Hanging by a Thread

by Randall Garrett

inserted it into thefemale plug. "Hard to see those threads with all the tubes blockingthat plug," he said offhandedly.

  Hull said: "Captain, did you know that the refrigerator is off?"

  "Yes," said Atef Al-Amin absently. "It isn't connected to theemergency circuits. Wastes too much energy. What do you find, Mr.Kelvin?"

  After a second's silence, Jayjay said: "Let me check once more." Hewas running the tip of the toothpick across the threads in the femaleplug, counting as he did so. "Uh-huh," he said finally, "just as Ithought. There's one less thread in the female plug. The male plug isstopped before it can make contact. There's a gap of about a tenth ofan inch when the coupling is screwed up tight."

  "Let me see," Smith said. He took the toothpick and went through thesame operation. "You're right," he said ruefully, "the female plug isfaulty. We'll have to use one of the other screamers."

  "Right," said Jayjay.

  Wrong, said Fate. Or the Powers That Be, or the Fallibility of Man,whatever you want to call it.

  Every screamer unit suffered from the same defect.

  * * * * *

  "I don't understand it!" A pause. "It's impossible! Those units weretested!"

  For the first time in his life, Captain Atef Abdullah Al-Amin allowedhis voice to betray him.

  Arabic is normally spoken about half an octave above the normal toneused for English. And, unlike American English, it tends to waver upand down the scale. Usually, the captain spoke English in the flat,un-accented tones of the Midwest American accent, and spoke Arabic inthe ululating tones of the Egyptian.

  But now he was speaking English with an Egyptian waver, not realizingthat he was doing it.

  "How could it happen? It's ridiculous!"

  The captain, his maintenance officer, and Jeffry Hull were clusteredaround the screamer unit in the lounge. Off to one side, Jayjay Kelvinheld a deck of cards in his hands and played a game of patience called"transportation solitaire." His eyes didn't miss a play, just as hisears didn't miss a word.

  He pulled an ace from the back of the deck and flipped it to thefront.

  "You said the screamers had been checked," Jeffry Hull saidaccusingly. "How come they _weren't_ checked?"

  "They _were_!" Al-Amin said sharply.

  "Sure they were," Smith added. "I watched the check-off. There wasnothing wrong then."

  "Meanwhile," Hull said, the acid bite of fear in his voice, "we haveto sit here and wait for the Interplanetary Police to find us by pureluck."

  The captain should have let Hull cling to the idea that the IP couldfind the _Persephone_, even if no signal was sent. But the captain wasalmost as angry and flustered as Hull was.

  "Find us?" he snapped. "Don't be ridiculous! We won't even be misseduntil we're due at Styx, on Pluto, nine days from now. By that time,we'll be close to two billion miles beyond the orbit of Pluto. We'llnever be found if we wait 'til then. Something has to be done _now_!"He looked at his Maintenance Officer. "Smith, isn't there some way tomake contact between those two plugs?"

  "Sure," Smith said bitterly. "If we had the tools, it would be ducksoup. All we'd have to do is trim down the male plug to fit thefemale, and we'd have it. But we don't have the tools. We've got acouple of files and a quarter-horsepower electric drill with one bit.Everything else was in the tool compartment--which is long gone, withthe engine room."

  "Can't you ... uh, what do you call it? Uh ... jury-something--"Hull's voice sounded as though he were forcing it to be calm.

  "Jury-rig?" Smith said. "Yeah? With what? Dammit, we haven't got anytools, and we haven't got any materials to work with!"

  "Can't you just use a wrench to tighten them more?" Hull askedhelplessly.

  Smith said a dirty word and pushed himself away from the screamer unitto glower at an unresisting wall.

  "No, Mr. Hull, we couldn't," said Captain Al-Amin with restrainedpatience. "That would strip the threads. If the electrical contactwere made at the same time, the high-pressure oxygen-hydrogen flowwould spark off, and we'd get a big explosion that would wreckeverything--including us." Then he muttered to himself: "I still don'tsee how it could happen."

