Hal Clement: Heavy Planet

“The Deedee came in an hour ago, and is gone again. There’s too much for that machine to do. It was bad enough when we lost the Elsh, and with Kabremm and his Gwelf overdue things are piling up. I hope we find him. Maybe the Kalliff will turn up something; he was supposed to be scouting a route to get her to Don’s camp, so maybe one of Kenanken’s scouts will spot him. He’s less than a day overdue, so there’s still a chance …”

“And with all this, you say we’re ahead?” cut in Guzmeen. “Sure. Remember, the whole aim of the Esket act was to persuade the human beings to let us use space ships. The self-support business was incidental, though useful. We expected to work the local-life myth up to a major menace before we could persuade Aucoin to let us fly, and spend months building up to it. We’re far ahead on time, and haven’t lost very much, the base at the Esket site, of course, and the Elsh and its crew, and just possibly Kabremm and his.”

“But even Kabremm and Karfrengin aren’t exactly expendable. There aren’t very many of us. If Dondragmer and his crew don’t keep alive until the Kalliff reaches them, we’ll have taken a really serious loss; at least our dirigible crews weren’t our scientists and engineers.”

“Don’s in no real danger. They can always be picked up by Beetchermarlf in the human space ship — I mean our space ship.”

“And if anything goes wrong with that operation we’re out not only our only space ship but our only space pilots.”

“Which suggests to me,” Barlennan said thoughtfully, “that we should try to regain some lost ground. As soon as the Kwembly is ready she should start hunting a suitable place and start replacing the Esket settlement. Don’s scientists should have little trouble finding a good location; Dhrawn seems to be rich in metal ores. Maybe we should have him search closer to here so that communication will be quicker, though. “We’ll have to build more dirigibles; the one we have left isn’t nearly enough for the work. Maybe we ought to design bigger ones.”

