"Well, for Heaven"s sake do the best you can," Fitzhugh said in a worried voice. "This beat is shaking Snook.u.ms" brain. G.o.d knows what damage it may do unless it"s stopped within a very few minutes!"

"I"ll do the best I can," said Mike the Angel carefully. "So will every man in my crew. But about all anyone can do is wish us luck and let us work."

"Yes," said Dr. Fitzhugh slowly. "Yes. I understand. Thank you, Commander."

Mike the Angel nodded curtly and went back to work.

Things weren"t bad enough as they were. They had to get worse. The _Brainchild_ had been built too fast, and in too unorthodox a manner.

The steady two-cycle throb did more damage than it would normally have done aboard a non-experimental ship.

Twelve minutes after the throb started, a feeder valve in the pre-induction energy chamber developed a positive-feedback oscillation that threatened to blow out the whole pre-induction stage unless it was damped. The search for the out-of-phase external field tubes had to be dropped while the more dangerous flaw was tackled.

Multhaus plugged in an emergency board and began to compensate by hand while the others searched frantically for the trouble.

Hand compensation of feeder-valve oscillation is pure intuition; if you wait until the meters show that damping is necessary, it may be too late--you have to second-guess the machine and figure out what"s coming _before_ it happens and compensate then. You not only have to judge time, but magnitude; overcompensation is ruinous, too.

Multhaus, the Chief Powerman"s Mate, sat behind the emergency board, a vernier dial in each hand and both eyes on an oscilloscope screen. His red, beefy face was corded and knotted with tension, and his skin glistened with oily perspiration. He didn"t say a word, and his fingers barely moved as he held a green line reasonably steady on that screen.

Mike the Angel, using unangelic language in a steady, muttering stream, worked to find the circuit that held the secret of the ruinous feedback tendency, while other powermen plugged and unplugged meter jacks, flipped switches, and juggled tools.

In the midst of all this, in rolled Snook.u.ms.

Whether Snook.u.ms knew that his own existence was in danger is problematical. Like the human brain, his own had no pain or sensory circuits within it; in addition, his knowledge of robotics was small--he didn"t even know that his brain was in Cargo Hold One. He thought it was in his head, if he thought about it at all.

Nonetheless, he knew _something_ was wrong, and as soon as his "curiosity" circuits were activated, he set out in search of the trouble, his little treads rolling at high speed.

Leda Crannon saw him heading down a companionway and called after him.

"Where are you going, Snook.u.ms?"

"Looking for data," answered Snook.u.ms, slowing a little.

"Wait! I"ll come with you!"

Leda Crannon knew perfectly well what effect the throb might have on Snook.u.ms" brain, and when something cracked, she wanted to see what effect it might have on the behavior of the little robot. Like a hound after a fox, she followed him through the corridors of the ship.

Up companionways and down, in and out of storerooms, staterooms, control rooms, and washrooms Snook.u.ms scurried, oblivious to the consternation that sometimes erupted at his sudden appearance. At certain selected spots, Snook.u.ms would stop, put his metal arms on floors and walls, pause, and then go zooming off in another direction with Leda Crannon only paces behind him, trying to explain to crewmen as best she could.

If Snook.u.ms had been capable of emotion--and Leda Crannon was not as sure as the roboticists that he wasn"t--she would have sworn that he was having the time of his life.

Seventeen minutes after the throb had begun, Snook.u.ms rolled into Power Section and came to a halt. Something else was wrong.

At first he just stopped by the door and soaked in data. Mike"s muttering; the clipped, staccato conversation of the power crew; the noises of the tools; the deep throb of the ship itself; the underlying oddness of the engine vibrations--all these were fed into his microphonic ears. The scene itself was transmitted to his brain and recorded. The cryotronic maze in the depths of the ship chewed the whole thing over. Snook.u.ms acted.

Leda Crannon, who had lost ground in trying to keep up with Snook.u.ms"

whirling treads, came to the door of Power Section too late to stop the robot"s entrance. She didn"t dare call out, because she knew that to do so would interrupt the men"s vital work. All she could do was lean against the doorjamb and try to catch her breath.

