"A couple of hours. You can stand it all right."

Rich cut in at this point.

"Suppose the machine pa.s.ses over your robot's location before getting rid of its speed, Mr. Sakiiro? What will the autopilot do? Try to dive in at that point?"

"Certainly not. This is a vehicle, not a missile. It will circle the point at a distance which doesn't demand more than an extra half-G to hold it in the turn. If necessary, it will try to land the ship; but we should be able to avoid that."

"How? You don't expect Easy to fly it, do you?"

"Not in the usual sense. However, when she's down to what we can call 'flying' speed, the main buoyancy tanks of the 'scaphe should be full of the local atmosphere. Then I'll tell her how to start the electrolyzers; that will fill them with hydrogen, and the ship should float, when they're full, at an alt.i.tude where boosters can be used.

Then she and her young friend can trim the ship so that 66 CLOSE TO CRITICAL.

she's hanging nose up, and fire the rest of the boosters. We can be waiting overhead."

"I thought you said the boosters weren't connected to the control panel yet!"

Sakiiro was silent for a moment.

"You're right; I'd forgotten that. That complicates the problem."

"You mean my kid is marooned down there?"

"Not necessarily. It's going to call for some tight maneuvering; but I should think we could rig boosters on this boat so as to be able to reach the 'scaphe when it's floating at its highest. The whole design object, remember, was for the thing to float high enough for hydroferron boosters to work; and if they'll work on one frame, they'll certainly work on another."

"Then you can rescue her." The statement was more than half a question. Sakiiro was an honest man, but he had difficulty in making an answer. He did, however, after a moment's hesitation, staring into the face of the middle-aged man whose agonized expression showed so clearly on his screen.

"We should be able to save them both. I will not conceal from you that it will be difficut and dangerous; transferring an engineer to the outside of the 'scaphe to finish up wiring, while the whole thing is floating like a balloon, from a rocket hanging on booster blasts, will present difficulties."

"Why can't you transfer the kids to the rescue ship?"

"Because I'm pretty sure their s.p.a.ce suits won't stand the pressure at the 'scaphe's floating height," replied Sakiiro. "I don't know about Drommian designs, but I do know our own."

"Mr. Sakiiro." Easy's voice cut back into the conversation.

"Yes, Easy."

"Is there anything more I can do? Just sitting here doesn't seem right, and-it scares me a little."

Communication; Penetration; Isolation 67 Rich looked appealingly at the engineer. As a diplomat, he was an accomplished psychologist, and he knew his daughter. She was not hysterical by nature, but few twelve-year-olds had ever been put under this sort of stress.

He himself was not qualified to suggest any reasonable occupation to hold her attention; but fortunately Sakiiro saw the need, too.

"There are pressure gauges to your left," he said. "If you can give us a running report on their readings, while your friend tells us when he can first detect signs of dimming in the stars, it will be of some help. Keep it up unless you get too heavy to be able to watch easily; that may not be too long."

Rich looked his thanks; if Aminadabarlee was doing the same, no one was able to detect the fact. For long minutes the silence was broken only by the voices of the children, reading off numbers and describing the stars.

Then Easy reported that the ship was banking again.

"All right," said Sakiiro. "That means you're about over the robot. From now until your speed is killed, you're going to have to take better than three and a half gravities. Your seat folds back on its springs automatically to put you in the best position to stand it, but you're not going to be comfortable. Your friend can undoubtedly take it all right, but warn him against moving around. The ship's traveling fast in an atmosphere, and going from one air current to another at a few thousand miles can give quite a jolt."

"All right."

"The stars are getting hazy." It was Aminadorneldo.

"Thanks. Can you give me another pressure reading?"

The girl obliged, with detectable strain in her voice. Until the last turn had started, the 'scaphe was in relatively free fall; but with its rudimentary wings biting what little there was of the atmosphere in an effort to keep it in a turn the situation was distinctly different.

CXUSE TO CRITICAL.

