in blazes has been happening, Barl?" Lackland, unable to restrain himself longer, decided it was safe to speak as the crowd on sh.o.r.e dwindled with distance. "I haven't been b.u.t.ting in for fear the radios might spoil some of your plans, but please let us know what you've been doing."

Barlennan gave a brief resume of the events of the last few hundred days, filling in for the most part the conversations his watchers had been unable to follow. The account lasted through the minutes of darkness, and sunrise found the ship almost at the mouth of the fiord. The interpreter had listened with shocked dismay to the conversation between captain and radio; he a.s.sumed, with much justice, that the former was reporting the results of his spying to his superiors, though he could not imagine how it was being done. With the coming of sunrise he asked to be put ash.o.r.e in a tone completely different from any he had used before; and Barlennan, taking pity on a creature who had probably never asked for a favor in his life from a member of another nation, let him go overboard from the moving vessel fifty yards from the beach. Lackland saw the islander dive into the sea with some relief; he knew Barlennan quite well, but had not been sure just what course of action he would consider proper under the circ.u.mstances.

"Barl," he said after a few moments' silence, "do you suppose you could keep out of trouble for a few weeks, until we get our nerves and digestions back up here? Every time the Bree is held up, everyone on this moon ages about ten years."

"Just who got me into this trouble?" retorted the Mesklinite. "If I hadn't been advised to seek shelter from a certain storm-which it turned out I could have weathered better on the open sea-I'd certainly never have met these glider makers. I can't say that I'm very sorry I did, myself; I learned a lot, and I know at least some of your friends wouldn't have missed the show for anything. From my point of view this trip has been rather dull so far; the few encounters we have had have all terminated very tamely, and with a surprising amount of profit."

"Just which do you like best, anyway: adventure or cash?"

"Well-I'm not sure. Every now and then I let myself in for something just because it looks interesting; but I'm much happier in the end if I make something out of it."

"Then please concentrate on what you're making out of this trip. If it will help you any to do that, we'll collect a hundred or a thousand shiploads of those spices you just got rid of and store them for you where the Bree wintered; it would still pay us, if you'll get that information we need."

"Thanks, I expect to make profit enough. You'd take all the fun out of life."

"I was afraid you'd feel that way. All right, I can't order you around, but please remember what this means to us."

Barlennan agreed, more or less sincerely, and swung his ship once more southward. For some days the island they had left was visible behind them, and often they had to change course to avoid others. Several times they saw gliders skimming the waves on the way from one island to another, but these always gave the ship a wide berth. Evidently news spread rapidly among these people. Eventually the last visible bit of land slipped below the horizon, and the human beings said that there was no more ahead-good fixes could once more be obtained with the weather in its present clear state.

At about forty-gravity lat.i.tude they directed the ship on a more Southeasterly course to avoid the land ma.s.s which, as Reejaaren had said, swung far to the east ahead of her. Actually the ship was following a relatively narrow pa.s.sage between two major seas, but the strait was far too wide for that fact to be noticeable from shipboard.

One minor accident occurred some distance into the new sea. At around sixty gravities the canoe, still following faithfully at the end of its towrope, began to settle visibly in the sea. While Dondragmer put on his best "I told you so" expression and remained silent, the little vessel was pulled up to the ship's stern and examined. There was quite a bit of methane in the bottom, but when she was unloaded and pulled aboard for examination no leak was visible. Barlennan concluded that spray was responsible, though the liquid was much clearer than the ocean itself. He put the canoe back in the sea and replaced its load, but detailed a sailor to inspect every few days and bail when necessary. This proved adequate for many days; the canoe floated as high as ever when freshly emptied, but the rate of leakage grew constantly greater. Twice more she was pulled aboard for inspection without result; Lackland, consulted by radio, could offer no explanation. He suggested that the wood might be porous, but in that case the leaking should have been present from the beginning.

