what was the purpose of this well? Was it a trap
to entice a prisoner into an unwary climb and then let gravity drag him
over? The whole setup was meaningless. Perhaps meaningless only to him,
Shann conceded, with a flash of level thinking. The situation could be
quite different as far as the natives were concerned. This structure did
have a reason, or it would never have been erected in the first place.

"What's the matter?" Thorvald's voice was rough with impatience.

"This thing's a well." Shann edged about a fraction to call back. "The
inside is open and--as far as I can tell--goes clear to the planet's
core."

"Ladder on the inside too?"

Shann squirmed. That was, of course, a very obvious supposition. He kept
a tight hold with his left hand, and with the other, he did some
exploring. Yes, here was a hollow right enough, twin to those on the
outside. But to swing over that narrow edge of safety and begin a
descent into the black of the well was far harder than any action he had
taken since the morning the Throgs had raided the camp. The green mist
could hold no terrors greater than those with which his imagination
peopled the depths now waiting to engulf him. But Shann swung over,
fitted his boot into the first hollow, and started down.

The only encouragement he gained during that nightmare ordeal was that
those holes were regularly spaced. But somehow his confidence did not
feed on that fact. There always remained the nagging fear that when he
searched for the next it would not be there and he would cling to his
perch lacking the needful strength in aching arms and legs to reclimb
the inside ladder.

He was fast losing that sense of well being which had been his during
his travels through the fog; a fatigue tugged at his arms and weighed
leaden on his shoulders. Mechanically he prospected for the next hold,
and then the next. Above, the oblong of half-light grew smaller and
smaller, sometimes half blotted out by the movements of Thorvald's body
as the other followed him down that interior way.

How far _was_ down? Shann giggled lightheadedly at the humor of that, or
what seemed to be humor at the moment. He was certain that they were now
below the level of the sand floor outside the slab. And yet no end had
come to the well hollow.

No break of light down here; he might have been sightless. But just as
the blind develop an extra perceptive sense of unseen obstacles, so did
Shann now find that he was awa