earing out through the opposite wall, was an identical
beam.

"The terminals for the metal plate system that extends over the whole
red spot," murmured Brand. "This building _is_ important. But what can
I do to throw sand in the gears before I'm caught and killed...?"

He surveyed the great round room below him more thoroughly. Now he
saw, right in the center of the huge control board, a solitary lever,
that seemed a sort of parent to all the other levers and switches. It
was flanked by a perfect army of gauges and indicators; and was
covered by a glass bell which was securely bolted to the rock slab.

"That looks interesting," Brand told himself. "I'd like to see that
closer, if I can climb down from here without being observed....
Why"--he broke off--"where is everybody!"

For the first time, in the excitement and concentration of his
purpose, the emptiness of the place struck him. There was no sign of
light in the great building--no workmen or slaves anywhere. There was
just the great coils, with the streamers of blue light bridging them
and emitting the high-pitched, monotonous hum audible outside the
dome, and the complicated control board with its quivering indicator
needles and mysterious levers. That was all.

"Must be out to lunch," muttered Brand, his eyes going fascinatedly
toward that solitary, parent lever under its glass bell. "Well, it
gives me a chance to try some experiments, anyway."

* * * * *

It was about fifty feet from his perch to the floor; but a few feet to
one side was a metal beam that extended up to help support the trussed
weight of the roof. He jumped for this, and quickly slid down it.

He started on a run for the control board; but almost immediately he
stopped warily to listen: it seemed to him that he had caught,
faintly, the squeaking, high tones of Rogan conversation.

Miraculously, the sound seemed to come from a blank wall to his left.
He crept forward to investigate....

The mystery was solved before he had gone very far. There was an
opening in the wall leading off to an annex of some kind outside the
dome building. The opening was concealed by a set-back, so that at
first glance it had seemed part of the wall itself. From this opening
drifted the chatter of Rogans.

Brand stole closer, finally venturing to peer into the room beyond
from an angle where he himself could not be seen. And he found that
his whimsical reference to "lunch" ha