The situation reached a climax at about two hundred gravities, with more than a third of the sea journey behind them. The minutes of daylight were longer now as spring progressed and the Bree moved ever farther from her sun, and the sailors were relaxing accordingly. The individual who had the bailing job was not, therefore, very attentive as he pulled the canoe up the stern rafts and climbed over its gunwale. He was aroused immediately thereafter. The canoe, of course, settled a trifle as he entered; and as it did so, the springy wood of the sides gave a little. As the sides collapsed, it sank a little farther-and the sides yielded more-and it sank yet farther- Like any feedback reaction, this one went to completion in a remarkably short time. The sailor barely had time to feel the side of the canoe pressing inward when the whole vessel went under and the outside pressure was relieved. Enough of the cargo was denser than methane to keep the canoe sinking, and the sailor found himself swimming where he had expected to be riding. The canoe itself settled to the end of its towrope, slowing the Bree with a jerk that brought the entire crew to full alertness.

The sailor climbed back into the Bree, explaining what had happened as he did so. All the crew whose duties did not keep them elsewhere rushed to the stern, and presently the rope was hauled in with the swamped canoe at the end of it. With some effort, the canoe and such of its load as had been adequately lashed down were hauled aboard, and one of the sets turned to view it. The object was not very informative; the tremendous resilience of the wood had resulted in its recovering completely even from this flattening, and the canoe had resumed its original shape, still without leaks. This last fact was established after it had once more been unloaded. Lackland, looking it over, shook his head and offered no explanation. "Tell me just what happened-what everyone who saw anything at all did see."

The Mesklinites complied, Barlennan translating the stories of the crewman who had been involved and the few others who had seen the event in any detail. It was the first, of course, that provided the important bit of information.

"Good Earth!" Lackland muttered, half aloud. "What's the use of a high school education if you can't recall it when needed later on? Pressure in a liquid corresponds to the weight of liquid above the point in question-and even methane under a couple of hundred gravities weighs a good deal per vertical inch. That wood's not much thicker than paper, either; a wonder it held so long." Barlennan interrupted this rather uninformative monologue with a request for information.

"I gather you now know what happened," he said. "Could you please make it clear to us?"

Lackland made an honest effort, but was only partly successful. The concept of pressure, in a quant.i.tative sense, defeats a certain number of students in every high school cla.s.s.

Barlennan did get the idea that the deeper one went into the sea the greater was the crushing force, and that the rate of increase with depth went up along with gravity; but he did not connect this force with others such as wind, or even the distress he himself had experienced when he submerged too rapidly in swimming.

The main point, of course, was that any floating object had to have some part of itself under the surface, and that sooner or later that part was going to be crushed if it was hollow. He avoided Dondragmer's eye as this conclusion was reached in his conversation with Lackland, and was not comforted when the mate pointed out that this was undoubtedly where he had betrayed his falsehood when talking to Reejaaren. Hollow ships used by his own people, indeed! The islanders must have learned the futility of that in the far south long since.

The gear that had been in the canoe was stowed on deck, and the voyage continued. Barlennan could not bring himself to part with the now useless little vessel, though it took up a good deal of s.p.a.ce. He disguised its uselessness thinly by packing it with food supplies which could not have been heaped so high without the sides of the canoe to retain them. Dondragmer pointed out that it was reducing the ship's flexibility by extending the length of two rafts, but the captain did not let this fact worry him.

