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to secure a demonstration of the cave people's abilities than because the answer made any difference to him. He rather expected Swift would not bother to answer, but title chief was in a very good humor—

everything had been going just as he wanted it all day. Once the group was under way, he walked beside the robot and talked quite cheerfully. Nick relayed his words, and he described in great detail the country which they were approaching and the point to which he expected the bathyscaphe to be washed. He also explained his reasons for this opinion, and the geophysicists listened, took notes, and watched with motherly care the recorders which were storing the conversation. For the first hour or two of that night there was more general happiness than the region of Altair had experienced for decades. About the only people not sharing in it were Aminadabarlee and Raeker.

Swift stopped his cavalcade after a scant two hours of rather slow travel. Night had fallen, and the rain was starting to do likewise; he set everyone to work gathering firewood, and ordered Nick to place the guard fires for a camp. Nick and his fellows obeyed without argument; Raeker suspected that they were human enough to enjoy the chance to show off their knowledge. Cave dwellers were at each of the fire sites practicing with friction drills, and one by one the piles of fuel began to glow.

For sixteen years, the lighting of the evening fires had been a signal for a forty-eight-hour period of relaxation on the Vindemiatrix, since nothing but rain ever happened at night on Tenebra. Now that was changed; discussion, sometimes verging on argument, went on full tilt. The engineers were busy festooning the outside of the shuttle with hydroferron boosters and their control lines. The diplomats wouldn't have been speaking to each other if they had followed their personal inclinations, but professional pride kept them outwardly courteous. People who knew them, however, listened to their talk very uneasily, and thought of jammed reactor control rods.

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A few enthusiasts kept watch through the robot's eyes, partly in the hope that something would happen and partly to keep Raeker company. The biologist refused to leave the observation room; he felt sure that matters were building to some sort of climax, but couldn't guess just what sort. Even during the night this feeling grew worse —particularly at such times as he happened to see or hear one of the diplomats.

Actually, Raeker was suffering badly from a sudden lack of self-confidence; he was wondering how he could possibly teach his students to make the necessary repairs on the bathyscaphe, even if they chose to listen to him. If they wouldn't, or couldn't, he didn't want to see or hear of Rich or Aminadabarlee again; he had convinced himself, quite unjustly, that his own arguments had caused them to pin their faith in him and not undertake any other steps toward a rescue.

In spite of the anxiety which let him sleep only for moments at a time, he managed to get through the night. The departure of the shuttle distracted him for a few minutes—at one point he almost convinced himself that he should go along with it, but common sense prevailed. Several times incidents occurred at the camp, and were pictured on the robot's screen, which would have made him laugh under different circumstances. The cave dwellers were not at all used to fires yet, and had some odd ideas of their properties, uses, and limitations. Several times Nick or one of the other human-educated natives had to make a rescue as someone ran blithely into the dead-air zone of a boiled-away raindrop to relight a fire.

When they finally realized that a newly destroyed raindrop was like a newly boiled lake in the early morning, some of them took to waiting a long time before venturing near the extinguished fires, so that the fuel cooled too far to let the blaze spring back to Me at the mere touch of a torch. Several of them grew worried about the fuel supply, which the experienced group had pronounced sufficient, and kept trying to persuade Swift to organize

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wood-collecting parties. Raeker could not, of course, understand these requests, but he heard a couple of his own people commenting on them with something like contempt in their voices. This made him feel somewhat better; if his pupils felt that way about the cave dwellers, perhaps they still had some attachment for their teacher.

Morning finally came without any serious incident in camp or at the bathyscaphe; and once the hill on which the camp was located ceased to be an island—it had been surrounded by the usual rainfall, but not by ocean, as far as anyone could tell—the group headed for the spot where the bathyscaphe was expected to be. This meant a walk nearly as long as that of the previous night, since Swift and his people had expected little motion on the part of the stranded machine. Raeker didn't know whether Easy had reported any drifting; he hadn't heard her voice very often during the last forty-eight hours.

