“Yes . . . after a fashion . . . yes, I do. . . . Well, anyway, now I know what to tell Ross.”

He called the captain and issued instructions. The Vortex Blaster II darted away at full touring blast.

“Now what?” Cloud asked.

“We practise.”

“Practise what?”

“How should I know? Everything, I guess. Oh, no, the Fives emphasized ‘scope,’ whatever that means. ‘Scope in heights and depths.’ Does that ring any bells?”

“Not loud ones, if any. All it suggests to me is spectra of some kind or other.”

“It could, at that.” Joan caught her lower lip between her teeth. “But before we start playing scales, let’s see if we can deduce anything helpful—examine our points of contact and so on. What have we got to go on?”

“We have one significant point in space. That’s all.”

“Oh no, it isn’t. You’re forgetting one other highly significant fact. The data fitted the growth-of-population curve exactly, remember.”