the knife he covered the bottom in a regular pattern. The depth of the metal was uniformly deep except in two spots where he found irregularities, they were on the midline of the rectangular base, and equidistant from the ends and sides. Picking and scraping he uncovered two familiar looking shapes each as big as his head.
“Mikah. Get down in this hole and look at these things. Tell me what you think they are.”
Mikah scratched his beard. “They’re still covered with this metal, I can’t be sure — ”
“I’m not asking you to be sure of anything — just tell me what they make you think of.”
“Why… big nuts of course. Threaded on the ends of bolts. But they are so big — ”
“They would have to be if they hold the entire metal case on. I think we are getting very close now to the mystery of how to open the engine — and this is the time to be careful. I still can’t believe it is as easy as this to crack the secret. I’m going to whittle a wooden template of the nut, then have a wrench made. While I’m gone you stay down here and pick all the metal off the bolt and out of the screw threads. I can put off doing it while we think this thing through, but sooner or later I’m going to have to take a stab at turning one of those nuts. And I find it very hard to forget about that mustard gas.”
Making the wrench put a small strain on the local technology and all of the old men who enjoyed the title of Masters of the Still went into consultation over it. One of them was a fair blacksmith and after a ritual sacrifice and a round of prayers he shoved a bar of iron into the charcoal and Jason pumped the bellows until it glowed white hot. With much hammering and cursing it was laboriously formed into a sturdy open-end wrench with an offset head to get at the countersunk nuts. Jason made sure that the opening was slightly undersized, then took the untempered wrench to the work site and filed the jaws to an exact fit. After being reheated and quenched in oil he had the tool that he hoped would do the job.
Edipon must have been keeping track of the work progress because he was waiting near the engine when Jason returned with the completed wrench.
“I have been under,” he announced, “and have seen the nuts that the devilish Appsalanoj have concealed within solid metal. Who would have suspected! It still seems to me impossible that one metal could be hidden within another, how could that be done?”
“Easy enough. The base of the assembled engine was put into a form and the molten covering metal poured into it. It must have a much lower melting point than the steel of the engine so there would be no damage. They just have a better knowledge of metal technology in the city and counted on your ignorance.”
“Ignorance! You insult — ”
“I take it back. I just meant they thought they could get away with the trick, and since they didn’t they are the stupid ones. Does that satisfy you?”
“What do you do next?”
“I take off the nuts and when I do there is a good chance that the poison-hood will be released and can simply be lifted off.”
“It is too dangerous for you to do, the fiends may still have other traps ready when the nut is turned. I will send a strong slave to turn them while we watch from a distance, his death will not matter.”
“I’m touched by your concern for my health, but as much as I would like to take advantage of the offer, I cannot. I’ve been over the same ground and reached the reluctant conclusion that this is one job of work that I have to do myself. Taking off those nuts looks entirely too easy, and that’s what makes me suspicious. I’m going to do it and look out for any more trickery at the same time — and that is something that only I can do. Now I suggest you withdraw with the troops to a safer spot.”
There was no hesitation about leaving, footsteps rustled quickly on the sand and Jason was alone. The leather walls flapped slackly in the wind and there was no other sound. Jason spat on his palms, controlled a slight shiver and slid into the pit. The wrench fitted neatly over the nut, he wrapped both hands around it and, bracing his leg against the pit wall, began to pull.
And stopped. Three turns of thread on the bolt projected below the nut, scraped clean of metal by the industrious Mikah. Something about them looked very wrong but he didn’t know quite what.
“Mikah,” he shouted, and had to call loudly two more times before his assistant poked his head tentatively around the screen. “Nip over to the petroleum works and get me one of their bolts threaded with a nut, any size, it doesn’t matter.”
Jason warmed his hands by the stove until Mikah returned with the oily bolt, then waved him out to rejoin the others. Back in the pit he held it up next to the protruding section of Appsalan bolt and chortled with joy. The threads on the angle bolt were canted at a slightly different angle: where one ran up, the other ran down. The Appsalan threads had been cut in reverse, with a lefthand thread.
Throughout the galaxy there existed as many technical and cultural differences as there were planets, yet one of the few things they all had in common, inherited from their terrestrial ancestors, was a uniformity of thread. Jason had never thought about it before, but when he mentally ran through his experiences on different planets he realized that they were all the same. Screws went into wood, bolts went into threaded holes and nuts all went onto bolts when you turned them with a clockwise motion. Counterclockwise removed them. In his hand was the crude D’zertano nut and bolt, and when he tried it it moved in the same manner. But the engine bolt did not work that way — it had to be turned clockwise to
Dropping the nut and bolt he placed the wrench on the massive engine bolt and slowly applied pressure in what felt like the completely wrong direction, as if he were tightening not loosening. It gave slowly, first a quarter then a half turn. And bit by bit the projection threads vanished until they were level with the surface of the nut. It turned easily now and within a minute it fell into the pit — he threw the wrench after it and scrambled out. Standing at the edge he carefully sniffed the air, ready to run at the slightest smell of gas. There was nothing.
The second nut came off as easily as the first and with no ill effects. Jason pushed a sharp chisel between the upper case and the baseplate where he had removed the solder, and when he leaned on it the case shifted slightly, held down only by its own weight.
From the entrance to the enclosure he shouted to the group huddled in the distance. “Come on back — this job is almost finished.”
They all took turns at sliding into the pit and looking at the projecting bolts and made appreciative sounds when Jason leaned on the chisel and showed how the case was free.
“There is still the little matter of taking it off,” he told them, “and I’m sure that grabbing and heaving is the wrong way. That was my first idea too, but the people who assembled that thing had some bad trouble in store for anyone who tightened those nuts instead of loosening them. Until we find out what that is we are going to tread very lightly. Do you have any big blocks of ice around here, Edipon? It is winter now, isn’t it?”
“Ice? Winter?” Edipon mumbled, caught off guard by the change of direction, rubbing abstractedly at the reddened tip of his prominent nose. “Of course it is winter. Ice, there must be ice at the higher lakes in the mountain, they are always frozen at this time of the year. But what do you want ice for?”
“You get it and I’ll show you. Have it cut in nice flat blocks that I can stack. I’m not going to lift the hood — I’m going to drop the engine out from underneath it!”
By the time the slaves had brought the ice down from the distant lakes Jason had rigged a strong wooden frame flat on the ground around the engine and pushed sharpened metal wedges under the hood, then had secured the wedges to the frame. Now, if the engine was lowered into the pit, the hood would stay above supported by the wedges. The ice would take care of this. Jason built a foundation of ice under the engine then slipped out the supporting bars. Now as the ice slowly melted the engine would be gently lowered into the pit.
The weather remained cold and the ice refused to melt until Jason had the pit ringed with smoking oil stoves. Water began to run down into the pit and Mikah went to work bailing it out, while the gap between the hood and the baseplate widened. The melting continued for the rest of the day and almost all of the night. Red-eyed and exhausted Jason and Mikah supervised the soggy sinking and when the D’zertanoj returned at dawn the engine rested safely in a pool of mud on the bottom of the pit: the hood was off.
“They’re tricky devils over there in Appsala, but Jason dinAlt wasn’t born yesterday,” he exulted. “Do you see that crock sitting there on top of the engine,” he pointed to a sealed container of thick glass the size of a small barrel, filled with an oily greenish liquid; it was clamped down tightly with padded supports. “That’s the booby trap. The nuts I took off were on the threaded ends of two bars that held the hood on, but instead of being fastened