Why the vehicle didn't go into a frame-shattering series of stalls, none of the engineers could see; the turn had started at a much higher speed than had been antic.i.p.ated by the designers of the machine. As it happened, the whole process was almost incredibly smooth-for a while.

Sakiiro, with no really objective data to go on, had about concluded that the vessel was down to gliding speed and was going to describe the location of the electrolysis controls to Easy when the motion changed.

A series of shuddering jars shook the ship. The girl's body was held in the seat by the straps, but her head and limbs flapped like those of a scarecrow in a high wind; the young Drommian for the first time failed to stay put. The jolting continued, the thuds punctuated by the girl's sobs and an almost inaudibly high- pitched whine from Aminador-neldo. The elder Drommian rose once more to his feet and looked anxiously at the screen.

The engineers were baffled; the diplomats were too terrified for their children to have had constructive ideas even had they been qualified otherwise; but Raeker thought he knew the answer.

"They're hitting raindrops!" he yelled.

He must have been right, it was decided afterward; but the information did not really help. The bathyscaphe jerked and bucked. The autopilot did its best to hold a smooth flight path, but aerodynamic controls were miserably inadequate for the task. At least twice the vessel somersaulted completely, as nearly as Raeker could tell from the way the Drommian was catapulted around the room. Sheer luck kept him out of contact with the control switches. For a time the controls were useless because their efforts were overriden-a rudder trying to force a left turn will not get far if the right wing encounters a fifty-foot sphere of water, even though the water isn't much denser than the air. Then they were useless because they lacked enough grip on the atmosphere; the ship had given up enough kinetic energy to Communication; Penetration; Isolation 69 the raindrops to fall well below its stalling speed-low as that was, in an atmosphere seven or eight hundred times as dense as Earth's at sea level. By that time, of coa.r.s.e, the ship was falling, in the oldest and simplest sense of the word. The motion was still irregular, for it was still hitting the drops; but the violence was gone, for it wasn't hitting them very hard.

The rate of fall was surprisingly small, for a three-G field. The reason was simple enough-even with the out- side atmosphere filling most of its volume, the ship had a very low density. It was a two-hundred-foot-long, cigar-like sh.e.l.l, and the only really heavy part was the forty-foot sphere in the center which held the habitable portion. It is quite possible that it would have escaped serious mechanical damage even had it landed on solid ground; and as it happened, the fall ended on liquid.

Real liquid; not the borderline stuff that made up most of Tenebra's atmosphere.

It landed upside down, but the wings had been shed like the speed brakes and its center of gravity was low enough to bring it to a more comfortable att.i.tude. The floor finally stopped rocking, or at least the Drommian did-with the vision set fastened to the ship, the floor had always seemed motionless to the distant watchers.

They saw the otterlike giant get cautiously to his feet, then walk slowly over to the girl's chair and touch her lightly on the shoulder. She stirred and tried to sit up.

"Are you all right?" Both parents fairly shrieked the question. Aminadorneldo, his father's orders in mind, waited for Easy to answer.

"I guess so," she said after a moment. "I'm sorry I bawled, Dad; I was scared. I didn't mean to scare 'Mina, though."

"It's all right, kid. I'm sure no one can blame you, and I don't suppose your reaction had much to do with your friend's. The main thing is that you're in one piece, /V CLOSE TO CRITICAL.

and the hull's intact-I suppose you'd be dead by now if it weren't."

"That's true enough," seconded Sakiiro.

"You've had a rough ride, then, but it should be over now. Since you're there, you might take a look through the windows-you're the first non-natives ever to do that directly. When you've seen all you can or want to, tell Mr. Sakiiro and he'll tell you how to get upstairs again. All right?"

"All right, Dad." Easy brushed a forearm across her tear-stained face, unfastened the seat straps, and finally struggled to her feet.

"Golly, when are they going to cut the power? I don't like all these G's," she remarked.

"You're stuck with them until we get you away from there," her father replied.

"I know it. I was just kidding. Hmm. It seems to be night outside; I can't see a thing."

"It is, if you're anywhere near the robot," Raeker replied, "but it wouldn't make any difference to your eyes if it were high noon. Even Altair can't push enough light for human eyes through that atmosphere. You'll have to use the lights."

