ket-tube. The laboratory there at its
base was in confusion indescribable, the workmen running hither and yon
in the effort to escape the terrific heat that radiated from the red
hot breech of the tube. They jammed the exits in their anxiety to be
anywhere but near this monster source of energy whose pulsating roar
drowned out all other sounds in the vast chamber.

Already Antrid was accelerating in velocity. Her vitals were wrenched
and twisted, groaning in protest.

"Quick now!" Blaine was adjusting one of the invisible cloaks for
Ulana. He'd _have_ to take her with him. And a silent prayer for
her safety was on his lips.

Invisible now, and hand in hand, they followed Dantor through the
deserted passageways to the lift which carried them quickly to the
roof. A drumming sound came to their ears as they stood there looking
up into the blackness above the blue-white lights of Antrid. Vibrating
to the tremendous roar of the rocket-tube, the copper shell emitted a
constantly increasing reverberation that was like a long drawn peal of
thunder on Earth or Venus. It was awe-inspiring, that sonorous
bombilation; deafening.

* * * * *

Dantor was fumbling with the mechanisms of the remote control which
Tiedus had used in returning the basket lift to the car that had
brought the two Earth men from Ilen-dar. Again and again he returned to
his manipulations after peering anxiously upward. But the basket did
not respond to the call. They were marooned atop the empty shell of the
Tritu Anu!

"Carson! Ulana! Where are you?" the aged scientist shouted above the
din, his face a tragic mask, his lips compressed with anxiety and
disappointment.

They grasped him to reassure him, each taking a hand. Carson, placing
his lips close to the old man's ear, inquired anxiously, "What's the
trouble?"

"The car does not respond. Something has happened to the motors,
probably on account of the vibration. I can do nothing."

And then, piercingly through the thunderings of the copper shell, a
voice broke in--Ianito's voice. "Dantor!" it shrieked. "At last I have
found you. I need your help immediately. Wait there for the monorail."

Dantor gripped them tightly to enjoin silence. Ianito had located the
scientist with the searching ray and was still watching and listening
at his crystal. He seemed not to know that Blaine and Ulana were there.

"Very well, oh Ianito. I shall wait," Dantor shouted.