he wanted
nothing but to drive on up to the end of the shaft, come out into that
world wherever the shaft ended, then try to fight his way through to
the great hall where he hoped to find Phee-e-al. And his haste made
him overestimate the passing time; their journey had been swifter than
he knew.

"I may have passed it," Loah was saying doubtfully. "I may have come
too far." Then she interrupted herself and sprang to the controls.

They drifted slowly back. "It is different now," Loah said; "the air
rises more swiftly than before." She stared from the windows while she
drove the _jana_ slowly up and down, trying to bring it to equilibrium
in the strong up-draft.

The air entered the shell through a little opening with the same
pungent tang Rawson had noticed before. He had wondered about the air.
Down near the neutral zone it was dense, yet he had not minded the
pressure too greatly--and that had been puzzling.

"Rock pressure and air pressure," he had reasoned; "they are two
different things. If the rock flowed, any air that it trapped would be
squeezed to a liquid. But it doesn't flow--that red stuff is solid; so
the air pressure is only the weight of the air column itself. But even
that should be enormous."

He could only conclude that the lessened pressure came from that
strange counter-gravitation, the repelling force from the center of
the earth. Perhaps it tended to dissipate the molecules, held them
farther apart, prevented their squeezing in together, and battering
with a thousand little impacts on a point where one had hit before.

Their _jana_ swayed gently as if the smooth air currents were
disturbed and were drifting them sideways; and then, at last, Loah,
peering from a window, sprang back and moved a lever. Beneath them was
the softly-cushioned thud of the shell seating itself on firm rock.

* * * * *

They were in another of the interminable caves, Rawson found when he
opened the door. The _jana_ was resting a few feet in from the edge of
the shaft. Cautiously they got out, but even without their weight it
had a slight negative buoyancy.

"Oro is pulling more strongly than Grah," Dean said, and smiled.
Already the names seemed familiar to him.

The two lifted the _jana_ and carried it back some twenty feet more
before Rawson realized how unnecessary this was.

"We'll never be using it again," he said. "If I've guessed right it
will stay here as long as the ro