by Hal Clement
“Not much change yet,” she reported. “Still no sign of any wall to this cave, and the stuff underneath is about the same. Not enough pressure or temperature change to read. Did you find any reasonable prelife compounds in the earlier samples, Jenny?”
“I haven’t had time to work on them yet. I haven’t been able to think of any other explanation for the atmosphere, either. That clay is going to get a real working over, as soon as we get you out of there.”
“Along with a few other things. Sorry to have delayed you.”
“Forgiven, considering what you’ll be bringing back with you.”
“It’s a pity, isn’t it?” remarked Charley.
“What?” asked all three women.
“That all this stuff has probably been worked out already, and we just haven’t been allowed to see the answers.”
“Are you sure it has?” asked Jenny.
“Enigma has been known for tens of thousands of years. It must have been used for a lab exercise for just about all that time. Do you really think there’s much chance that we’re doing or finding anything new? The School just seals the student reports—if they even keep them. It would be more fun if we were allowed to start where the earlier ones left off. Don’t you think so, Molly? Then we’d have reasonable hope of coming up with something actually new.”
“Personally,” remarked the Rimmore without waiting for Molly’s answer, “I’m happier not having my imagination limited by what someone has decided is the right answer. I know some discipline is needed for that particular tool, that’s why we were educated in the first place; but if I’m going to be confronted, back on Classroom, with a ’gramful of other people’s notions of why this place still has atmosphere, I want the one I come up with—or we come up with—to show up decently in the list.”
“Do you feel that way, too, Molly?” repeated the Kantrick.
“Yes, I think I do. Personally, I can believe that no one has been down in this cave before; I discovered it in such a silly fashion, and surely no one could have expected it.”
“Wind from the hole. For that matter, the wind from Carol’s trap, come to think of it.”
“Well, maybe, Joe. Anyway, I agree with Jenny about doing our own thinking, and it’s probably a good idea for a few more years for us to do it with lots of independent checkers. Anyway, I’m not worried about the philosophy just now. Work—data collecting and thinking—first; worry about getting hick to the rest of you alive, second—and maybe that will climb to first later; worry about what the Faculty thinks of my work, and what my friends think of it, not to mention what I think of it myself, third. First point, Joe—the wind is getting stronger, I think.”
“You can feel it?”
“I’m pretty sure. Just a minute while I get a handful of this stuff.” Molly reached down and collected some of the powdery crystals, tossing them upward. “Yes, they’re drifting backward quite a bit faster than before.”
“Is it strong enough to do anything to the undisturbed crystals?” asked Jenny.
“Just a minute. Not generally—but yes, around the base of the robot itself, where there are eddies, some of the stuff is being blown away. I’m starting to leave a blowing dust trail—a pretty, sparking one—behind me.”
“Suggestion. You could be approaching a wall of the cave, with the wind coming from a narrow, or relatively narrow, passage,” the chemist returned.
“Good thought. I’ll go back to narrow beam and look ahead as far as I can.” The others waited silently. Carol, now outside with the rope-laden robot, continued her work on its controls, but even her attention was divided. “Nothing in sight yet.” Three more times, at roughly one-minute intervals, Molly repeated this message. The situation was not really boring, of course; merely tense. A well-remembered chemistry exercise in the isolation lab on Beryl had been similar. There had been automatic dampers, of course, that might work in time to forestall an explosion; but the lab itself was on tall stilts, which combined with the little world’s lack of atmosphere to prevent the transmission of shock to surrounding structures if they didn’t. Molly had wondered at the time why she had not been allowed to perform the experiment by remote control; Rovor had been quite indignant about it. Now she thought she knew the reason. Here there was no equivalent to the dampers, but she found herself quite free of panic. The tendency for familiarity to breed calmness, if not actual contempt, was almost universal, not a Human peculiarity.
Carol by this time had satisfied herself about the key responses and was riding up the hill at some five times the pace her vehicle’s predecessor, or predecessors, had taken. She could have set in a still higher speed, but prudently used one within her own running capabilities. She was not planning to get off, but she had not planned to fall into a crater before, and Molly had not planned to go underground.
And Joe had certainly not planned to blow away, she was sure.
She watched everything around her carefully as she went; if the rope failed for any reason, her memory would serve one of its functions. The cord, which Molly would have thought of more as fishline than rope, had been fastened to a rod driven into the ground near the base of the hill, and way paying out comfortably from the top of the cylinder; Carol kept carefully clear of it. It was thin material, but far too strong for her to break if she became tangled in it. She had a knife, of course, but felt strongly that having to use it would be glaring evidence of carelessness.
“Still nothing in sight” came Molly’s voice.
Over the edge of the crater. It occurred to Carol that the air from below must be cooler than surface atmosphere; it would not have poured down the side of the cone to guide the robots otherwise. Down the slope, over the central hole. A straight letdown into the hole; she had not altered Joe’s original programming on this point. Almost at once a steep slope that the machine treated as a surface, flying into the wind—down the slope—at its set speed. Carol herself could feel the wind at first; then it decreased rapidly. She could still see fairly well without her hand light and was not surprised that the passage was growing larger.
