do,
it's either wine or a _very_ diluted highball. Right now, this coffee
will do me more good."

Mike heard footsteps coming down the companionway. He glanced out
through the door, which he had deliberately left open. Ensign Vaneski
walked by, glanced in, grinned, and went on his way. The kid had good
sense, Mike thought. He hoped any other passers-by would stay out while
he talked to Leda.

"Does a thing like that happen often?" the girl asked. "Not the fast
solution; I mean the beat note."

"No," said Mike the Angel. "Once the system is stabilized, the tubes
tend to keep each other in line. But because of that very tendency, an
offbeat tube won't show itself for a while. The system tries to keep the
bad ones in phase in spite of themselves. But eventually one of them
sort of rebels, and that frees any of the others that are offbeat, so
the bad ones all show at once and we can spot them. When we get all the
bad ones adjusted, the system remains stable for the operating life of
the system."

"And that's the purpose of a shakedown cruise?"

"One of the reasons," agreed Mike. "If the tubes are going to act up,
they'll do it in the first five hundred operating hours--except in
unusual cases. That's one of the things that bothered me about the way
this crate was hashed together."

Her blue eyes widened. "I thought this was a well-built ship."

"Oh, it is, it is--all things considered. It isn't dangerous, if that's
what you're worried about. But it sure as the devil is expensively
wasteful."

She nodded and sipped at her coffee. "I know that. But I don't see any
other way it could have been done."

"Neither do I, right off the bat," Mike admitted. He took a good swallow
of the hot liquid in his cup and said: "I wanted to ask you two
questions. First, what was it that Snookums was doing just before he
came into the Power Section? Black Bart said he'd been galloping all
over the ship, with you at his heels."

Her infectious smile came back. "He was playing seismograph. He was
simply checking the intensity of the vibrations at different points in
the ship. That gave him part of the data he needed to tell you which of
the tubes were acting up."

"I'm beginning to think," said Mike, "that we'll have to start building
a big brain aboard every ship--that is, if we can learn enough about
such monsters from Snookums."

"What was the other question?" Leda asked.

"Oh.... Well, I was wondering just why you are conne