Raeker himself wasn't sure how far to believe the predictions of the natives, and wasn't sure how far he wanted to believe them. If they proved right, of course, it would mean a lot to the geophysicists; but it might also mean that Easy had some grounding for her optimism about the day's events. That was good only it it was solid grounding; and Raeker could not for the life of him imagine how the girl expected the machine to be either flown, blown, or carried up to a point where the shuttle could meet it. On the few occasions that he had dozed, his sleep had been troubled by wild nightmares involving volcanoes, floaters, and forms of sea life whose shapes never became quite clear.

There was no question of how the geophysicists felt when the predicted spot was reached and the bathyscaphe found to be absent. They buzzed like a swarm of bees, hurling hypotheses at each other with scarcely time to listen to their neighbors. Aminadabarlee fainted, and constituted an absorbing first aid problem for several minutes until he revived by himself, none of die men having the Capitulation; Operation; Elevation 183

slightest idea of what to do for him. Fortunately, the ship turned up after a quarter of an hour's search exactly where it had been left the night before, which made things easier on the fathers but left many human beings and quite a few Tenebrites rather at a loss for an explanation. The sea had certainly been there; Easy had reported as much. Apparently its transporting power had been lower than expected. Some of the scientists pointed out that this was obvious; this much farther from its natural bed, the sea would be correspondingly more diluted with water. It satisfied him and some of his friends, but Rae-ker wondered how a slightly greater dilution of something which must already have been pretty pure H2O, as pure water went on Tenebra, could make that much difference. He wondered what excuse Swift was using, but couldn't find out.

Nor could he find, except by guesswork, the nature of the plan that was being executed before the robot's eyes.

Hunting parties—judging from their armament—were sent out in great numbers, each one accompanied by one of Fagin's pupils with his axe. The raft made trips to the bathyscaphe, and Swift and several others examined its surface with great care; Easy seemed to be talking to them while this went on, but Raeker and his companions couldn't hear what she said. The natives were greatly interested in the hot area at the top of the vessel, where its refrigerators pumped back overboard the calories they had drawn from the living quarters; they started to climb up the hull, by means of the numerous handholds, to examine this more closely. This act, since the craft was circular in cross section and just barely not floating, started the whole vessel rolling toward the raft; the climbers dropped back hastily. One of them fell into the lake, lost consciousness before he could grasp the paddles thrust down to him, and had to be shoved clumsily into shallow oleum by his fellows lying on the raft above him. This brought the raft itself closer to the robot, and Raeker

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was able to hear Nick remark to Betsey, "This will save a lot of time. If the teachers inside don't mind, we can roll that thing over here where we can work on it."

"We may do it whether they mind or not, if Swift gets the idea," was the reply. "We'd better ask in English first."

"Right. Let's get back out there." The two slid the raft back into the pool and paddled back toward the stranded vessel. This time Raeker knew what the conversation was about even though he couldn't hear it, and he knew how it canie out—he could see Easy nod her head in assent. It was several seconds before a frightening thought struck him, and made him call the engineering department.

"Will turning that bathyscaphe over do any harm?" he asked without preamble. "The natives are planning to roll it out of that pool."

The men at the other end exchanged glances, and then shrugged at each other.

"Not as far as I can think at the moment," one of them said. "The ship was designed to fly, and it was assumed that inverted flight might be necessary. The kids may be bumped around a bit, and anything they've left loose will tumble, but nothing vital should suffer."

"Thank goodness for that," Raeker said feelingly, and turned back to his screens. The raft was on its way back to shore, and Nick was calling something to Swift. Raeker could catch only a word or two, since the native language was being used, but he could tell easily enough what was being discussed. Swift got aboard as soon as the raft reached wading depth, loading it to capacity. Back at the bathyscaphe, he and Betsey seized the handholds on the hull and began carefully to climb, Nick staying on the raft to keep it out of the way. Raeker expected some more accidents, but the climbers showed surprising skill and co-ordination, keeping just above the liquid surface as the ship slowly rocked toward them. It was lucky that the handholds extended all over the hull; Raeker was sure

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they hadn't checked this point before starting their stunt.

A quarter turn brough the hot "exhaust area" into contact with the pool, and set the oleum bubbling furiously— or as close to bubbling as anything could come under Tenebra's atmospheric pressure. There was enough disturbance to attract the attention of the natives on the ship, but not to be visible from shore.