“Still nothing in sight.”
Now it was a good deal steeper, and the little Shervah could picture her giant friend helplessly rolling down into the darkness ahead. Within seconds she had to use her own lamp, and before long the surface leveled and was covered with the same sort of sand as that composing the cone above. Carol was not surprised; she had guessed how the cone had been formed.
“Molly, I’m about at the place where you must have let the robot catch up with you. It’s past a steep slope of rock where you certainly couldn’t have stopped yourself, and I can see marks in the sand that you probably left.”
“Good. It’s awhile yet to the cave. Joe, I suppose you’re tracking Carol’s machine as carefully as possible.”
“I am indeed. I already suspect the cause of the earlier reading uncertainties. I should have thought of it earlier.”
“I’d welcome you to the club, if you weren’t the founder. What’s the answer?”
“Refraction index. The electromagnetic waves—radio waves—are not only absorbed by the rock but slowed by it, so both timing and direction measurements are affected. The rock of course is not uniform, and every time either the transmitter or the receiver moved, the beam was going through a different length of different medium. Hence kilometers of probable error.”
“Have any of you studied enough about Humanity to have gotten the term ’twenty-twenty hindsight’ into your translators?” asked Molly.
“I have,” said Charley. “Very appropriate.”
The Human did not have time to express her surprise; her attention was taken up by something more immediate.
“Cave wall ahead, I think!” she called suddenly. “The wind is a lot harder. I should have told you earlier the floor is bare rock; it looks as though the crystals couldn’t hold up in the draft.”
“Bare rock, or the sticky stuff?” asked Jenny promptly.
“Roc
k. I’m sorry; I should have made more checks under the crystals. We can do it on the way back, or if Carol has time she can pause coming over—but watch out, Carol; remember the crystals are a good deal deeper than your height, at least in some places, and the stuff at the bottom is quite adhesive. You’re not as strong as I am, and if you couldn’t pull loose the situation would become rather awkward.”
“I’ll control myself,” the Shervah assured her listeners. “Are you close enough to the cave wall to see where the wind is coming from?”
“Quite close—two or three hundred meters, I’d guess—but I can’t see any passages or openings in it yet. I should go right to whatever it is, so I’m looking straight ahead, but still just dark rock. That may be the trouble, of course; the passage won’t be much, if any, darker. I’m very close now—fifty meters—less; still nothing—uh-oh. Joe!” “Yes, Molly?”
“I should have paid more attention to the programs in these things. What will they do if they can’t go forward?” “How can that happen?”
“Meaning you didn’t consider it in the program. The wind is coming through a horizontal crack that seems to start thirty or forty meters to my left and is about thirty centimeters high at the point I’m approaching. It continues to get higher to my right, as far as my light will let me see. This machine won’t fit into a crack of this height. It’s going to run into the rock and stop, and either the controls are going to do something about the situation, or something is going to break. Which will it be, Joe?”
The Nethneen was silent for a number of seconds, and Molly resumed her report.
“About ten meters to go. Should I get off? Will anything burn out if it tries to push the planet out of the way? This machine has a fusion unit in it, after all.”
“No. It won’t push hard enough to damage its drive or its shell; that’s basic to the control system, and I had nothing to do with it,” the little being finally said. “Nothing should burn out, blow up, or break. I’ll have to think out whether being held motionless will be treated like an eddy—let’s see—it can’t count the number of times around, obviously…”
“Contact,” reported the Human. Silence followed.
“If you’re just staying there, I’ll be able to catch you that much quicker,” Carol had time to say.
“I’m not. It’s going to the right, just scraping against the wall. That’s the way the crack is getting wider. If that continues, the machine will fit in pretty soon and I’ll be scraped off the top. Why is it doing this, Joe?”
“At the moment, I have no idea. Please keep reporting.”
“What’s the rock like?” asked Carol. “Is the crack a fault, or an erosion product, or what?”
“I wouldn’t know even if I could see it better, I’m afraid. Obviously wind goes through it; if that ever carries sand, it would explain any amount of erosion. I haven’t seen any liquid yet. The top of the crack is nearly up to the top of the robot; the bottom has been a continuation of the cave floor all along, not that that makes it very level. I’m getting off and following on foot. If the thing does go in, I can too, though not very comfortably. The top rises rather suddenly to nearly my own height, about eight or ten meters ahead, and then levels off, and then the crack comes to an end as far as I can see. It would be nice if your mystery controller showed enough liking for a Human to go over to that point before going in, Joe.”
“I don’t see why it should—nothing personal, of course—but then I don’t see why it’s doing this anyway. If it goes to the high part—hmmm. Let’s see.”
“Don’t start calculating yet. That’s not even a hypothesis, dear colleague. Wait.”
“For how long?”
“Ten ... five, four, three, two, sorry—speed not as constant as I thought. Wall’s curved. We’re there, and it’s going in. I don’t like the idea, but I guess I’d better follow.”
“Wouldn’t it be wiser to wait for me?” asked Carol.
