by Hal Clement
“Rek? Bill? Hugh? Jan? I’m outside. I see what I’d guess is the ship if it’s still rolling downhill, and two other lights. Am I right about the ship, and should I get back to it now or investigate the other lights?”
“Investigate, please.” The human code came clearly. “Ship is rolling. We fell out. We’re the lights.” Venzeer knew that the personal mud tanks were open on top; the report was not really surprising.
“All right. I’ll keep you in sight. Head downhill if you can travel. It might be best if I stay where I can see you and the ship both, if it doesn’t stop moving soon. Bill? Rek? Are you out of control, or can you stop and come back?”
“I’m not sure about control,” the Habra’s voice came back. “I think we’ve stopped rolling, and I’ll test.”
At the same moment the Erthuma code, Janice’s tone this time, sounded. “Not sure of down. Armor neutral. Can see ship so far. Flying toward it.” No effort had been made by the group to distinguish between the words for swimming and flying; even the Erthumoi had come to regard the difference as a quibble.
Venzeer could now see the Compromise clearly, two or three hundred meters away. The fine sediment had stopped rising; presumably the rolling had stopped—
Then he realized that the vessel was no longer on the bottom. It took him perhaps a second to guess the cause; the Erthuma report was plenty of clue. He called urgently. “Bill! Rek! You’re going up! You must have lost the ballast when the ship rolled over!”
“Tanks covered,” came Hugh’s code.
“I guess whoever designed the covers didn’t allow for copper’s density, or somebody skimped the work. The slugs probably broke through after a few rolls. Bill or Rek! Do you have control?”
“No,” came the native’s calm voice. “Most of the fan tubes seem to be clogged. I’m turning on all the heat I can give; maybe that will work. If it’s mud, though, we’ll have to go out with portable water jets and wash them clear.”
“How could there be mud here?” asked Rekchellet. “You said the fine stuff settles from the sunward side of the ring, over two thousand kilos from here.”
“A lot of it’s extremely fine, and the currents in a five-hundred-kilo deep ocean can distribute stuff pretty evenly,” replied Bill. “I’m hoping it’s just ice, though.”
“How could ice be so finely powdered underwater?”
“Never mind theory!” Venzeer snapped in his turn. “You’re going up, and will be out of sight soon. Should I come after you, or stay with the ground types?”
“Stay with us.” The code message was immediate enough to seem emphatic. Venzeer felt a brief surge of indignation at getting an order from a wingless person, but the “person” part of the designation did mean something now.
“Why? You have lights. We can come back for you, if the ship gets back at all. I may be needed to help clear out the fans.”
“Find ballast first. Never will if we don’t mark it now. Stay where ship started up. Keep your light on.” It was the woman’s code tone. Her husband’s followed.
“Bill, run all fans you can. No matter how they point. Warm up surroundings.”
“I understand,” replied the native. “You think it’s ice.” There was no interrogation in his tone.
“Reasonable hope,” replied Janice.
“Why?”
“Not at bottom. Probably shelf of middle ice. Hill pushed up into lower pressure, slowly changed to high ice. Micro crystals, loose, growing as you take them up. Not really sediment. Grew in place.”
“Could be,” agreed the Habra. “But I hope we don’t have crystals growing in the fan ducts.”
“Set jammed fans at lowest speed,” Hugh suggested. “Engines will heat. May help.”
“If they don’t burn out. I’ll have to watch that. But it’s worth trying.”
“Shielding good conductor. Ice should hold surroundings at local melting point.”
“Janice,” Venzeer cut in, “I’m about where the ship started up. My lights don’t show any of the ballast slugs.”
“Maybe powder settled on them. Could still be partly middle ice. Stay on the bottom. Don’t risk being moved by currents, unless you can see a fixed mark.”
“Right. Can you see my light?”
“Yes. Be there soon,” Hugh replied. “Ship left trail. May not need light.”
“But do keep it on,” added his wife.
“If there’s a track, the ballast should be somewhere along it,” pointed out Venzeer.
