orld somewhere that was
inhabited by compatible human beings of Grade Two. He could learn
nothing about the faster-than-light drive.

Number Ten was another queer--the Tellurians were found incompatible.

"Let's go down anyway." Belle suggested. "Overcome this unwillingness of
ours and find out. What do you think they've got down there, Clee
Garlock, that could possibly handle you and me both?"

"I don't think it's a case of 'handling' at all. I don't know what it
is, but I believe it's fatal. We won't go down."

"But it doesn't make sense!" Belle protested.

"Not yet, no; but it's a datum. Enough data and we'll be able to
formulate a theory."

* * *

"You and your theories! I wish we could get some _facts_!"

"You can call that a fact. But I want you and Jim to do some
math. We know that we're making mighty long jumps. Assuming that they're
at perfect random, and of approximately the same length, the probability
is greater than one-half that we're getting farther and farther away
from Tellus. Is there a jump number, N, at which the probability is
one-half that we land nearer Tellus instead of farther away? My
jump-at-conclusions guess is that there isn't. That the first jump set
up a bias."

"Ouch. _That_ isn't in any of the books," James said. "In other words,
do we or do we not attain a maximum? You're making some bum assumptions;
among others that space isn't curved and that the dimensions of the
universe are very large compared to the length of our jumps. I'll see if
I can put it into shape to feed to Compy. You've always held that these
generators work at random--the rest of those assumptions are based on
your theory?"

"Check. I'm not getting anywhere studying my alleged Xenology, so I'm
going to work full time on designing a generator that will steer."

"You tried to before. So did everybody else."

"I know it, but I've got a lot more data now. And I'm not promising,
just trying. Okay? Worth a try?"

"Sure--I'm in favor of anything that has any chance at all of working."

Jumping went on; and Garlock, instead of going abroad on the planets,
stayed in the _Pleiades_ and worked.

* * *

At Number Forty-three, their reception was of a new kind. They were
compatible with the people of this world, but the Inspector advised them
against landing.

"I do not forbid you," he explained, carefully. "Our humans are about to
destroy themselves with