by Hal Clement
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.
“I suppose no one can suggest a bright way out of this one; or does someone really hope that Barlennan’s people can live and work under an air pressure that compares to their normal one about as that at forty or fifty thousand feet does to ours?”
“Maybe he doesn’t use the air as we—” someone began.
“Of course he doesn’t; he reduces unsaturated hydrocarbons with free hydrogen. He still needs a certain minimum concentration of hydrogen to keep him supplied, and probably a minimum pressure to get it into his tissues. I’ll bet a large sum that it’s not far below the concentration and pressure he gets in his regular atmosphere. How about it, Charlie? You’re no biologist, but you know Barlennan.”
“I’m not sure.” Lackland frowned in concentration, and Rosten brightened a trifle. “There was some reference a long time ago to his staying under water—excuse me, under methane—for quite a while, and swimming considerable distances. You remember those river dwellers must have moved the Bree by doing just that. If it’s the equivalent of holding breath or a storage system such as our whales use, it won’t do us any good; but if he can actually get a fair part of the hydrogen he needs from what’s in solution in Mesklin’s rivers and seas, there might be some hope.” Rosten thought for a moment longer.
“All right. Get your little friend on the radio and find out all he knows himself about this ability of his. Rick, look up or find out somehow the solubility of hydrogen in methane at eight atmospheres pressure and temperatures between minus one forty-five and one eighty-five Centigrade. Dave, put that slide rule back in your pocket and get to a calculator; get as precise a value of the hydrogen density on that cliff top as physics, chemistry, math, and the gods of good weathermen will let you. Incidentally, didn’t you say there was a drop of as much as three atmospheres in the center of some of those tropical hurricanes? Charlie, find out from Barlennan whether and how much he and his men felt that. Let’s go.”
The conference broke up, its members scattering to their various tasks. Rosten remained in the screen room with Lackland, listening to his conversation with the Mesklinite far below.
Barlennan agreed that he could swum below the surface for long periods without trouble; but he had no idea how he did it. He did not breathe anyway, and did not experience any feeling comparable to the human sense of strangulation when he submerged. If he stayed too long and was too active, the effect was rather similar to sleepiness, as nearly as he could describe it; if he actually lost consciousness, however, it stopped there; he could be pulled out and revived as much later as anyone cared as long as he didn’t starve in the meantime. Evidently there was enough hydrogen in solution in Mesklin’s seas to keep him alive, but not for normal activity, Rosten brightened visibly.
“There is no discomfort of the sort you suggest in the middle of worst storms I have ever experienced,” the captain went on. “Certainly no one was too weak to hold on during that one which cast us on the island of the gliders—though we were in its center for only two or three minutes, of course. What is your trouble? I do not understand what all these questions are leading to.”
Lackland looked to his chief for permission, and received a silent nod of affirmation.
“We have found that the air on top of this cliff, where our rocket is standing, is very much thinner than at the bottom. We doubt seriously that it will be dense enough to keep you and your people going.”
“But that is only three hundred feet; why should it change that much in such a short distance?”
“It’s that gravity of yours; I’m afraid it would take too long to explain why, but on any world the air gets thinner as you go higher, and the more the gravity the faster that change. On your world the conditions are a trifle extreme.”
“But where is the air at what you would call normal for this world?”
“We assume at sea level; all our measures are usually made from that reference.” Barlennan was thoughtful for a little while. “That seems silly; I should think you’d want a level that stayed put to measure from. Our seas go up and down hundreds of feet each year—and I’ve never noticed any particular change in the air.”
“I don’t suppose you would, for several reasons; the principal one is that you would be at sea level as long as you were aboard the Bree, and therefore at the bottom of the atmosphere in any case. Perhaps it would help you to think of this as a question of what weight of air is above you and what weight below.”
“Then there is still a catch,” the captain replied. “Our cities do not follow the seas down; they are usually on the seacoast in spring and anywhere from two hundred miles to two thousand inland by fall. The slope of the land is very gentle, of course, but I am sure they are fully three hundred feet above sea level at that time.”
Lackland and Rosten stared silently at each other for a moment; then the latter spoke.
“But you’re a lot farther from the pole in your country . . . but no, that’s quibbling. Even if gravity were only a third as great you’d be experiencing tremendous pressure changes. Maybe we’ve been taking nova precautions for a red dwarf.” He paused for a moment, but the Mesklinite made no answer. “Would you be willing, then, Barlennan to make at least an attempt to get up to the plateau? We certainly will not insist on your going on if it proves too hard on your physical make-up, but you already know its importance to us.”
“Of course I will; we’ve come this far, and have no real reason to suppose what’s coming will be any worse than what’s past. Also, I want—” he paused briefly, and went on in another vein. “Have you yet found any way of getting up there, or is your question still hypothetical?” Lackland resumed the human end of the conversation.