Two full rolls brought her to wading depth, and robbed her of enough buoyancy to make another climber necessary. Three turns brought her right side up at the shore line. A slight complication arose when the climbers dropped off and she started to roll back, and for the first time Raeker was able to make himself heard and listened to; he gave some rapid advice about placing chocks, which Nick heeded. With the hull stable and the children staring out at the robot a few yards away, Raeker thought he might learn what was going on, and he used the machine's speaker.

"Hello, Easy. We're finally together."

"Hello, Doctor. Yes, your people are here. I thought we'd be able to do without them, but they've been a big help. Are you staying to watch the rest?"

The question startled the biologist, to put it mildly.

"Staying? We're just starting to work. I'll call the engineers and have them listen in while I explain the electrolysis circuits to Nick and the others; they'd be here now, only I didn't expect the ship to be available quite so quickly. We'll find whatever wires are corroded or disconnected, and—" Easy must have started talking before he got that far, but the transmission lag delayed his hearing her interruption.

"I'm sorry, Doctor, but I'd rather not have Nick fooling with the ship's wiring. I don't understand it myself, and I don't see how he possibly can keep from making mistakes. We're going up shortly, anyway, so please don't let him get into any of those inspection ports, if they're really open." The girl spoke as pleasantly as ever, but

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there was a note of firmness which no human being who heard her could mistake. Raeker was surprised, and then indignant.

"What do you mean, you'd 'rather not' have Nick work? Who else can? If you think he's ignorant of electricity, what good will it do for you to take over—or Swift? This plan has been under way for weeks, and you can't—"

"I don't care how long it's been organized, and I can" replied the girl, still politely. "Swift will do what I ask, and Nick will do what Swift orders. We're going to try Swift's idea first; I'm sure it will work, but if it doesn't perhaps we'll think about yours again."

Raeker looked around helplessly; the kid was right. There was no way in the universe for him to enforce his will. Maybe her father—no; Rich was listening in the communication room, and the relay screen showed something like an expression of satisfaction on his face. The biologist surrendered.

"All right, Easy. Will you tell me what this plan of Swift's is? And how, if you don't trust me and Nick, you can possibly consider an ignorant savage like one of these cave dwellers worth listening to?"

"Your scientific friends do," Easy replied pointedly. "If I tell you, 'Mina's father will hear, and he1!! start thinking of things wrong with it, and that'll get Dad worried. You just watch; it won't be long now."

"How does your young friend feel about not telling his father?"

"He doesn't mind, do you, 'Mina?"

"No," piped the young Drommian. "Dad told me to do what Easy said, and besides, he was rude to her.

We'll show him!"

Raeker raised his eyebrows at this, and somehow felt a little happier about the whole matter. If someone was going to make a fool of Aminadabarlee . . .

And then Swift's plan became perfectly obvious. A

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group of hunters reappeared, towing among them the helpless form of a floater. The dangerous tentacles of the creature had been removed—it was obvious now why an axeman had accompanied each group—

and enough of its gas cells punctured so that it could be held down; but some were still intact, and their intended use could easily be seen.

The hydrogen cells of the bathyscaphe possessed, naturally, pressure-equalizing vents on the lower side of the hull. While these vents opened into the cells on the wrong side of the plastic membrane designed to prevent hydrogen and air from mixing, the other side also had a plastic tube extending down to the same vent, for relief if too much electrolytic hydrogen was run into the cell. This tube was normally held shut, or rather flat, by outside pressure; but it was perfectly possible to push another tube into it from outside, and run gas or liquid into the compartment. This the natives proceeded to do; Raeker wasn't sure of the nature of the tube, but there was nothing surprising in their being able to improvise one. There must have been a good deal of gas wasted in the transfer process, but this didn't seem to bother anyone. There were, after all, plenty of floaters,

"I see," he said through the robot after a few minutes. "But I think I see a catch.'*

"What?" Easy snapped the question with a speed which suggested she had some doubts of her own.

"That ship was computed around the lift of hydrogen. How do you know that stuff you're using will lift you high enough for your boosters to work, even if an engineer gets aboard to—"

"What makes you think this gas isn't hydrogen?'*

"What makes you think it is?"

"What else is lighter than water, in the gas state, that's likely to be found on this planet?"

"Why, lots of things, I guess—I—I don't know; I

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