Hal Clement - Heavy Planet

“We might as well,” answered Beetchermarlf. “It seems a pity that that’s the only use we can get out of all that power. Four of those things can push the Kuembly around on level ground and I once heard a human being say that one could do it if it could get traction. That certainly could chip ice for us if we could find a way to apply it.? “We can take the power box out easily enough, but what we’d do afterward beats me. The units put out electric current as one choice, but I don’t see how we could shock the ice away. The mechanical torque you can get from them works only on the motor shafts.”

“We’d be more likely to shock ourselves away if we used the current. I don’t know very much about electricity, it was mostly plain mechanics I got in the little time I was at the College, but I know enough of it can kill. Think of something else.” Takoorch endeavored to comply. Like his young companion, he had had only a short period of exposure to alien knowledge; both had volunteered for the Dhrawn project in preference to further classwork. Their knowledge of general physics might have compared fairly well with that of Benj Hoffman when he was ten or twelve years old. Neither was really comfortable in thinking about matters for which no easily visualized model could be furnished. They were not, however, lacking in the ability to think abstractly. Both had heard of heat as representing a lowest common denominator of energy, even if they didn’t picture it as random particle motion. It was Beetchermarlf who first thought of another effect of electricity. “Tak! Remember the explanations we got about not putting too much power into the trucks until the cruiser got moving? The humans said it was possible to snap the treads or damage the motors if we tried to accelerate too faust.”

“That’s right. Quarter power is the limit below a hundred cables per hour.”

“Well, we have the power controls here where we can get at them, and those motors certainly aren’t going to turn. Why not just power this truck and let the motor get as hot as it wants to?”

“What makes you think it will get hot? You don’t know what makes those motors go any more than I do. They didn’t say it would make them hot, just that it was bad for them.”

“I know, but what else could it be? You know that any sort of energy that isn’t used up some other way turns into heat.”

“That doesn’t sound quite right, somehow,” returned the older sailor. “Still, I guess anything is worth trying now. They didn’t say anything about the motor’s wrecking the rest of the ship too; if it ruins us, well, we won’t be much worse off.” Beetchermarlf paused; the thought that he might be endangering the Kwembly hadn’t crossed his mind. The more he thought of it, the less he felt justified in taking the chance. He looked at the relatively tiny power unit nestling between the treads of the nearby truck, and wondered whether such a minute thing could really be a danger to the huge bulk above them. Then he remembered the vastly greater size of the machine which had brought him and his fellows to Dhrawn and realized that the sort of power which could hurl such immense masses through the sky was not to be handled casually. He would never be afraid to use such engines, since he had been given a chance to become familiar with their normal and proper handling; but deliberately misusing one of them was a different story. “You’re right,” he admitted somewhat inaccurately. Takoorch had been, after all, willing to take the chance. “We’ll have to work it differently. Look, if the tracks are free to turn, then we can’t damage the motor or the power box and just stirring up water will warm it.”

“You think so? I remember hearing something like that, but if I can’t break up this ice with my own strength it’s hard to see how simply stirring water is going to do it. Besides, the trucks aren’t free; they’re on the bottom with the Kwembly’ s weight on them.”

“Right. You wanted to dig. Start moving rocks; that ice is getting close.” Beetchermarlf set the example and began prying the rounded cobbles from the edges of the treads. It was a hard job even for Mesklinite muscles. Smooth as they were, the stones were tightly packed; furthermore when one was moved, there was not too much room in which to put it. The stones under the treads, which were the ones which really had to be shifted, could not even be reached until those at the sides were out of the way. The two labored furiously to clear a ditch around the truck. They were frightened at the time it took. When the ditch was deep enough, they tried to pry stones from under the treads and this was even more discouraging. The Kwembly had a mass of about two hundred tons. On Dhrawn, this meant a weight of sixteen million pounds to distribute among the fifty-six remaining trucks: the mattress did a good job of distributing. Three hundred thousand pounds, even if it is a rather short three hundred thousand, is too much even for a Mesklinite, whose weight, even at Mesklin’s pole, is little over three hundred. It is a great deal even for some eight square feet of caterpillar tread. If Dhrawn’s gravity had not done an equally impressive job of packing its surface materials, the Kwembly and her sister vehicles would probably have sunk to their mattresses before travelling a yard. In other words, the rocks under the tread were held quite firmly. Nothing the two sailors could do would move one of them at all. There was nothing to use as a lever; their ample supplies of spare rope were useless without pulleys; their unaided muscles were pitifully inadequate — a situation still less familiar to them than to races whose mechanical revolution lay a few centuries in the past. The approaching ice, however, was a stimulus to thought. It could also have been a stimulus to panic but neither of the sailors was prone to that form of disintegration. Again, it was Beetchermarlf who led. “Tak, get out from under. We can move those pebbles. Get forward; they’re going to go the other way.” The youngster was climbing the truck as he spoke, and Takoorch grasped the idea at once. He vanished beyond the next-forward truck without a word. Beetchermarlf stretched out along the main body of the drive unit, between the treads. In this foot-wide space, beneath and in front of him, was the recess which held the power converter. This was a rectangular object about the same size as the communicators, with ring-tipped control rods projecting from its surface and guide loops equipped with tiny pulleys at the edges. Lines for remote handling from the bridge were threaded through some of the guides and attached to the rings but the helmsman ignored them. He could see little, since the lights were still on the bottom several feet away and the top of the truck was in shadow; however, he did not need sight. Even clad in an air suit he could handle these levers by touch. Carefully he eased the master reactor control to the “operate” position; then, even more gingerly, started the motors forward. They responded properly; the treads on either side of him moved forward, and a clattering of small, hard objects against each other became audible for a moment. Then this ceased, and the treads began to race. Beetchermarlf instantly cut off the power, and crawled off the truck to see what had happened. The plan had worked, just as a computer program with a logic error works: there is an answer forthcoming but not the one desired. As the helmsman had planned, the treads had scuffed the rocks under them backward; but he had forgotten the effect of the pneumatic mattress above. The truck had settled under its own weight and the downward thrust of the gas pressure until the chassis between the treads had met the bottom. Looking up, Beetchermarlf could see the bulge in the mattress where the entire drive unit had been let down some four inches. Takoorch appeared from his shelter and looked the situation over, but said nothing. There was nothing useful to say. Neither of them could guess how much more give there was to the mattress, and how much farther the truck would have to be let down before it would really hang free, though they knew the details of the Kwemb/y’ s construction. The mattress was not a single gas bag but was divided into thirty separate cells, having two trucks in tandem attached to each. The helmsmen knew the details of the attachment-boch had just spent many hours repairing the assemblies — but even the recent display of the Kwembly ’s underside with the weight off nearly all the trucks left them very doubtful about how far any one truck could extend by itself. “Well, back to stone lugging,” remarked Takoorch as he worked his nippers under a pebble. “Maybe these have been jarred loose now; otherwise it’s going to be awkward, getting at them only from the ends.”