Hal Clement - Close to Critical

“He is now. He’s going out of sight the way he came. He definitely doesn’t carry an axe; we’ve seen all sides of himnow. He’s getting hard to see; there’s less of him visible above the bushes, and he’s getting out of range of our lights. Now he’s gone.”

Raeker glanced at a clock, and did some rapid mental arithmetic. “It’s about four hours to rainfall. Easy, did you say whether he was carrying a lighted torch, or fire in any form?”

“He definitely wasn’t. He could have had matches, or flint and steel, or some such fire-making apparatus in his pouch, of course.”

“Swift’s people don’t know about them. Nick’s group makes fire by friction, with a bow-drill, but I’m sure the others haven’t learned the trick yet. They certainly hadn’t yesterday—that is, three or four ship’s days ago. Anyway, the point I’m trying to get at is that if the one you saw had no fire, he was presumably within about four hours march, or not too much more, of Swift’s main group; and they’d almost have to be either at their caves or near the line between those caves and the point where Nick and the robot took to the river last night. He may be even closer, of course; you’d better keep your eyes open, and let us know immediately if the main body shows up. That would give us a still closer estimate.”

“I understand. We’ll look out for them,” replied Easy. “While we’re watching, how about getting out those language tapes you have? The sooner we start listening to them, the more good they’ll probably do us.”

Raeker agreed to this, and the next few hours passed without any particular incident. Nightfall, and then ram-fall, arrived without any further sign of natives; and when the drops grew clear the children stopped expecting them. They ate, and slept, and spent most of their waking hours trying to absorb what little Raeker had gleaned of Swift’s language. Easy did very well at this, though she was not Ij quite the marvel her father had claimed.

A complication which no one had foreseen, though they certainly should have, manifested itself later in the evening. The bathyscaphe began to move again, as the river formed around it and increased in depth. The children were quite unable even to guess at the rate of motion, though they could see plants and other bits of landscape moving by hi the glare of their lights; the speed was far too irregular. Even if they could have reported anything more precise than “sometimes a fast walk, sometimes a creep, and sometimes not at all,” they were not even sure when the motion had started. They had had their attention drawn to it by an unusually hard bump, and when they had looked outside the few features visible were already unfamiliar. They might have been drifting a minute or half an hour.

Raeker took some comfort from the event, though Easy had been slightly disposed to tears at first.

“This gives us one more chance of getting our own people to you ahead of Swift’s,” he pointed out. “The cave men will have the job of hunting for you all over again, while we are getting you more closely located all the tune.”

“How is that?” asked Easy hi a rather unsteady voice. “You didn’t know where we were before we started moving, we don’t know which way we’re moving, how fast, or when we started. I’d say we know less than we did last night, except you can’t know less than nothing.”

“We don’t know,” granted Raeker, “but we can make a pretty intelligent guess. We judged that you were within a few hours’ walk—say twenty-five or thirty miles—of the line between Swift’s caves and our people’s camp. We are about as sure as we can be without having actually mapped the entire area that this region is in the watershed of the ocean Nick’s people found. Therefore, you are being carried toward that sea, and I’ll be greatly surprised if you don’t wind up floating on it, if not tonight at least in the next night or two. That means that Nick will only have to search along the coast on land if you don’t reach the ocean tonight, or look offshore for lights if you do. I shouldn’t think you’d go far out to sea; the river will lose its push very quickly after getting there, and there’s no wind to speak of on Tenebra.”

Easy had brightened visibly as he spoke. Amina-dorneldo, also visible on the screen, had not made any change of expression detectable to the human watchers, but the girl had cast a glance or two his way and seemed to be satisfied with the effect of Raeker’s words on him. Then a thought seemed to strike her, and she asked a rather pointed question.

“If we do get carried out on the sea, what do Nick’s people or anyone else do about it?” she asked. “We’ll be out of his reach, and out of Swift’s reach, and you say there aren’t any winds on this planet, though I don’t see why.”

“The pressure’s so high that the atmosphere doesn’t even come close to obeying the classical gas laws,” replied Raeker—he was no physicist, but had had to answer the question quite a few times in the last decade and a half— “and the small percentage changes in temperature that do occur result in even smaller changes in volume, and therefore in density, and therefore in pressure. Little pressure difference means little wind. Even changing phase, from gas to liquid, makes so little change in density that the big raindrops just drift down like bubbles, in spite of the gravity.”

“Thanks, I’ll remember to make sense of that when I get back to school,” said Easy. “You’re probably right, but you haven’t answered my question about how Nick was going to reach us if we went out to sea. Forgive me if I’m spoiling an attempt to change the subject.”

Raeker laughed aloud, for the first time in some weeks.

“Good kid. No, I wasn’t trying to change the subject; you just asked a question that every visitor for sixteen years has put to me, and I answer it without even thinking. You pushed a button. As far as your question goes, leave it to me. I’m going to talk to Nick first thing in the morning—he couldn’t do anything right now.”

“All right,” said Easy. “If you’re that sure, I won’t worry. Now how will we be able to tell when we reach the sea?”

“You’ll float, the way you did in the lake, at least when some of the water boils off in the morning. I shouldn’t be surprised if you were carried off the bottom even at night when the river reaches the sea, but I’m not certain of it. I don’t know how completely or how far down the water dilutes the acid. Keep an eye on the landscape, and if you start to drift up from it let us know,”

“All right. That’ll be easy.”

But they were still on the bottom when the ’scaphe stopped moving. The human beings at both ends of the communication line had slept in the meantime, but there were still some hours before local daylight was due. Something had slowed the current so that it was no longer able to push the big shell along, and Raeker suspected that the children had reached the ocean, but he admitted there was no way to be certain until day. The intervening time was used up with language work again; there was nothing else to do.

Then the ship began to rise gently off the bottom. The motion was so gradual that it was a minute or two before either of the youngsters was positive it was taking place, and more than three hours passed before the bottom could no longer be seen. Even then they had not reached the surface, or the surface had not reached them, depending on one’s viewpoint. It was definitely day by this time, however, and Raeker had lost practically all his doubt about the ship’s location. The river had dried up much more quickly, the day before. He told Easy what he was going to do, suggested that she listen in, and then called Nick.