"All right." The girl looked at the board where she had already located the light switches; then, to the sur- prised approval of the engineers, she made sure from Sakiiro that these were the ones she wanted. Saki ad- mitted later that his hopes of rescuing the pah* soared several hundred per cent at that moment.

With the lights on, both children went over to the windows.

"There isn't much to see," called Easy. "We seem to have splashed into a lake or ocean. It's as smooth as gla.s.s; not a ripple. I'd think it was solid if the ship weren't partly under it. There are big foggy globes drifting down, yards and yards across, but they sort of fade out Communication; Penetration; Isolation 71 just before they touch, the surface. That's every bit I can see." "It's raining," Raeker said simply. "The lake is probably sulphuric acid, I suppose fairly dilute by this time of night, and is enough warmer than the air so the water evaporates before it strikes. There wouldn't be any waves; there's no wind. Three knots is a wild hurricane on Tenebra."

"With all that heat energy running around?" Rich was startled.

"Yes. There's nothing for it to work on-I use the word in its physical sense. There isn't enough change in volume when the atmosphere changes temperature, or even changes state, to create the pressure differences you need for high winds. Tenebra is about the calmest place you'll find inside any atmosphere in the galaxy."

"Does that jibe with your remarks about earthquakes a while ago?" It was a measure of Aminadabarlee's re- vived confidence that he could talk of something besides the stupidity of human beings.

"No, it doesn't," admitted Raeker, "and I'll have to admit, Easy, that there is a possibility that you will encounter some waves if you float there long enough. However, you won't be able to call them weather, and they won't carry you to any more interesting places. I'm afraid you've seen about all you can expect to, young lady; you may as well come up and be properly rescued." "All right. Only I'd like to know just what's going to make this thing float, and whether the trip up will be as rough as the one down was."

"It won't. You'll go up vertically, and much more slowly. You're going to ride a balloon. The atmosphere there is mostly water, with enough ions loose to make it a decent conductor. The largest part of your hull is divided into cells, and each cell further divided in two by a flexible membrane. Right now, those membranes are squeezed flat against one wall of each cell by atmospheric 72.CLOSE TO CRITICAL.

pressure. When you start the electrolysis units, some of the water will be decomposed; the oxygen will be piped outside the hull, but the hydrogen will be released on the other side of the membranes and gradually drive the air out of the cells. The old bathyscaphe used the same idea, only it didn't need the membranes to keep the two fluids from diffusing into each other."

"I see. How long will it take to make enougft gas to lift us?"

"I can't tell; we don't know the conductivity of the atmosphere. Once you start things going, there's a bank of ammeters above the switches for each individual cell; if you'll give me their reading after things start, I'll try to calculate it for you."

"All right. Where are the- Oh, here; you labeled them decently. Upper right, a bank of twelve toggles, with a gang bar and a master?"

"That's it. You can see the meters above them. Close the lot, hit the master, and give the readings."

"All right." The thin arm reached up and out of the field of vision, and everyone could hear the switches click.

Easy pulled her hand back to her lap, settled back into the chair under her three hundred pounds of weight, eyed the dials one after another, and said, "The readings are all zero. What do I do now?"

V. PEREGRINATION; CONSIDERATION; ESTIVATION.

NICK had chosen a fire on the landward side of the hill, so he was the first to have to consider the sea-level problem. In the home valley, of course, the water at night had never gotten more than thirty or forty feet deep; slow as the runoff was, enough always escaped at the valley foot to keep the village itself dry. He knew, from f.a.gin's lectures, that the water which flowed away must eventually reach something like a sea or lake; but not even f.a.gin had stopped to think of what would happen then-naturally enough; the surface of Earth's oceans compared to the volume of an average day's rainfall doesn't correspond to much of a sea-level rise, to put it mildly.

On Tenebra, the situation is a trifle different. There is no single giant sea basin, only the very moderate-sized lake beds, which are even less permanent than those of Earth. What this difference could mean in terms of "sea" level might possibly have been calculated hi advance, but not by any of Nick's people.

