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 remove it.

***

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 directly to the hood they were connected by a crossbar that rested on top of that jug. If either nut was tightened instead of being loosened, the bar would have bent and broken the glass. I’ll give you exactly one guess as to what would have happened then.”

“The poison liquid!”

“None other. And the double-walled hood is filled with it, too. I suggest that as soon as we have dug a deep hole in the desert the hood and container be buried and forgotten about. I doubt if the engine has many other surprises in store, but I’ll be careful as I work on it.”

“You can fix it? You know what is wrong with it?” Edipon was vibrating with joy.

“Not yet, I have barely looked at the thing. In fact one look was enough to convince that the job will be as easy as stealing krenoj from a blind man. The engine is as inefficient and clumsy in construction as your petroleum still. If you people put one tenth of the energy into research and improving your product as you do into hiding it from the competition, you would all be flying jets.”

“I forgive your insult because you have done us a service. You will now fix this engine and the other engines. A new day is breaking for us!”

“Right now it is a new night that is breaking for me,” Jason yawned. “I have two days sleep to make up. See if you can talk your sons into wiping the water off that engine before it rusts away, and when I get back I’ll see what I can do about getting it into running condition.”

X

Edipon’s good mood remained and Jason took advantage of it by extracting as many concessions as possible. By hinting that there might be more traps in the engine permission was easily gained to do all the work on the original site instead of inside the sealed and guarded buildings. A covered shed gave them protection from the weather and a test stand was constructed to hold the engines when Jason worked on them. This was of a unique design and built to Jason’s exacting specification, and since no one, including Mikah, had ever heard of or seen a test stand before Jason had his way.

The first engine proved to have a burnt-out bearing and Jason rebuilt it by melting down the original bearing metal and casting it in position. When he unbolted the head of the massive single cylinder he shuddered at the clearance around the piston; he could fit his fingers into the opening between the piston and the cylinder wall; by introducing cylinder rings he doubled the compression and power output. When Edipon saw the turn of speed the rebuilt engine gave his caroj he hugged Jason to his bosom and promised him the highest reward. This turned out to be a small piece of meat every day to relieve the monotony of the krenoj meals, and a doubled guard to make sure that his valuable property did not escape.