“We hope so, too.”
There was silence for a time, broken finally by Rekchellet. “Bill! It looks on my board as though a main fan has burned out.”
“I’m afraid you’re right. It was jammed, and must have been too big for the heat to get far enough fast enough, even packed with ice. The other main one is running, and I’ll be more careful with the steering ones. I’m trying to keep us bow down, so the one that’s running will keep us from rising too fast, but I’m afraid the ice is still gaining on us. Can you still hear us, Venzeer? Erthumoi?”
“Yes. You can’t be very far up. I can’t see your lights any more, though. Can you, Hugh or Janice?” The notion that Erthuma eyesight could ever be in any way superior to that of a Crotonite would never have reached Venzeer’s consciousness a few weeks earlier.
“No. Not for some time,” replied Janice. “We’ve been looking down, anyway. Hugh, white lumps about the right size.” The other three waited tensely.
“We have two slugs,” Hugh finally reported. “White dust on them. We’ve cleared them, we could carry them, but will wait till we find the others. Jan, leave your light here. We’ll tie together again.”
“All right.”
“If all between us and you, Venz, should make a big pile. We can probably find them. You still want to help with ship?”
“How would I find it? I’m committed to the ballast team now, it seems to me.”
“True. My mistake. Come toward our lights searching.”
“All right.” This time his resentment of the order was only fleeting. After all, code was awkward, and requests took more words, and it was the most reasonable thing to do anyway. Venzeer quickly began to find slabs of copper.
Some indefinite distance above, the Habra spoke to his remaining companion. “Rek, you take over. Keep bow down—you can tell which way is down even with the globe iced up, can’t you?”
“Easily. I have air in here. Down is where I settle.”
“All right. I’m taking a water jet outside. I’ll use a safety line, of course, but be sure the lights stay on.”
“Right. Keep talking, so I know nothing’s happened to you. I have full heat in the tubes, too.”
“I know. The hull isn’t icing. It’s too bad we can’t heat your pressure sphere.”
“I’m warm enough.”
“I mean on the outside, so you could see.”
“Oh. That doesn’t matter now as long as I can tell which way is down.”
“Surely you want to draw.”
“Just describe things to me, and I’ll do my best.”
The descriptions were heard with interest, though faintly, by Venzeer, though not by his companions far below; sound travels well in water, and Crotonites can use their wing membranes for additional sound reception.
The news, however, was not encouraging. Compromise was still rising, however slowly. Each kilometer of elevation dropped the pressure some eighteen atmospheres and raised the melting point of high ice almost a fifth of a kelvin. Ice crystals formed preferentially on other ice crystals, and the heat crystallization released was carried away too quickly to impede the resulting growth usefully. High ice is less dense than liquid water, so Compromise was becoming more buoyant minute by minute. If she reached a level where the tube heaters could not keep her main frame clear, a large snowball would hit the underside of the ice shelf some time in the next day or two.
Of course, it might hit a solute-rich region and start melting again. Unfortunatel
y, the Habras had no charts of the currents this close to Darkside, and there was no way to guess the chances of this. Neither Bill nor Rekchellet thought for an instant of counting on it; they had the explorer’s willingness to take a chance, but were neither compulsive gamblers nor pathological optimists.
Rekchellet had had plenty of practice with the controls, if not quite as much as Bill, and he did everything he could think of to get useful work out of such jets as were clear. Now and then the native was able to get another steering unit into action, but there was nothing he could do about the lost main unit. He had known this at first glance; not only was its engine burned out, but also when he had cut the power the unit had cooled down below local freezing temperature rather quickly. Water had frozen inside, and high ice expands when it freezes . . .
If only they had even a few of the ballast slugs. They hadn’t; William had checked inside the tanks with the smashed tops, though almost sure it was a waste of time.