At first, there was nothing to worry about. The great, cloudy drops drifted into sight from far above, settled downward, and faded out as the radiation from the fires warmed them a trifle. Then they came lower, and lower, until they were actually below the level of the hilltop on all sides.

73.74 CLOSE TO CRITICAL.

Once a sharp quake struck and lasted for half a minute or more, but when Nick saw that the spit of land joining the hill to the sh.o.r.e was still there, he put this from his mind. Something much more unusual was starting to happen. At home, raindrops which touched the ground after the latter had been cooled down for the night flattened into great, foggy half-globes and drifted around until a fire obliterated them; here they behaved differently. Drops striking the surface of the sea vanished instantly and by Nick's standards, violently. The difference in pressure and temperature made the reaction between oleum and water much less noticeable than it would be in an Earthly laboratory, but it was still quite appreciable.

After each such encounter, it could be seen that further raindrops falling on the same area faded out a little higher than usual for a few minutes; Nick judged correctly that some heat was being released by the reaction.

He had been watching this phenomenon for some time, interrupted twice by the need to relight his fire when a particularly close drop smothered it, when he noticed that the hill was not an island. This startled him a trifle, and he turned all his attention to the matter. The quake hadn't done it; he particularly recalled seeing the tombolo intact after the shaking was done. It didn't take him too long to conclude that if the land wasn't sinking, the sea must be rising; and a few minutes' close watch of the sh.o.r.e line proved that something of that sort was happening. He called the others, to tell them of what he had seen, and after a few minutes they agreed that the same thing was happening on all sides of the hill.

"How far will it come, Nick?" Betsey's voice was understandably anxious.

"I don't see how it can get this high," Nick1 answered. "After all, it hasn't risen as much as the water in our own valley would have by this time of night, and this hill is nearly as high as the village. We're safe enough."

It got a little harder to stick to this belief as the hours Peregrination; Consideration; Estivation 75 pa.s.sed and the sea grew higher. They could see the pools on sh.o.r.e swell and overflow into the main body; as time went on, more than one great river formed, carrying runoff from no one knew what drainage area.

Some of the rivers were frightening, their centers as high or higher than the hill itself before they spread out and merged with the sea. By this time the violence of water-meeting-acid had subsided; the sea, at least near the sh.o.r.e, was pretty dilute.

Of course, "near the sh.o.r.e" might be too casual a statement. No one on the hilltop could tell for certain just where the sh.o.r.e was now. The route they had followed was deep under the acid sea, and the only evidence that dry land existed was the rivers which still came into view above sea level.

The island that had been a hill shrank steadily. The cattle seemed unperturbed, but were driven inside the ring of fires. Then this had to be drawn in-or rather, others had to be built closer to the hilltop; and at last people and animals huddled together behind a single ring of glowing heat, while the sea bulged upward at their feeble protection. The raindrops were clear now; they had fallen from high enough levels to lose their suspended oxygen, and inevitably the last fires succ.u.mbed. Their heat had for many minutes past been maintaining a hollow in the surface of the sea; and as they cooled, the ocean reclaimed its own. Seconds after the last spark died every living being on the hilltop was unconscious, and a minute later only a turbulent dimple in the surface of the sea showed where the slightly warmer hilltop was covered. Nick's last thought was to the effect that at least they were safe from animals; they would be uncovered long before anything could get at them.

Apparently he wasn't quite right. When they woke up the next morning and brushed the thin frost of quartz crystals from their scales, all the people were there, but the herd seemed to have diminished. A count confirmed 76.CLOSE TO CRITICAL.

this; ten cattle were gone, with only a few scales left behind. It was fortunate that the animals were of a species whose scale armor was quite frail, and which depended more on its breeding powers to survive; otherwise the meat-eaters who had come in the night might have made a different choice. The realization that things lived in the sea came as a distinct shock to the entire party. They knew just about enough physical science to wonder where any such creature got its oxygen.