Snook.u.ms rolled over to the board where Multhaus was sitting and watched over his shoulder for perhaps thirty seconds. The crewmen eyed him, but they were much too busy to do anything. Besides, they were used to his presence by this time.

Then, in one quick tour of the room, Snook.u.ms glanced at every meter in the place. Not just at the regular operating meters, but also at the meters in the testing equipment that the power crew had jack-plugged in.

Mike the Angel looked around as he heard the soft purring of the caterpillar treads. His glance took in both Snook.u.ms and Leda Crannon, who was still gasping at the door. He watched Leda for the s.p.a.ce of three deep breaths, tore his eyes away, looked at what Snook.u.ms was doing, then said: "Get him out of here!" in a stage whisper to Leda.

Snook.u.ms was looking over the notations on the meter readings for the previous few minutes. He had simply picked them up from the desk where one of the computermen was working and scanned them rapidly before handing them back.

Before Leda could say anything, Snook.u.ms rolled over to Mike the Angel and said: "Check the lead between the 391-JF and the big DK-37. I think you"ll find that the piping is in phase with the two-cycle note, and it"s become warped and stretched. It"s about half a millimeter off--plus or minus a tenth. The pulse is reaching the DK-37 about four degrees off, and the gate is closing before it all gets through. That"s forcing the regulator circuit to overcompensate, and...."

Mike didn"t listen to any more. He didn"t know whether Snook.u.ms knew what he was talking about or not, but he did know that the thing the robot had mentioned would have had just such an effect.

Mike strode rapidly across the room and flipped up the shield housing the a.s.sembly Snook.u.ms had mentioned. The lead was definitely askew.

Mike the Angel snapped orders, and the power crewmen descended on the scene of the trouble.

Snook.u.ms went right on delivering his interpretation of the data, but everyone ignored him while they worked. Being ignored didn"t bother Snook.u.ms in the least.

"... and that, in turn, is making the feeder valve field oscillate," he finished up, nearly five minutes later.

Mike was glad that Snook.u.ms had pinpointed the trouble first and then had gone on to show why the defect was causing the observed result. He could just as easily have started with the offending oscillation and reached the bit about the faulty lead at the end of his speech, except that he had been built to do it the other way around. Snook.u.ms made the deduction in his superfast mind and then reeled it off backward, as it were, going from conclusion to premises.

Otherwise, he might have been too late.

The repair didn"t take long, once Snook.u.ms had found just what needed repairing. When the job was over, Mike the Angel wiped his hands on a rag and stood up.

"Thanks, Snook.u.ms," he said honestly. "You"ve been a great help."

Snook.u.ms said: "I am smiling. Because I am pleased."

There was no way for him to smile with a steel face, but Mike got the idea.

Mike turned to the Chief Powerman"s Mate. "Okay, Multhaus, shut it off.

She"s steady now."

Multhaus just sat there, surrounded by a wall of concentration, his hands still on the verniers, his eyes still on the screen. He didn"t move.

Mike flipped off the switch. "Come on, Multhaus, snap to. We"ve still got that beat note to worry about."

Multhaus blinked dizzily as the green line vanished from his sight. He jerked his hands off the verniers, and then smiled sheepishly. He had been sitting there waiting for that green line to move a full minute after the input signal had ceased.

"Happy hypnosis," said Mike. "Let"s get back to finding out which of those tubes in the hull is giving the external field the w.i.l.l.i.e.s."

Snook.u.ms, who had been listening carefully, rolled up and said, "Generator tubes three, four, and thirteen. Three is out of phase by--"

"You can tell us later, Snook.u.ms," Mike interrupted rapidly. "Right now, we"ll get to work on those tubes. You were right once; I hope you"re right again."

Again the power crew swung into action.

Within five minutes Mike and Multhaus were making the proper adjustments on the external field circuits to adjust for the wobbling of the output.

The throb wavered. It wobbled around, going up to two-point-seven cycles and dropping back to one-point-four, then climbing again. All the time, it was dropping in magnitude, until finally it could no longer be felt.

Finally, it dropped suddenly to a low of point-oh-five cycles, hovered there for a moment, then vanished altogether.