away are we?"

"I put on full acceleration fifteen hours ago, when we passed Neptune,
and we have covered thirty billion miles--three hundred times as far as
from the moon to the sun, but only one half of one per cent of a
light-year."

I was speechless, and Garth led me back to the control board. He pointed
out the acceleration control, now turned up to its last notch forward;
he also showed me the dials which were used to change our direction.

"Just keep that star on the cross hairs. It's Pi Orionis, a little out
of our course, but a good target since it is only twenty-five
light-years away. Half the light is deflected on this screen, with a
delicate photo-electric cell at its center. The instant the light of the
star slips off it, a relay is started which lights a red lamp here, and
in a minute sounds a warning bell. That indicator over there shows our
approach to any body. It works by the interaction of the object's
gravitational field with that of my projector, and we can spot anything
sizable an hour away. Sure you've got everything?"

* * * * *

It all seemed clear. Then I noticed at the top three clock-like dials;
one to read days, another to record the speeds of light, and the third
to mark light-years traveled.

"These can't really work?" I said. "We have no way to check our speed
with outer space."

"Not directly. This is geared with clockwork to represent an estimate
based on the acceleration. If your theory is right, then the dials are
all wrong."

"And how long do you expect to go ahead without knowing the truth?"

"Until we ought to be at Pi Orionis. At two weeks and twenty-five
light-years by the dials, if we aren't there we'll start back. By your
figuring, we shouldn't be yet one light-year on the way. Anything more?"

"No, I think I can manage it."

"Wake me if anything's wrong. And look out for dark stars." Then he had
left me there at the controls. In five minutes he was asleep and the
whole ship was in my hands.

* * * * *

For hours nothing happened. Without any control of mine, the ship went
straight ahead. I could get up and walk about, with a weather eye on the
board, and never was there the flash of a danger light. But I was unable
to feel confident, and went back to look out through the glass.

The stars were incredibly bright and clear. Right ahead were Betelguese
and Rigel, and the great nebula of Orion still bey