  Jayjay Kelvin pulled a nine of spades from the back of the deck to thefront. It matched the four of spades that had come three cardsbefore. Jayjay discarded the two cards between the spades. "Youdon't?" he asked. "Didn't you ever hear that the total is greater thanthe sum of its parts?"

  "What?" Captain Al-Amin sounded as though he'd been insulted--inArabic. "What are you talking about, Mr. Kelvin?"

  "I'm talking about the idiocy of the checking system," Jayjay saidflatly. "Don't you see what they did? Don't you see what happened?Each part of a screamer has to be checked separately, right?"

  Al-Amin nodded.

  "Why? Because the things burn out if you check them as a completeunit. It's like checking a .50 caliber cartridge. The only way you cancheck a cartridge is to shoot it in a gun. If it works, then you knowit works. Period. The only trouble is that you've wasted thecartridge. You know that _that_ one is good, but you've ruined it.

  "Same way with a screamer. If you test it as a unit, you'll ruin it.So you test it a part at a time. All the parts check out nicelybecause the test mechanisms are built to check each part."

  Smith squinted. "Well, sure. If you check out the whole screamer,you'll ruin it. So what?"

  "So suppose you were going to check out a cartridge," Jayjay said."You don't fire it; you check each part separately. You check thebrass case. It's all right; the tests show that it won't burst underfiring pressure. You check the primer; the tests show that it willexplode when hit by the gun's hammer. You check the powder; the testsshow that the powder will burn nicely when the flame from the primerhits it. You check the bullet; the tests show that the slug will beexpelled at the proper velocity when the powder is ignited.

  "So you assume that the cartridge will function when fired.

  "But will it?"

  "Why wouldn't it?" Smith asked.

  "Because the flame from the exploding primer can't reach the powder,that's why!" Jayjay snapped. "Some jerk has redesigned the primer sothat the flame misses the propellant!"

  "How could that happen?" Hull asked blankly.

  "How? Because Designer _A_ decided that the male plug on the screamershould have one more turn on its threads, but he forgot to tellDesigner _B_, who designs the female plug, that the two should match.The testing equipment is designed to test each part, so each parttests out fine. The only trouble is that the thing doesn't test out asa whole."

  * * * * *

  Captain Al-Amin nodded slowly. "That's right. The test showed that theoxyhydrogen section worked fine. It showed that the starter workedfine. It showed that the radiowave broadcaster worked fine. But itdidn't show that they'd work together."

  Smith said a short, five-letter word. It was French; the Anglo-Saxonequivalent has only four letters. "What good does all this theorizingdo us?" he added. "The question is: How do we fix the thing?"

  "Well, can't you put another turn on the thread?" Hull asked.

  "Oh, sure," Smith said sarcastically. "You give me a lathe and theproper tools, and I'll make you all the connections you want. Hell, ifI had the proper tools, I could turn us out a new spaceship, and wecould all go home in comfort."

  "Couldn't you drill out the metal with that drill?" Hull askedplaintively.

  "No!" Smith said harshly. "How do you expect me to get a quarter-inchbit into a space less than a sixteenth of an inch in diameter?"

  Hull wasn't used to machinist's terms. "How big is an inch?"

  "Two point five four oh oh oh five centimeters," Smith said in a nastytone of voice. "Does that help you any?"

  "I'm just trying to help!" Hull snapped. "You've got no call to getsarcastic with me!"

  Smith said the French word again.

  "Enough!" the captain barked. "Smith, control your tongue! That sortof thing won't help us." He jerked his head around. "Mr.
Kelvin, doyou have any suggestions?"

  Jayjay played another card. "No. Not yet. I'm thinking."

  "Smith? Any ideas?" The tone of the Arab's voice left no doubt that hemeant business.

  "No, sir. Without a properly equipped machine shop, there's