Time pa.s.sed as it had before, first hundreds and then thousands of days. To the Mesklinites, long-lived by nature, its pa.s.sage meant little; to the Earthmen the voyage gradually became a thing of boredom, part of the regular routine of life. They watched and talked to the captain as the line on the globe slowly lengthened; measured and computed to determine his position and best course when he asked them to; taught English to or tried to learn a Mesklinite language from sailors who sometimes also grew bored; in short, waited, worked where possible, and killed time as four Earthly months-nine thousand four hundred and some odd Mesklinite days-pa.s.sed. Gravity increased from the hundred and ninety or so at the lat.i.tude where the canoe had sunk to four hundred, and then to six, and then further, as indicated by the wooden spring balance that was the Bree's lat.i.tude gauge. The days grew longer and the nights shorter until at last the sun rode completely around the sky without touching the horizon, though it dipped toward it in the south. The sun itself seemed shrunken to the men who had grown used to it during the brief time of Mesklin's perihelion pa.s.sage. The horizon, seen from the Brre's deck through the vision sets, was above the ship all around, as Barlennan had so patiently explained to Lackland months before; and he listened tolerantly when the men a.s.sured him it was an optical illusion. The land that finally appeared ahead was obviously above them too; how could an illusion turn out to be correct? The land was really there. This was proved when they reached it; for reach it they did, at the mouth of a vast bay that stretched on to the south for some two thousand miles, half the remaining distance to the grounded rocket. Up the bay they sailed, more slowly as it finally narrowed to the dimensions of a regular estuary and they had to tack instead of seeking favorable winds with the Flyers' help, and finally to the river at its head. Up this they went too, no longer sailing except at rare, favorable intervals; for the current against the blunt faces of the rafts was more than the sails could usually overcome, broad as the river still was. They towed instead, a watch at a time going ash.o.r.e with ropes and pulling; for in this gravity even a single Mesklinite had a respectable amount of traction. More weeks, while the Earthmen lost their boredom and tension mounted in the Toorey station. The goal was almost in sight, and hopes ran high.

And they were dashed, as they had been for a moment months before when Lackland's tank reached the end of its journey. The reason was much the same; but this time the Bree and its crew were at the bottom of a cliff, not the top. The cliff itself was three hundred feet high, not sixty; and in nearly seven hundred gravities climbing, jumping and other rapid means of travel which had been so freely indulged at the distant Rim were utter impossibilities for the powerful little monsters who manned the ship.

The rocket was fifty miles away in horizontal distance; in vertical, it was the equivalent, for a human being, of a climb of nearly thirty-five-up a sheer rock wall.

15: HIGH GROUND.

The change of mind that had so affected the Bree's crew was not temporary; the unreasoning, conditioned fear of height that had grown with them from birth was gone. They still, however had normal reasoning power; and in this part of their planet a fall of as much as half a body's length was nearly certain to be fatal even to their tough organisms. Changed as they were, most of them felt uneasy as they moored the Bree to the riverbank only a few rods from the towering cliff that barred them from the grounded rocket.

The Earthmen, watching in silence, tried futilely to think of a way up the barrier. No rocket that the expedition possessed could have lifted itself against even a fraction of Mesklin's gravity; the only one that had ever been built able to do so was already aground on the planet. Even had the craft been capable, no human or qualified non-human pilot could have lived in the neighborhood; the only beings able to do that could no more be taught to fly a rocket than a Bushman s.n.a.t.c.hed straight from the jungle.

"The journey simply isn't as nearly over as we thought." Rosten, called to the screen room, a.n.a.lyzed the situation rapidly. "There should be some way to the plateau or farther slope-whichever is present-of that cliff. I'll admit there seems to be no way Barlennan and his people can get up; but there seems to be nothing preventing their going around." Lackland relayed this suggestion to the captain.

"That is true," the Mesklinite replied. "There are, however, a number of difficulties. It is already getting harder to procure food from the river; we are very far from the sea. Also, we have no longer any idea of how far we may have to travel, and that makes planning for food and all other considerations nearly impossible. Have you prepared, or can you prepare, maps with sufficient detail to let us plan our course intelligently?"

"Good point. I'll see what can be done." Lackland turned from the microphone to encounter several worried frowns. "What's the matter? Can't we make a photographic map as we did of the equatorial regions?"

"Certainly," Rosten replied. "A map can be made, possibly with a lot of detail; but it's going to be difficult. At the equator a rocket could hold above a given point, at circular velocity, only six hundred miles from the surface-right at the inner edge of the ring. Here circular velocity won't be enough, even if we could use it conveniently. We'd have to use a hyperbolic orbit of some sort to get short-range pictures without impossible fuel consumption; and that would mean speeds relative to the surface of several hundred miles a second. You can see what sort of pictures that would mean. It looks as though the shots will have to be taken with long-focus lenses, at extremely long range; and we can only hope that the detail will suffice for Barlennan's needs."

