awson felt the same current sweeping and
whirling gustily about him.

Now his companions were across the room, and between him and them in
the center of the floor he saw the mouth of a black well, a pit some
twenty or more feet across. Directly above, where the red rock stuff
formed a domed ceiling, he found a counterpart of the pit
below--another great bore or open shaft, roughly circular. Apparently
it went straight on up and was a continuation of that lower pit.

"This room was cut out," Rawson was thinking, "by the white people or
the mole-men--Lord knows who, or when, or why. Cut out around this big
shaft...."

His thoughts trailed off. Even thinking seemed impossible under the
battering of the roaring noise that pounded about him. Then another
thought pierced through the bedlam. He had found the source of the
uproar.

* * * * *

That upper shaft, the hole that went on up, must be plugged. There was
no outlet that way, and this air that drove endlessly upward from the
room must be coming from the lower shaft. It was striking up into that
upper cavity.

An organ pipe, truly. But whence came the unending blast of air to
keep that gigantic instrument in operation? Rawson dropped to his
knees and crept slowly across the floor toward the pit. He must test
his theory--see if that was where the air was driving in.

Just short of the brink he stopped. The girl had called--a cry of
alarm. She was running swiftly toward him, circling the pit. And
Rawson, as she tugged at him, trying to draw him back, knew that she
had mistaken his motive. She had thought he was going to cast himself
down.

He did not need to go farther. He was close to the edge. And now, even
above that roaring sound he heard the rush of the column of air. He
seated himself on the stone floor and smiled up at the girl
reassuringly. Her eyes that had been dark with fear changed swiftly to
a look so sweetly, beautifully tender that Dean Rawson found himself
thrilled and shaken by an emotion that set his nerves to quivering
even more than did the sonorous vibration from above.

Her companions had joined her. Dean saw her eyes regarding them
steadily. Then, as if reaching some sudden final conclusion in her
own mind, she dropped swiftly to her knees beside him, raised one of
his hands in hers and pressed her soft lips against it.

And Dean, even had he known their language, could not in that moment
have spoken. There