sparent
shell, and beneath this Ben was strapped.

Through the shell he saw one of the men of Teris brought into the room and
placed in a similar position on another table. Wires were strung between
the two shells and somewhere a machine began to hum. The shells filled with
a white vapor that lingered a moment and then was gone.

Although he had known what was to happen Ben could not control his
amazement. For the man who came out of the other shell was an exact replica
of himself! Within minutes he saw the other dressed in his own flying suit.

"You see how simply we solve the problem?" Arndis asked. "Ben Sessions will
return to Earth and there will be no search. He will report that he found
nothing and request that he be allowed to try again. By that time we shall
be ready to attack."

Ben's arms had been untied, and now he put his hand to his face, as though
to rub some tender spot. The move attracted no undue attention. An instant
later he had two fingers inside his mouth and was working loose the cap
over his tooth.

His next move took them completely by surprise. With a leap he was half way
across the room and lunging for his double. Ben brought the man down with a
flying tackle and for seconds they wrestled on the floor. Then a hairy hand
tore Ben loose and he was hauled to his feet. He had done little harm to
the other.

"Not quite fast enough," Arndis said. "Within minutes he will be aboard the
Rapier and on his way." Her voice rose. "Take this one back to the locks."

* * * * *

"Doesn't it ever get dark here?" Ben asked.

He and Murchison and the others had been allowed to come out of the tube
after what seemed hours of toil. They sat now in a tiny cell into which air
came through slits in the wall.

"No," Murchison said. "But Bannon has a good watch and we're able to keep
track of time. It's exactly six days and three hours since you were put to
work."

Ben nodded thoughtfully. There was not much time left. Work on the locks
went on endlessly, and sooner than he could have believed possible they
were being completed. Given enough slaves, he thought, anything could be
accomplished.

Gluing his eyes to one of the slits, he peered out. The last of the giant
gates was being installed. Their own crew would have only one more shift
before the job was finished.

Beyond the excavation Ben could see the tower from which the locks were
controlled. Bannon, who had been in