"I hadn't thought of that," admitted Lackland. "We can do it, though; and I don't see any alternative in any case. I suppose Barlennan could explore blind, but it would be asking a lot of him."

"Right. We'll launch one of the rockets and get to work." Lackland gave the substance of this conversation to Barlennan, who replied that he would stay where he was until the information he needed was obtained.

"I could either go on upstream, following the cliff around to the right, or leave the ship and the river and follow to the left. Since I don't know which is best from the point of view of distance, we'll wait. I'd rather go upstream, of course; carrying food and radios will be no joke otherwise."

"All right. How is your food situation? You said something about its being hard to get that far from the ocean."

"It's scarcer, but the place is no desert. We'll get along for a time at least. If we ever have to go overland we may miss you and your gun, though. This crossbow has been nothing but a museum piece for nine tenths of the trip."

"Why do you keep the bow?"

"For just that reason-it's a good museum piece, and museums pay good prices. No one at home has ever seen, or as far as I know even dreamed of, a weapon that works by throwing things. You couldn't spare one of your guns, could you? It needn't work, for that purpose."

Lackland laughed. "I'm afraid not; we have only one. We don't expect to need it, but I don't see how we could explain giving it away." Barlennan gave the equivalent of an understanding nod, and turned back to his own duties. He had much to bring up to date on the bowl that was his equivalent of a globe; the Earthmen, throughout the trip, had been giving him bearing and distance to land in all directions, so he was able to get most of the sh.o.r.es of the two seas he had crossed onto the concave map.

It was also necessary to see to the food question; it was not, as he had told Lackland, really pressing, but more work with the nets was going to be necessary from now on. The river itself, now about two hundred yards wide, appeared to contain fish enough for their present needs, but the land was much less promising. Stony and bare, it ran a few yards from one bank of the stream to end abruptly against the foot of the cliff; from the other, a series of low hills succeeded each other for mile after mile, presumably far beyond the distant horizon. The rock of the escarpment's face was polished gla.s.s-smooth, as sometimes happens even on Earth to the rocks at the sliding edges of a fault. Climbing it, even on Earth, would have required the equipment and body weight of a By (on Mesklin, the fly would have weighed too much). Vegetation was present, but not in any great amount, and in the first fifty days of their stay no member of the Bree's crew saw any trace of land animal life. Occasionally someone thought he saw motion, but each time it turned out to be shadows cast by the whirling sun, now hidden from them only by its periodic trips beyond the cliff. They were so near the south pole that there was no visible change in the sun's alt.i.tude during the day.

For the Earthmen, the time was a little more active. Four of the expedition, including Lackland, manned the rocket and dropped planetward from the rapidly moving moon. From their takeoff point the world looked rather like a pie plate with a slight bulge in the center; the ring was simply a line of light, but it stood out against the background of star-studded blackness and exaggerated the flattening of the giant world.

As power was applied both to kill the moon's...o...b..tal velocity and bring them out of Mesklin's equatorial plane the picture changed. The ring showed for what it was, but even the fact that it also had two divisions did not make the system resemble that of Saturn. Mesklin's flattening was far too great for it to resemble anything but itself-a polar diameter of less than twenty thousand miles compared to an equatorial one of some forty-eight thousand has to be seen to be appreciated. All the expedition members had seen it often enough now, but they still found it fascinating.

The fall from the satellite's...o...b..t gave the rocket a very high velocity, but, as Rosten had said, it was not high enough. Power had to be used in addition; and although the actual pa.s.s across the pole was made some thousands of miles above the surface, it was still necessary for the photographer to work rapidly. Three runs were actually made, each taking between two and three minutes for the photography and many more for the whipping journey around the planet. They made reasonably sure that the world was presenting a different face to the sun each time, so that the height of the cliff could be checked by shadow measurements on all sides; then, with the photographs already fixed and on one of the chart tables, the rocket spent more fuel swinging its hyperbola into a wide arc that intercepted Toorey, and killing speed so that too much acceleration would not be needed when they got there. They could afford the extra time consumed by such a maneuver; the mapping could proceed during the journey.

