"You are ready to do as I command?" he demanded.

"Yes," whispered Dex. "Yes."

In the beautiful Greca's eyes, as she translated his assent, was
horror. But then, faintly, her mind caught the thought that lay
beneath the Earthman's apparent surrender. She veiled her own eyes
with long lashes, lest they betray the captive's plan to the alert
Rogan. Her lips moved silently; perhaps she was praying to her Great
White One.

* * * * *

"Release him," the Rogan ordered, triumph in his bird-like, shrill
voice. The metal hoops were unfastened. Dex stretched his outraged
body, wincing with the pain of movement; then felt life and strength
returning to him.

"Come with us to the motor," commanded the Rogan, his dull eyes
glinting in anticipation of learning the coveted secret that should
add one more planet to the Rogan's tyranny.

Dex walked to the dismantled atomic engine with him. He walked slowly,
pretending more stiffness and weakness than he really owned to. No use
in letting his captors know that his resilient muscles were so quickly
throwing off the torment of the rack.

As he walked he kept his gaze covertly on that shock-tube that dangled
in the leader's grasp. The rest of the guard had none; they had laid
their weapons down on a far bench on their entrance to the chamber,
depending on the one with which their leader was armed.

Eagerly the Rogans crowded around Dex and the motor that had thus far
baffled them. They bent down from their twelve-foot heights to bring
their staring goggle-eyes closer to the lesson in atomic motive power,
till Dex was in a sort of small dome of Rogans, with their long,
pipe-like legs forming the wall around him, and their thin torsos
inclining forward to make a curved ceiling over him.

The Rogan leader drew Greca within the circle to interpret the
Earthman's explanations.

Dex moved a trifle, to bring himself nearer the tall leader. Again he
glanced covertly at the shock-tube.

"The first thing to tell about our motor," said Dex, stalling for
time, "is that it utilizes the breaking up of the atom as its source
of power."

* * * * *

He edged closer to the Rogan leader.

"You see those electrodes?" he said, pointing to two copper castings
in a chamber between the fuel tank and the small but enormously
powerful turbine that whirled with the released atomic energy. The
Rogan leader blinked assent. His small, ho