But the new situation called for new plans, "There seems to be a catch in the idea of telling f.a.gin just to hunt along the seash.o.r.e until he finds us,"

Nick commented after breakfast. "The seash.o.r.e doesn't stay put too well. Also, we can't afford to stay near it, if we're going to lose eight or ten per cent of our animals every night."

"What we'll have to do is some more mapping," commented Jim. "It would be nice to find a place protected by sea but which doesn't get submerged every night."

"You know," remarked Nancy in a thoughtful tone, "one could find a rather useful employment for this place right here, if the proper people could be persuaded to visit it." Everyone pondered this thought for a time, and the tone of the meeting gradually brightened. This did sound promising. Idea after idea was proposed, discussed, rejected, or modified; and two hours later a definite- really definite-course of action had been planned.

None of it could be carried out, of course, until it was possible to get off the island, and this was not for a dozen hours after sunrise. Once the tombolo appeared, however, everyone went into furious activity.

The herd-what was left of it-was driven ash.o.r.e and on inland by Betsey and Oliver. Nick, making sure he had his axe and fire-making equipment, started inland as well, but in a more southerly direction. The other five fanned out from the base of the peninsula and began mapping the countryside for all they were worth. They Peregrination; Consideration; Estivation 77 were to determine as closely as possible how much of the area was submerged by the sea at its highest and make their report no later than the second night following. The group was then to pick a more suitable campsite to the north of the previous night's unfortunate choice. They were to settle at this point, and send a pair of people each morning to the base of the peninsula until either Nick returned or ten days had pa.s.sed; in the latter event, they were to think of something else.

Nick himself had the task of contacting f.a.gin. He alone of the group was just a trifle unclear on how he was to accomplish his job. Tentatively, he planned to approach the cave village at night, and play by ear thereafter. If Swift's people had gotten into the habit of moving around at night with torches, things would be difficult. If not, it might be easy-except that his own approach would then be very noticeable. Well, he'd have to see.

The journey was normal, with enough fights to keep him in food, and he approached the cliff on the evening of the second day. He had circled far around to the west in order to come on the place from the cliff top; but even so he halted at a safe distance until almost dark. There was no telling where hunting parties might be encountered, since there was a path up the cliffs in nearly constant use by them.

As darkness fell, however, Nick felt safe in a.s.suming that all such groups would be back at their caves; and checking his fire-lighting equipment once more, he cautiously approached the cliff top. He listened at the edge for some time before venturing to push his crest over, but no informative sounds filtered up and he finally took the chance. The cliff was some three hundred fifty feet high at that point, as he well knew; and he realized that even a single spine would be quite visible from below by daylight. It might be somewhat safer now, since no fires appeared to have been lighted yet.

When he finally did look, there was nothing to see.

78 CLOSE TO CRITICAL.

There were no fires, and it was much too dark for him to see anything without them.

He drew back again to think. He was sure the village and its inhabitants lay below, and was morally certain that f.a.gin was with them. Why they had no fires going was hard to understand, but facts were facts. Perhaps it would be safe to try to sneak up to the village in the dark-but the rain would come soon, and that would be that.

Then he had another idea, found some small wood, and went to work with his fire-making tools, a drill and spindle made from tough wood. He rather expected some response from below when he got a small blaze going, since it lighted up the sky more effectively than daylight; but nothing happened until he executed the next portion of the idea, by tossing a burning stick over the edge of the cliff. Then everything happened at once.

The light showed f.a.gin, standing motionless fifty yards from the foot of the cliff. It showed an otherwise empty expanse of rock and vegetation; the people were in their caves, as usual. That, however, was only temporary.

With the arrival of the fire, a rattle of voices erupted from the caves. Evidently, if they ever slept, they weren't doing it yet. After a moment Swift's tones made themselves heard above the others.

"Get it! Get wood to it! Don't just stand there as if you were wet already!" A crowd of figures emerged from the rock and converged on the glowing twig; then they spread out again, as though they had all realized at once that no one had any wood and it would be necessary to find some. Plants were wrenched up from the ground by a hundred different hands and carried, or sometimes thrown, toward the spark.