oom with no windows but a single door. Again he
crept carefully around close to the wall. No, he could not be
mistaken! He paused before the center of the wall opposite the door.
For a moment he stood quite motionless, then he moved a few feet to one
side. Again he returned, only to move a few feet to the other side.

Once more he made the entire circuit of the room, feeling carefully
every foot of the walls. Finally he stopped again before the
particular section that had aroused his curiosity. There was no doubt
of it! A distinct draft of fresh air was blowing into the chamber
through the intersection of the masonry at that particular point--and
nowhere else.

Tarzan tested several pieces of the granite which made up the wall at
this spot, and finally was rewarded by finding one which lifted out
readily. It was about ten inches wide, with a face some three by six
inches showing within the chamber. One by one the ape-man lifted out
similarly shaped stones. The wall at this point was constructed
entirely, it seemed, of these almost perfect slabs. In a short time he
had removed some dozen, when he reached in to test the next layer of
masonry. To his surprise, he felt nothing behind the masonry he had
removed as far as his long arm could reach.

It was a matter of but a few minutes to remove enough of the wall to
permit his body to pass through the aperture. Directly ahead of him he
thought he discerned a faint glow--scarcely more than a less
impenetrable darkness. Cautiously he moved forward on hands and knees,
until at about fifteen feet, or the average thickness of the foundation
walls, the floor ended abruptly in a sudden drop. As far out as he
could reach he felt nothing, nor could he find the bottom of the black
abyss that yawned before him, though, clinging to the edge of the
floor, he lowered his body into the darkness to its full length.

Finally it occurred to him to look up, and there above him he saw
through a round opening a tiny circular patch of starry sky. Feeling
up along the sides of the shaft as far as he could reach, the ape-man
discovered that so much of the wall as he could feel converged toward
the center of the shaft as it rose. This fact precluded possibility of
escape in that direction.

As he sat speculating on the nature and uses of this strange passage
and its terminal shaft, the moon topped the opening above, letting a
flood of soft, silvery light into the shadowy place.