“We have found what looks like a way, about eight hundred miles upstream from your present position. We can’t be sure you can climb it; it resembles a rock wall of very moderate slope, but we can’t tell from our distance how big the rocks may be. If you can’t get up there, though, I’m afraid you just can’t get up at all. The cliff seems to be vertical all around the plateau except for that one point.”
“Very well, we will head upstream. I don’t like the idea of climbing even small rocks here, but we’ll do our best. Perhaps you will be able to give suggestions when you can see the way through the vision sets.”
“It will take you a long time to get there, I’m afraid.”
“Not too long; for some reason there is a wind along the cliff in the direction we wish to go. It has not changed in direction or strength since we arrived several score days ago. It is not as strong as the usual sea wind, but it will certainly pull the Bree against the current—if the river does not grow too much swifter. They often do, of course, in their upper reaches.”
“This one does not grow too much narrower, at any rate, as far as you will be going. If it speeds up, it must be because it grows shallower. All we can say to that is that there was no sign of rapids on any of the pictures.”
“Very well, Charles. We will start when the hunting parties are all in.”
“Have they found anything on land yet?”
“A few small animals have been netted, and some of the vegetation had edible fruit or leaves. Our main source of food is the river, though.”
“Any people—villages, cities, or such like?”
“Not even lone wanderers. There were places in the plant groves where there should have been traces if anyone at all was around, but nothing of the sort was seen. The place could support people, but doesn’t seem to.”
“All right. I was just wondering for the sake of my ethnological friend. He’s rather disappointed, I think, that you still have three vision sets in your possession.”
“I’m rather surprised that we have after those glider makers. I was expecting that Reejaaren to confiscate the lot as a fine if one of you had spoken while h
e was aboard.”
“I’m sure you could have talked him down to one. I’m surprised you didn’t take one of their gliders with you when you left.”
“I wanted to, but there really wasn’t room on the ship.” The conversation ended on that note, and Barlennan prepared to resume his upstream journey.
One by one the parties came back to the ship, all with some food but none with anything interesting to report. The rolling country extended as far in all directions as anyone had gone; animals were small, streams scarce, and vegetation sparse except around the few springs. Morale was a trifle low, but it improved with the news that the Bree was about to travel again. The few articles of equipment that had been disembarked were quickly reloaded on the rafts, and the ship pushed out into the stream. For a moment she drifted seaward, while the sails were being set; then they filled with the strangely steady wind and she bore up against the current, forging slowly but steadily into unknown areas of the hugest planet man had yet attempted to explore.
XVI.
Barlennan rather expected the river banks to become more barren as his ship ascended the stream, but if anything, the reverse was the case. Clumps of sprawling, octopuslike growths hugged the ground at either bank, except where the cliff on his left crowded the river too closely to leave them room. After the first hundred miles from the point where they had waited several streams were seen emptying into the main course; and a number of the crewmen swore they saw animals slinking among the plants. The captain was tempted to land a hunting party and await its return, but two considerations decided him against it.
One was the wind, which still blew steadily the way he wanted to go; the other was his desire to reach the end of the journey and examine the miraculous machine the Flyers had set down and lost on the polar wastes of his world. What he could learn from that device would make him superior to the canoe-makers and glider-builders of the tropics, as well as the more conventional races of the middle latitudes.
As he had said, he could do just about as he pleased, and not a living creature on Mesklin would have the ability to deny him. To do him justice, he had no desire to embark on the career of a super-criminal; what he craved more was the adulation of the other members of his race. In spite of their weird outer forms and weirder body chemistry, the Mesklinites, as Lackland had said more than once, were amazingly human.
As the journey progressed, the captain grew more and more astonished at the wind; he had never before known it to blow steadily for more than a couple of hundred days in any direction. Now it was not merely maintaining direction but was turning to follow the curve of the cliff, so that it was always practically dead astern. He did not actually let the watch on deck relax completely, but he did not object when a man turned his attention away from his section of rigging for a day or so. He himself had lost count of the number of days since it had been necessary to trim sails.
Several conversations with the human meteorologists failed to cast light on the matter; they agreed, one and all, that any wind on Mesklin should be diverted so rapidly from its original course by the planet’s enormous rate of spin as to form a cyclonic cell almost at once. This was, in fact, the first place on the planet where this had failed to happen. Of course, the deflection in this case should be toward the cliff; but even so, atmospheric whirls that would at least vary the speed of the wind greatly should be forming. What bothered them still more was the energy source of the current; they knew the heat output of 61 Cygni and the reflecting power of Mesklin’s surface, and could account for most of the energy that struck the planet. There was not enough, at this point at least, to keep that wind going against ground friction. As the days went by they spent more and more time in the screen room, discussing the matter with each other and the Mesklinites who had learned English.