“If there were no doubt that you’d avoid all trouble on the way, and I suppose it is a pretty safe bet, yes. However, if you don’t get here—if you run out of rope because measures were off, or your robot doesn’t follow the same track as this one because the underground winds aren’t as steady as we’re hoping, or something none of us has thought of yet—then I’d better stay in reach of that machine. My armor has battery power for a few days—just how long depends on what it has to do in the way of temperature control—but any longer and I’ll have to recharge. The robot has a fuser, and I can plug into the slave feeder on the top. That machine could be air, food, and drink to me for months, much as I hate the thought of being in here anything like that long.”
“You’re not really serious about that, are you?” Charley’s tone was as protesting as his choice of words.
“Very serious about not wanting it. I consider the possibility too serious to ignore. I’m staying with the machine until Carol catches me, though I’m nearly certain that she will. I’m not going to report for a while, unless it’s something urgent. I’m still connected by rope, but this passage isn’t quite high enough for real walking, and even in this gravity I don’t want my armor to be dragged.”
“If you have a chance to turn your light to both sides, Molly, you might tell me something about the shape of the passage you’re in. I know where you entered it was higher than it had previously been; the portion passed, which I judge is now to your left, was at that time lower. Might I hazard a guess that you are now under a rather low roof and that it gets higher to your left, and that there is very little of the passage at all to your right?”
“Wait a minute. If you’re right, I could go to my left and stand up, which would be a relief—all right, you diminutive genius, how did you work that one out?”
“I claim no more than a guess—there probably was, and remains, a vast number of possibilities that have not yet occurred to me. However, there must have been a small wind component, or a pressure effect that the robot would interpret as one, to the right along the cave wall outside, or it would not have traveled in that direction. If the outward wind speed was higher where the crack was low and decreasing as you went along, Bernoulli effect would produce a slightly lower pressure on the left of the robot as you faced the wall. To have such a velocity change, there should be a relatively large chamber or passage beyond the crack. There were really too many possible variables. I repeat, it was a guess, and I should prefer not to make another such.”
Joe, the women knew, was genuinely embarrassed; Charley might have been less aware of his colleague’s feelings, but even he recognized that it was better to let the subject drop.
“Carol,” called the Kantrick, “have you reached that long drop yet?”
“Almost at its edge. I was just going to call you so Joe could check his timing. I’m over emptiness ... now!” “Any trouble with the rope?”
“None. We should have thought to provide some regular marking system along it, so that a really good measurement of distance could be obtained.”
“Welcome to the club!” came three voices.
“It would have added some time to that needed for making it, though,” added Jenny.
“I suspect even Molly, at the wrong end of the road, would admit that it would have been time well spent,” retorted the little planetologist. “Wouldn’t you, big friend?”
The Human’s answer was affirmative, but possibly not as immediate or enthusiastic as the Shervah would have liked. Joe was the one to alter the subject this time.
“I’m losing touch with your robot, too, Carol. I have been getting the same sort of depth measurements by triangulation that I did with Molly and feel quite sure that the uncertainties are due to the rock effects. If we really want to map your underground regions, we’ll have to make a new robot with a really good inertial system equipped to integrate its readings.”
“Fine! Let’s do it, as soon as Molly’s out of trouble!” exclaimed Jenny.
“Remember, friends—wind maps!” called Molly
softly. “We have plans, which are already somewhat out of shape, and we have only so much time before Classroom gets back.”
“If we get something really new, as you seem to hope, Molly, maybe we could stay here longer; they could fit Eighty-eight into the next run, I should think, without too much trouble, and pick us up then.”
“We’d better not plan on it, Charley,” replied the Human, “though I agree it’s a tempting idea. My impression is that Classroom is scheduled years ahead, and making a change would have an avalanche effect on other schedules. What we really need is a breakthrough—something that will convince the Faculty that this isn’t just a matter of adding trivial details to a picture whose outline is known. That might persuade them to arrange a special investigator of its own for Enigma. Unfortunately, we don’t know that we have one here. I’d like to believe that sort of thing could happen, but I’m not conceited enough to expect that I’ll be the one to do it.”
“Why not?” Charley asked in honest surprise. “Someone has to, and it does occur—sometimes every few years, always every few centuries. The Faculty knows that, don’t they? And the School is just the place for it to happen.”
“More likely in a physics lab than a planetology one, though,” Molly returned. She was about to ask Joe whether he didn’t agree with this point, when she remembered that it would not be tactful to suggest that he take sides in their debate. She was a little surprised to hear his voice anyway.
“We can’t afford to forget how the disciplines interlock,” he pointed out quietly. “Our studies here are no less physics than are those in a particle lab. If anything, we have more factors operating at once on any given observation; our problem would be to recognize the breakthrough when we encountered it, I fear.”
“Well, Charley’s right on one point, anyway. If I could write this up for home and bypass the School sealing, somehow—no, I can see why that wouldn’t be very popular. Bottom in sight yet, Carol?”
“Just. With my light, I think my eyes do better here than yours, though I’m certainly not sure. I’m definitely getting closer, and I can see light and dark as you did, though I’ll have to wait to be sure my light isn’t your dark, I suppose.”