“I’ve been wondering about that,” a technician who had been listening silently up to this point spoke up. “Do you suppose that it would be smart to find out more, tactfully, of course, from the humans about dirigibles? We’ve never discussed the subject with them; they taught you about balloons years ago, and some of our own people got the idea of using the human power sources with them. We don’t know if they ever used them at all. Maybe it isn’t just bad luck that we’ve lost two out of our three in such a short time. Maybe there’s something fundamentally wrong with the whole idea.” The commander gave a gesture of impatience. “That’s silly. I didn’t try to pick up a complete scientific education from the aliens, since it was obviously going to take too long; but one thing I did gather was that the underlying rules are essentially simple. Once the humans started concentrating on basic rules, they went from sailing ships to space ships in a couple of hundred years. Balloons, powered or not, are simple devices; I understand them perfectly myself. Putting an engine aboard doesn’t change that; the same rules have to be working.” The technician eyed his commander thoughtfully, and thought briefly of electron tubes and television circuits before replying. “I suppose,” he said thoughtfully, “that a piece of a tent being blown away by the gale, and a ship being tacked into the wind, are also examples of the same rules at work.? Barlennan didn’t want to give an affirmative answer, but he could find nothing better. He was still trying to shrug off the technician’s remark, but only succeeding in growing more and more doubtful of his situation, some twenty hours later when a messenger called him to the communication room. As soon as he entered, Guzmeen spoke briefly into a microphone; a minute later, a human face which neither of them recognized appeared on the screen. “I am Ib Hoffman, Easy’s husband and Benj’s father,” the stranger began without preamble. “I’m speaking to you two, Barlennan and Dondragmer, alone. The rest of the observing crew here are concentrating on a new emergency involving one of the cruisers. I’m using your language as best I can, with my wife standing by; she knows what I want to say, and will correct me if I slip too badly. I have decided that it is time to clear up some misunderstandings, but I don’t plan to tell everyone here about them; you’ll see why before I finish, if you don’t already. I’m bothered mostly because I hate to call anyone a liar in any language. “First, Barlennan, my hearty congratulations. I am just about certain that when we turned the barge over to a Mesklinite pilot we fulfilled one of your chief plans, probably well before you meant or expected it to mature. That’s fine. I wanted that to happen. Probably you want to make interstellar flights on your own later on, too; that’s also fine with me. I’ll help. “You seem to feel that many or most human beings would try to thwart you in this, and I have to admit that some would, though I think we have the most effective one under control now. You can’t be sure that I’m being sincere now, for that matter; you’re tricky enough yourself to expect it of other people. Too bad. How much you believe of what I say is beyond my control; I still have to say it. “I don’t know how much of the basic situation you set up, but I can guess. I’m nearly sure the Esket disappearance was not genuine. I’m uncertain of the real status of the Kwembly. You probably know more of Dhrawn than you’ve reported. I won’t say I don’t care, because I do; we’re here to learn as much as possible about Dhrawn, and what you don’t tell us is a loss to the project. I can’t threaten you with penalties for breach of contract, since I’m not completely certain you’ve broken it and am in no position to carry out threats. And in any case have less than no desire to even make threats. I do want to persuade you, though, that it will be better for both of us if we do without secrets. We’re at a point where anything less than complete frankness is likely to cost us a lot and cost you everything. To make that point, I’m going to tell you a story. “You know that human beings breathe oxygen much as you do hydrogen, though being so much larger we need a more complicated pumping system to get it through our bodies. Because of the details of that system, we suffocate if deprived of gaseous, free oxygen within a certain rather narrow range of pressures. “About three quarters of Earth is covered by water. We cannot breathe under water without artificial equipment, but the use of such equipment is a common human sport. It consists essentially of a tank of compressed air and a valve system which releases the air to our breathing system as needed; simple and obvious. “Six of our years ago, when Benj was eleven years old, he made such a device, designing it himself with my assistance. He made the pressure tank and regulator, using ordinary fabricating equipment such as may be found in most home workshops, just as he had made more complex things such as small gas turbines. He tested the parts with my help; they worked perfectly. He calculated how long the air in the tank would last him, and then tested the whole assembly under water. I went along as a matter of common-sense safety, using a commercial diving device. “I am sure you know the principles of hydrostatics and the gas laws; at least, Easy has given me words for them in your language. You can see that at a certain depth, a lungful of air would have only half its volume at the surface. Benj knew this too, but reasoned that it would still be a lungful as far as oxygen content was concerned, so that a one-hour tank would be a one-hour tank regardless of depth, as long as tank pressure was above that of the water. “To make a long story short, it didn’t. He ran out of air in less than a third of the calculated time, and I had to make an emergency rescue. Because of the quick pressure change and some human peculiarities which you don’t seem to share, he was very nearly killed. The trouble turned out to be that the human breathing rate is controlled, not by the oxygen in our blood, but by the carbon dioxide, one of the waste products. To maintain a normal equilibrium of that, we have to run normal volumes of air through our lungs, regardless of oxygen content or total pressure; hence, an hour’s air supply at normal pressure is only half an hour thirty-three feet under water, a third of an hour at sixtysix, and so on. “I don’t want to insult anyone’s intelligence by asking if he understands my point, but I’d like some comment from both of you on that story.” The answers were interesting, both in nature and arrival time. Barlennan’s popped from the speaker with very little more than light-travel delay; Dondragmer’s came much, much later, and did not overlap with his commander’s. “It is obvious that incomplete knowledge can lead to mistakes,” said Barlennan, “but I don’t see why that is especially applicable to the present case. We know that our knowledge can’t be complete, and that our work here is dangerous for that reason. We have always known it. Why emphasize the point now? I’d much rather hear your report on the cruiser you say is in trouble. You make me suspect that you are leading up gently to the information that I have lost another cruiser because of something its designing engineers didn’t know. Don?t worry, I won?t blame you for that. None of us could foresee everything.? Ib smiled sourly at the revelation of yet another human characteristic. “That’s not just what I had in mind, Commander, though there are valid aspects to what you have just said. I’d like to wait for Dondragmer’s answer before I say any more, though.” It was another full minute, a slightly strained one, before the voice of the Kwembly’s captain arrived. “Your account is plain enough and you would probably have been briefer had you not meant to imply more. I suspect that your key point is not so much that your son got into trouble through ignorance, but that he did so even under your experienced adult supervision. I would take the implication to be that even though you aliens do not claim omniscience or omnipotence, we are in a certain amount of danger here no matter how closely you supervise and assist us, and we are adding unnecessarily to our danger any time we act on our own, like the student chemist who experiments on his own.” Dondragmer had spent much more time at the College than had his commander. “Right. Just what I meant,” said Ib. “I can’t …”