Under Shar XVI, however, the three assistants had been more envied than usual among the rest of Lavon’s people, for they seemed to do very little work of any kind. They spent long hours of every day and evening talking with Shar in his chambers, poring over records, making mysterious scratch-marks on slate, or just looking at simple things about which there was no obvious mystery. Sometimes they actually worked with Shar in his laboratory, but mostly they just sat.
Shar XVI had, as a matter of fact, discovered certain rudimentary rules of inquiry which, as he explained it to Lavon, he had recognized as tools of enormous power. He had become more interested in passing these on to future workers than in the seductions of any specific experiment, the journey to the stars perhaps excepted. The Than, Tanol and Stravol of his generation were having scientific method pounded into their heads, a procedure they maintained was sometimes more painful than heaving a thousand rocks.
That they were the first of Lavon’s people to be taxed with the problem of constructing a spaceship was, therefore, inevitable. The results lay on the table: three models, made of diatom-glass, strands of algae, flexible bits of cellulose, flakes of stonewort, slivers of wood, and organic glues collected from the secretions of a score of different plants and animals.
Lavon picked up the nearest one, a fragile spherical construction inside which little beads of dark-brown lava —actually bricks of rotifer-spittle painfully chipped free from the wall of an unused castle—moved freely back and forth in a kind of ball-bearing race. “Now whose is this one?” he said, turning the sphere curiously to and fro.
“That’s mine,” Tanol said. “Frankly I don’t think it comes anywhere near meeting all the requirements. It’s just the only design I could arrive at that I think we could build with the materials and knowledge we have.”
“But how does it work?”
“Hand it here a moment, Lavon. This bladder you see inside at the center, with the hollow spyrogyra straws leading out from it to the skin of the ship, is a bouyancy tank. The idea is that we trap ourselves a big gas-bubble as it rises from the bottom and install it in the tank. Probably we’ll have to do that piecemeal. Then the ship rises to the sky on the bouyancy of the bubble. The little paddles, here along these two bands on the outside, rotate when the crew—that’s these bricks you hear shaking around inside—walks a treadmill that runs around the inside of the hull; they paddle us over to the edge of the sky. Then we pull the paddles in—they fold over into slots, like this— and, still by weight-transfer from the inside, roll ourselves up the slope until we’re out in space. When we hit another world and enter the water again, we let the gas out of the tank gradually through the exhaust tubes represented by these straws, and sink down to a landing at a controlled rate.”
“Very ingenious,” Shar said thoughtfully. “But I can foresee some difficulties. For one thing, the design lacks stability.”
“Yes, it does,” Tanol agreed. “And keeping it in motion is going to require a lot of footwork. On the other hand, the biggest expenditure of energy involved in the whole trip is going to be getting the machine up to the sky in the first place, and with this design that’s taken care of—as a matter of fact, once the bubble’s installed, we’ll have to keep the ship tied down until we’re ready to go.”
“How about letting the gas out?” Lavon said. “Will it go out through those little tubes when we want it to? Won’t it just cling to the walls of the tank instead? The skin between water and gas is pretty difficult to deform—to that I can testify.”
Tanol frowned. “That I don’t know. Don’t forget that the tubes will be large in the real ship, not just straws as they are in the model.”
“Bigger than a man’s body?” Than said.
“No, hardly. Maybe as big, though, as a man’s head.”
“Won’t work,” Than said tersely. “I tried it. You can’t lead a bubble through a pipe that small. As Lavon said, it clings to the inside of the tube and won’t be budged. If we build this ship, we’ll just have to abandon it once we hit our new world.”
“That’s out of the question,” Lavon said at once. “Putting aside for the moment the waste involved, we may have to use the ship again in a hurry. Who knows what the new world will be like? We’re going to have to be able to leave it again if it is impossible to live in.”
“Which is your model, Than?” Shar said.
“This one. With this design, we do the trip the hard way—crawl along the bottom until it meets the sky, crawl until we hit the next world, and crawl wherever we’re agoing when we get there. No aquabatics. She’s treadmill-powered, like Tanol’s, but not necessarily man-powered; I’ve been thinking a bit about using diatoms. She steers by varying the power on one side or the other; also we can hitch a pair of thongs to opposite ends of the rear axle and swivel her that way, but that would be slower and considerably less precise.”
Shar looked closely at the tube-shaped model and pushed it experimentally along the table a little way. “I like that,” he said presently. “It sits still when you want it to. With Than’s spherical ship, we’d be at the mercy of any stray current at home or in the new world—and for all I know there may be currents of some sort in space, too, gas currents perhaps. Lavon, what do you think?”
“How would we build it?” Lavon said. “It’s round in cross-section. That’s all very well for a model, but how do you make a really big tube of that shape that won’t fall in on itself?”
“Look inside, through the front window,” Than said. “You’ll see beams that cross at the center, at right angles to the long axis. They hold the walls braced.”
“That consumes a lot of space,” Stravol objected. By far the quietest and most introspective of the three assistants, he had not spoken until now since the beginning of the conference. “You’ve pretty well got to have free passage back and forth inside the ship. How are we going to keep everything operating if we have to be crawling around beams all the time?”
“All right, come up with something better,” Than said, shrugging.
“That’s easy. We bend hoops.”
“Hoops!” Tanol said. “On that scale? You’d have to soak your wood in mud for a year before it would be flexible enough, and then it wouldn’t have the strength you’d need.”
“No, you wouldn’t,” Stravol said. “I didn’t build a ship-model, I just made drawings, and my ship isn’t as good as Than’s by a long distance. But my design for the ship is also tubular, so I did build a model of a hoop-bending machine—that’s it on the table. You lock one end of your beam down in a heavy vise, like so, leaving the butt sticking out the other side. Then you tie up the other end with a heavy line, around this notch. Then you run your rope around a windlass, and five or six men wind up the windlass, like so. That pulls down the free end of the beam until the notch engages with this key-slot, which you’ve pre-cut at the other end. Then you unlock the vise, and there’s your hoop; for safety you might drive a peg through the joint to keep the thing from springing open unexpectedly.”
“Wouldn’t the beam you were using break after it had bent a certain distance?” Lavon asked.
“Stock timber certainly would,” Stravol said. “But for this trick you use green wood, not seasoned. Otherwise you’d have to soften your beam to uselessness, as Tanol says. But live wood will flex enough to make a good, strong, single-unit hoop—or if it doesn’t, Shar, the little rituals with numbers that you’ve been teaching us don’t mean anything after all!”
Shar smiled. “You can easily make a mistake in using numbers,” he said.