Results, as usual with things Mesklinite, were interesting if somewhat surprising. In this case, the surprising fact was the size of the fragment of planetary crust that seemed to have been thrust upward en bloc. It was shaped rather like Greenland, some thirty-five hundred miles in length, with the point aimed almost at the sea from which the Bree had come. The river leading to it, however, looped widely around and actually contacted its edge at almost the opposite end, in the middle of the broad end of the wedge. Its height at the edges was incredibly uniform; shadow measurements suggested that it might be a trifle higher at the point end than at the Bree's present position, but only slightly. There were no sawtooth shadows to indicate gaps in the wall.

Except at one point. One picture, and one only, showed a blurring of the shadow that might be a gentler slope. It was also in the broad end of the wedge, perhaps eight hundred miles from where the ship now was. Still better, it was upstream-and the river continued to hug the base of the cliff. It looped outward at the point where the shadow break existed as though detouring around the rubble pile of a collapsed slope, which was very promising indeed. It meant that Barlennan had sixteen or seventeen hundred miles to go instead of fifty, with half of it overland; but even the overland part should not be overwhelmingly difficult. Lackland said so, and was answered with the suggestion that he make a more careful a.n.a.lysis of the surface over which his small friend would have to travel. This, however, he put off until after the landing, since there were better facilities at the base.

Once there, microscopes and densitometers in the hands of professional cartographers were a little less encouraging, for the plateau itself seemed rather rough. There was no evidence of rivers or any other specific cause for the break in the wall that Lackland had detected; but the break itself was amply confirmed. The densitometer indicated that the center of the region was lower than the rim, so that it was actually a gigantic shallow bowl; but its depth could not be determined accurately, since there were no distinct shadows across the inner portion. The a.n.a.lysts were quite sure, however, that its deepest part was still well above the terrain beyond the cliffs.

Rosten looked over the final results of the work, and sniffed.

"I'm afraid that's the best we can do for him," he said at last. "Personally, I wouldn't have that country on a bet even if I could live in it. Charlie, you may have to figure out some way to give moral support; I don't see how anyone can give physical."

"I've been doing my best all along. It's a nuisance having this crop up when we were so close to home plate. I just hope he doesn't give us up as a bad job this close to the end; he still doesn't believe everything we say, you know. I wish someone could explain that high-horizon illusion to his-and my-satisfaction; that might shake him out of the notion that his world is a bowl, and our claim to come from another is at least fifty percent superst.i.tion on our part."

"You mean you don't understand why it looks higher?" one of the meteorologists exclaimed in a shocked tone.

"Not in detail, though I realize the air density has something to do with it."

"But it's simple enough-"

"Not for me."

"It's simple for anyone. You know how the layer of hot air just above a road on a sunny day bends sky light back upward at a slight angle, since the hot air is less dense and the light travels faster in it; you see the sky reflection and tend to interpret it as water. You get more extensive mirages sometimes even on Earth, but they're all based on the same thing-a *lens' or *prism' of colder or hotter air refracts the light. It's the same here, except the gravity is responsible; even hydrogen decreases rapidly in density as you go up from Mesklin's surface. The low temperature helps, of course."

"All right if you say so; I'm not a-" Lackland got no chance to finish his remark; Rosten cut in abruptly and grimly.

"Just how fast does this density drop off with alt.i.tude?" The meteorologist drew a slide rule from his pocket and manipulated it silently for a moment.

"Very roughly, a.s.suming a mean temperature of minus one-sixty, it would drop to about one percent of its surface density at around fifteen or sixteen hundred feet." A general stunned silence followed his words.

"And-how far would it have dropped at-say-three hundred feet?" Rosten finally managed to get the question out. The answer came after a moment of silent lip movement.

"Again very roughly, seventy or eighty percent-probably rather more."

Rosten drummed his fingers on the table for a minute or two, his eyes following their motions; then he looked around at the other faces. All were looking back at him silently.