e? Isn't that supposed to cut across warp-lines?
Wouldn't that reduce to zero the strategic importance of our friend,
Candar?"

At this, Manning Reine broke in excitedly, "But that's just the point,
Thane! Remember I mentioned there were certain limits to the
second-stage drive. We can, to a large extent, manufacture our own
lines. But they are never wholly independent of the existing natural
lines through space. Our dependence on the galactic lines varies from
almost zero to almost unitary, depending on our position in space. The
Onzarian Confluence has much the same effect as a whirlpool.
Theoretically, we could force our way out of the whirlpool and go
through the center of the Galaxy by a different route. But the energy
required approaches infinity."

Thane stepped over to the map. He pointed to the Onzarian Confluence.
"O.K. There's our bottleneck. But where's the cork? Just how do you
figure on stopping a fleet if it does surface at the Onzarian
Confluence for two or three microseconds?"

Pyuf slapped the butt of his cigarette across the tray on Reine's
desk. "There, Agent Thane, we reach the point of the whole show. But
let's get the story straight from the source." His eyes went to Reine.

Reine, pouring his second cup of coffee, looked up. "If you mean me,
that's not very accurate. It's true that it was developed in my
laboratory but Astrid was the one who saw the hint, originally, and
did all the development. I'm not even familiar with all the details."
He smiled apologetically to Thane. "We're talking about the Tracer. As
a by-product of our main job we discovered a new way of plotting
warp-lines. Instead of doing it by mathematics we found a way of
plotting warps directly by instrument. Well, I was on the main line of
research, and I had three times as much as I could do already. I just
regarded this as a curiosity. But Astrid took it and built the
Tracer."

Pyuf interrupted. He was not the man, Thane saw, who could abide
technical explanations when they had a clear political implication.
"The Tracer," he said, "is the cork for your bottleneck. With the
tracer, we know when any ship is operating on second-stage drive. With
two tracers, separated on a baseline of a few million kilometers, we
can plot position closely. Three tracers will pin-point them, and for
a trip across the center of the Galaxy, we will know when and where
they'll have to surface."

"That fits all right," Thane said, "but why tie