He had gotten three steering units back into operation and was working on a fourth when his light showed what he had feared and expected. One of the thinner tubes of the ship’s structure was turning white. For a moment he didn’t dare look at others of the same size; maybe it was only a local blockage of heat-exchange fluid. But hope, especially a forlorn hope, wasn’t enough. He had to know. He swept his light around. It wasn’t.
“Rek, I’m afraid we’re out of luck. The ship itself is starting to ice.”
“And I can’t get any more out the big fan we have. The other is hopeless, you say.”
“Right.”
“What will happen if I feed it power anyway? There’ll be heat, at least, I’d say.”
“At least. I’d prefer not to risk shorting a fuser.”
“What do we have to lose?”
“The ability to think of anything else, mainly.”
“Will your thoughts be heavy enough? We need weight or power. These pressure spheres—I suppose they changed things enough so your experience isn’t—by Planner!”
“What? Rek, have you—”
“I’ve been as stupid as if I’d never had wings. Think, ground it! The air lock sphere is evacuated, the way I left it when I last came inside. Stay clear while I let water in! Eight meters inside diameter—over a hundred tonnes—there. Which way are we going now? I must be twins. How could I be so stupid all by myself?”
“It was regular procedure. Our standard trim assumed both spheres empty.”
“I was still stupid. We’re not in a standard situation. Have we stopped rising?”
“Yes. Definitely. We’re going back down, slowly, but we’re going. All we have to do is find the others.”
“That shouldn’t be hard. You can hear us, can’t you, Venz?”
“Yes, barely,” came the answer. “Can you tell which direction our voices are coming from?”
“Not very well. Generally up. Water carries sound too fast; we get direction by knowing which wing the sound waves hit first. I don’t see how I can guide you; I don’t know which way the ship is pointing when you talk. You’ll have to find me.”
“But I can’t get any direction either, from inside the sphere.”
“Then when you reach the bottom—pardon me, Janice, the shelf—you’ll have to come outside and listen. Then you can give steering directions to Bill—for that matter, you can just have him follow you.”
“But how do I get outside? I’d have to evacuate the lock sphere again, and we’d start going up.”
“You’ll just have to be quick.”
“I suppose so.”
“Then our troubles are over,” Venzeer gloated. “As long as you don’t go deaf before you get to the bottom.”
“My wings are as good as yours,” retorted the illustrator. “Have you found all the ballast down there?”
“We haven’t counted very carefully,” Hugh responded, not worrying how the code added to the suspense of his hearers. “There were five thousand hundred-kilo ingots of copper in the tanks, as I recall. Venz found a real hill of the things before we got back together. The few Jan and I had turned up were just strays; I don’t think they mean much, but we’ve toted them back to the main pile. Just keep driving down. You can’t have gone very far sideways.”
This proved an optimistic guess. The sub had gone out of range of even the Compromise’s lights; she struck sharply on the solid surface of the shelf without having been spotted by the watchers below. It seemed to be dark, hard, semitransparent ice, level as far as Bill could tell, very different from the hillside the Compromise had originally struck. There was much vegetation, some of which was disintegrating, bubbling furiously, where crushed by the sub’s arrival. Presumably azide and enzymes, released and allowed to meet by the rupture of cell walls and organelles, were reacting to give free nitrogen—one of the known contributing causes of storms elsewhere in the ocean. The bubbles vanished almost instantly as the gas cooled and went into solution in two thousand atmospheres of pressure.
Rekchellet could not see any of this, since his sphere was still frosted, and Bill didn’t notice; it was nothing unusual to him. Venzeer heard the rushing, boiling sound briefly, and then the ship’s thrusters when he listened more carefully.
“Are you down?” he called.
“Yes,” replied Rekchellet. “You can’t see our lights, I assume. I’ll get outside. Bill, I’ll have to evacuate the lock, so you probably can’t keep us on the bottom for the next minute or two.”
“No matter.”
Even the Erthumoi could hear the sea rushing into the lock sphere, but in their armor could make no guess at the sound’s direction. Venzeer was pretty sure of it, and indicated to the others which way they should look.
“I’m outside,” the recorder called finally. “Make some kind of noise.”