The river retained its width, as the Flyers had foretold; as they had also intimated was possible, it grew shallower and swifter. This should have slowed the Bree down, and actually did so; but not as much as it might have, for the wind began also to increase. Mile after mile went by, and day after day; and the meteorologists became frantic. Imperceptibly the sun crept higher in its circles about the sky, but much too slowly to convince those scientists that it was responsible for the increased wind force. It became evident to human beings and Mesklinites alike that something about the local physiography must be responsible; and at long last Barlennan became confident enough to slip briefly and land an exploring and hunting party, sure that the wind would still be there when he reembarked.
It was, and the miles flowed once more under the Bree’s rafts. Eight hundred miles, the Flyers had said. The current of the river made the log indication much more than that, but at last the break that had been foretold appeared in the wall of rock, far ahead of them.
For a time the river flowed straight away from it, and they could see it in profile—a nearly straight slope, angling up at about twenty degrees, projecting from the bottom fifty feet of the cliff. As they approached, the course of the stream bent out away from the wall at last, and they could see that the slope was actually a fanshaped spill radiating from a cleft less than fifty yards wide. The slope grew steeper within the cut, but might still be climbable; no one could tell until they were close enough to see what sort of debris composed the spill itself. The first near view was encouraging; where the river touched the foot of the slope, it could be seen to be composed of pebbles small even by the personal standards of the crew members. If they were not too loose, climbing should be easy.
Now they were swinging around to a point directly in front of the opening, and as they did so the wind at last began to change. It angled outward from the cliff, and its speed increased unbelievably. A roar that had sounded as a faint murmur for the last several days in the ears of crewmen and Earthmen alike now began to swell sharply, and as the Bree came directly opposite the opening in the rock the source of the sound became apparent.
A blast of wind struck the vessel, threatening to split the tough fabric of her sails and sending her angling across the stream away from the wall of rock. At the same instant the roar increased to almost explosive violence, and in the space of less than a minute the ship was struggling in a storm that vied with any she had encountered since leaving the equator.
It lasted only moments; the sails had already been set to catch a quartering wind, and they put enough upstream motion into the ship’s path to carry her across the worst of the wind before she could run aground. Once out of it, Barlennan hastily turned his vessel to starboard and ran her across the short remaining distance to shore while he collected his wits. This accomplished, he did what was becoming a habit in unfamiliar situations; he called the Earthmen, and asked for an explanation. They did not disappoint him; the voice of one of the weathermen answered promptly, vibrant with the overtones the captain had learned to associate with human pleasure.
“That accounts for it, Barl! It’s the bowl shape of that plateau! I should say that you’d find it easier to get along up there than we had believed. I can’t see why we didn’t think of it before!”
“Think of what?” The Mesklinite did not actually snarl, but his puzzlement showed clearly to the crew members who heard him.
“Think what a place like that could do in your gravity, climate, and atmosphere. Look: winter in the part of Mesklin you know—the southern hemisphere—coincides with the world’s passage of its closest point to the sun. That’s summer in the north, and the ice cap boils off—that’s why you have such terrific and continual storms at that season. We already knew that. The condensing moisture—methane—whatever you want to call it gives up its heat and warms the air in your hemisphere, even though you don’t see the sun for three or four months. The temperature probably goes up nearly to the boiling point of methane—around minus one forty-five at your surface pressure. Isn’t that so? Don’t you get a good deal warmer in winter?”
“Yes,” admitted Barlennan.
“Very well, then. The higher temperature means t
hat your air doesn’t get thin so rapidly with altitude—you might say the whole atmosphere expands. It expands, and pours over the edge into that bowl you’re beside, like water into a sinking soup plate. Then you pass the vernal equinox, the storms die out, and Mesklin starts moving away from the sun. You cool off—right?—and the atmosphere shrinks again; but the bowl has a lot caught inside, with its surface pressure now higher than at the corresponding level outside the bowl. A lot of it spills over, of course, and tends to flow away from the cliff at the bottom—but gets deflected to the left by the planet’s spin. That’s most of the wind that helped you along. The rest is this blast you just crossed, pouring out of the bowl at the only place it can, creating a partial vacuum on either side of the cleft, so that the wind tends to rush toward it from the sides. It’s simple!”
“Did you think of all that while I was crossing the wind belt?” asked Barlennan drily.
“Sure—came to me in a flash. That’s why I’m sure the air up there must be denser than we expected. See?”
“Frankly, no. However, if you are satisfied I’ll accept it for now. I’m gradually coming to trust the knowledge of you Flyers. However, theory or no theory, what does this mean to us practically? Climbing the slope in the teeth of that wind is not going to be any joke.”
“I’m afraid you’ll have to. It will probably die down eventually, but I imagine it will be some months before the bowl empties—perhaps a couple of Earthly years. I can’t even make an educated guess, at this point—I’d need measurements of the wind speed, the size of the opening, the volume of the basin, and a whole set of air-pressure values scattered all over the plateau itself. For all I know, it may not finish before next winter; almost certainly, now that I think of it, it will go on until midsummer, when you’re farthest from the sun. That’ll be the best part of two Earth-years from now.
“I think, if it’s at all possible for you, Barl, it would be worth attempting the climb without waiting.”
