of the gas apparatus.

"Pressure, fifty-two centimeters--more than I dared hope for--and
analysis all x, I believe. Oxygen concentration a little high, but
not much."

"We won't have to wear the space-suits, then?"

"Not unless I missed something in the analysis. The pressure corresponds
to our own at a height of about three thousand meters, which we can get
used to without too much trouble. Good thing, too. I brought along all
the air I could get hold of, but as I told you back there, if we had to
depend on it altogether, we might be out of luck. I'm going to pump some
of our air back into a cylinder to equalize our pressure--don't want
to waste any of it until we're sure the outside air suits us without
treatment."

* * * * *

When the pressure inside had been gradually reduced to that outside and
they had become accustomed to breathing the rarefied medium, Stevens
opened the airlock and the outside doors, and for some time cautiously
sniffed the atmosphere of the satellite. He could detect nothing harmful
or unusual in it--it was apparently the same as earthly air--and he
became jubilant.

"All x, Nadia--luck is perched right on our banner. Freedom, air, water,
power, and coal! Now as you suggested, we'll go places and do things!"

"Suppose it's safe?" Her first eagerness to explore their surroundings
had abated noticeably. "You aren't armed, are you?"

"No, and I don't believe that there was a gun of any kind aboard the
_Arcturus_. That kind of thing went out quite a while ago, you know.
We'll take a look, anyway--we've got to find out about that coal before
we decide to settle down here. Remember this half-gravity stuff, and
control your leg-muscles accordingly."

Leaping lightly to the ground, they saw that the severed section of
fifty-inch armor, which was the rim of their conveyance, almost blocked
the entrance to the narrow canyon which they had selected for their
retreat. Upon one side that wall of steel actually touched the almost
perpendicular wall or rock; upon the other side there was left only a
narrow passage. They stepped through it, so that they could see the
waterfall and the gorge, and stopped silent. The sun, now fairly high,
was in no sense the familiar orb of day, but was a pale, insipid thing,
only one-fifth the diameter of the sun to which they were accustomed,
and which could almost be studied with the unshielded eye. From their
feet a grassy meadow a f