Mission of Gravity

„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 fall 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 well 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.”

„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.”

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 iri all directions as anyone had gone; animals were small, streams scarce, and vegetation sparse except around the few springy. 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: VALLEY OF WIND

Barle

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.

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 Barle

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 fan-shaped 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 land 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, Barle

„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 icecap 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?”