„Yes,” admitted Barlennan.
„Very well, then. The higher temperature means that 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 the 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 dryly.
„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 think, if it’s at all possible for you, Barl, it would be worth attempting the climb without waiting.”
Barlennan thought. At the Rim, of course, such a hurricane would pick up a Mesklinite bodily and drive him out of sight in seconds; but at the Rim such a wind could never form, since the air caught in the bowl would have only a tiny fraction of its present weight. That much even Barlennan now had clear.
„We’ll go now,” he said abruptly to the radio, and turned to give orders to the crew.
The Bree was guided across the stream — Barlennan had landed her on the side away from the plateau. There she was dragged well out of the river and her tie lines secured to stakes — there were no plants capable of taking the desired load growing this close to the landslide. Five sailors were selected to remain with the ship; the rest harnessed themselves, secured the draglines of their packs to the harness, and started at once for the slope.
For some time they were not bothered by the wind; Barlennan had made the obvious approach, coming up the side of the fan of rubble. Its farthest parts, as they had already seen, were composed of relatively fine particles — sand and very small pebbles; as they climbed, the rock fragments grew | constantly larger. All could understand the reason for this; the wind could carry the smallest pieces farthest, and all began to worry a trifle about the size of the rocks they would have to climb over in the cut itself.
Only a few days were consumed in reaching the side of the wall’s opening. The wind was a little fresher here; a few yards on, it issued from behind the corner with a roar that made conversation ever harder as they approached. Occasional eddies struck them,’ giving a tiny taste of what was to come; but Barlennan halted for only a moment. Then, making sure that his pack was close behind him and securely attached to his harness, he gathered himself together and crawled into the full blast of the wind. The others followed without hesitation.
Their worst fears failed to materialize; climbing individual boulders was not necessary. Such huge fragments were present, indeed, but the downhill side of each was nearly covered by a ramp of finer material that had been swept into the relatively sheltered area by the everlasting wind. The ramps overlapped to a great extent, and where they did not it was always possible to travel across the wind from one to another. Their way was tortuous, but they slowly climbed.
They had to modify the original idea that the wind was not really dangerous. One sailor became hungry, paused in what he thought was shelter, and attempted to take a piece of food from his pack; an eddy around his sheltering rock, caused probably by his very presence which disturbed the equilibrium attained after months and years of steady wind, caught in the open container. It acted like a parachute, snatched its unfortunate owner out of his shelter and down the slope. He was gone from sight in a cloud of freshly disturbed sand in moments, and his fellows looked away. A six-inch fall under this gravity could kill; there would be many such falls before their comrade reached the bottom. If by chance there were not, his own hundreds of pounds of weight would be scraped against the rocks hard enough and fast enough to accomplish the same end. The survivors dug their feet in a little farther, and gave up all thought of eating before they reached the top.
Time after time the sun crossed ahead of them, shining down the cleft. Time after time it appeared behind, blazing into the opening from the opposite direction. Each time the rocks about them lighted up under its direct impact they were a little farther up the long hill; each time, they began at last to feel, the wind was just a little less furious as it roared past their long bodies. The cleft was visibly wider, and the slope gentler. Now they could see the cliff opening out forward and to each side; at last the way ahead of them became practically horizontal and they could see the broad regions of the upper plateau ahead. The wind was still strong, but no longer deadly; and as Barlennan led the way to the left it decreased still further. It was not sharply defined here as it was below; it fed into the cleft from all directions, but from that very fact its strength decreased rapidly as they left the cut behind them. At long last they felt safe in stopping, and all immediately opened their packs and enjoyed a meal for the first time in some three hundred days — a long fast even for Mesklinites.
With hunger attended to, Barlennan began to look over the country ahead. He had stopped his group to one side of the cut, almost at the edge of the plateau, and the ground sloped down away from him around nearly half the compass. It was discouraging ground. The rocks were larger, and would have to be traveled around — climbing any of them was unthinkable. Even keeping to one direction among them would be impossible; no one could see more than a few yards in any direction once the rocks surrounded him, and the sun was utterly useless as a means of guidance. It would be necessary to keep close to the edge (but not too close; Barlennan repressed an inward shudder). The problem of finding the rocket when they reached its neighborhood would have to be solved on the spot; the Flyers would surely be able to help there.
The next problem was food. There was enough in the packs for a long time — probably for the eight hundred miles back to the point above the Bree’s old halting place; but there would have to be some means of replenishing the supply, for it would never last the round trip or maintain them at the rocket for any length of time. For a moment Barlennan could not see his way through this problem; then a solution slowly grew on him. He thought it over from every angle and finally decided it was the best that could be managed. Once settled on details, he called Dondragmer.
The mate had brought up the rear on the arduous climb, taking without complaint the bits of sand loosened by the others which had been hurled cruelly against him by the wind. He seemed none the worse for the experience, however; he could have matched the great Hars for endurance, if not for strength. He listened now to the captain’s orders without any show of emotion, though they must have disappointed him deeply in at least one way. With his duties clear, he called together the members of his watch who were present, and added to them half the sailors of the captain’s watch. Packs were redistributed; all the food was given to the relatively small group remaining with Barlennan, and all the rope except for a single piece long enough to loop through the harnesses of Dondragmer’s entire company. They had learned from experience — experience they had no intention of repeating.