Venzeer began talking. Hugh picked up one of the copper slugs and let it fall on another. Rekchellet was able to hear both sounds, but reported that the second was much clearer.
“Can you tell the direction?” asked his practical companion. There was a pause; Hugh, without instructions, continued his metal-on-metal broadcast.
“This way, I think, Bill.” Rekchellet swam slowly away from the sub.
“What do you mean, you think?” cried Venzeer.
“I can’t get rid of the feeling you may be behind me instead of in front. I keep feeling sure first you’re one way, then the other.”
“Can you feel or see any currents?” asked Janice.
“Sure. The plants show those. If I stop swimming, I’m carried past them. They lean, too.”
“Do we seem to be up or downstream from you.”
“Up.”
“That makes sense. You would have been carried down while you were out of sight.”
Rekchellet was impressed by this point; Bill was not. “You can’t expect currents to hold direction for any time,” the native pointed out. Janice had already made her point about the chaotic nature of Habranha’s weather and was not ready to dispute the voice of experience, but her husband offered what seemed to be the only sensible advice.
“Keep on the way you are, and let us know if the currents change. I’ll keep tapping.”
For fully half an hour the journey continued. To Bill’s admitted surprise, the current remained steady. Travel was slow, much slower than Rekchellet could have flown, because Bill had a great deal of difficulty steering the sub; most of its main drive had to be used to keep it near the bottom even with the lock full of water; and since the thruster itself was fixed in the hull, the Compromise had to travel almost nose down. Once, Rekchellet reported that the guiding sound was getting weaker, but after some discussion it was decided that this represented Hugh getting tired and dropping the ingot from a lower height. He and his wife standardized the dropping distance and took turns at the muscle work, and Rekchellet and the submarine continued their original direction.
Venzeer and his companions strained their eyes in the direction the Crotonite had first claimed
to hear the sub’s thruster, until Hugh noticed that this was also the direction from which the current was coming, and after some hesitation mentioned the fact. Thereafter they divided their attention both ways until a faint glow became visible—downcurrent. No one discussed the directional ambiguity of sound, even though one Crotonite had been right. Tact was still the order of the day.
“Told you my wings were good enough,” was the only remark made. This was by the recorder as Bill brought the submarine to a halt as close to the pile of ingots as he could. Venzeer said nothing.
But Rekchellet’s wings were not good enough for something else. Neither were Venzeer’s or Bill’s. None of them could lift one of the ingots alone, and the various rope slings which were improvised to let the Crotonites work together proved very awkward. A hundred-kilogram mass of copper, underwater in Habranhan gravity, weighs just over fifteen kilograms. A few hundred pieces of copper were moved by the flyers, but the rest were carried from pile to tanks by the wingless members of the team. A fifteen-kilogram weight means something to a pair of Erthuma legs when swim fins are involved, but with the structure of a Habranhan submarine there is no need to swim. One can climb very easily.
It was several days’ work, and man and wife were rather exhausted at the end of the job. They didn’t argue very hard when Bill pointed out regretfully that there was no way of getting to the Solid Ocean on one main thruster. They’d just have to try again.
They also refrained from making any remarks about relative flying skills. Janice still liked the Crotonites, and even her husband admitted that the flyers had put up well with the display of their personal inadequacy, though they couldn’t have been very happy about it. Or, as Hugh remarked in an afterthought, really appreciative of what the Erthumoi had done for them.
“Why should they be?” asked his wife. “The ground crawlers were saving their own lives, too.”
III. Between
Hugh still considered them ungrateful, and so he even tried to convince his wife, until they were back in atmosphere and could talk normally again. A day after getting rid of the diving fluid, revived by appropriate relaxation, they met with Bill and the Crotonites for a planning session on the next trip. Hugh fully expected the latter to say they didn’t want Erthumoi along. He knew such a reaction would be illogical, but he still regarded Crotonites as illogical beings; after all, they had a low opinion of people who couldn’t fly, didn’t they?
