t
marked Tugh; it must have been a beam signal he was carrying. It moved
slowly, retarded by distance, but it was almost to the gate; and then
it reached there.

"He's gone through!" I called. Then I saw him on the land side. He had
escaped us and joined the Robots. The lights showed them all coming
for the gate.

And then Tina abruptly found the loosened wire.

"I have it!" she exclaimed.

She stood up, tugging with all her strength at the great switch-lever.
I saw, up there on the top of the dam, a surge of sparks as the
current hissed into the wall-barrier; saw the barrier glow a moment
and then subside. And presently the lights of the balked Robots, Tugh
with them, retreated back into the wrecked and blood-stained city.

"We did it!" exclaimed Larry. "We're impregnable here. Tina, now the
air-power, for help may be on its way. And then call some other city.
Can you do that? They must have sent us help by now."

* * * * *

In a moment the air-power went on, and the city lighting system. Then
Tina was at the great transmitter. As she closed the circuits, London
was frantically calling us. In the midst of the chaos of electrical
sounds which now filled the control room, came the audible voice of
the London operator.

"I could not get you because your circuit was broken," it said. "Our
air-vessel _Micrad_; bearing the large projector of the Robot-deranger,
landed on the ocean surface two hundred miles from New York harbor. It
was forced down when your district air-power failed."

Tina said hurriedly, "Our air-power is on now. Is the _Micrad_
coming?"

"Wait. Hold connection. I will call them." And after a moment's pause
the London voice came again: "The _Micrad_ is aloft again, and should
be over New York in thirty minutes. You are safe enough now."

As the voice clicked off Tina's emotion suddenly overcame her. "Safe
enough! And our city red with human blood!"

A wild thought abruptly swept me. Mary Atwood was back there in the
cavern, alone, waiting for me to return! Subconsciously, in the rush
of these tumultuous events, my mind had always been on her; she was
secure enough, no doubt, locked in that room. But now Tugh was back in
the city, and realizing that his cause was lost he would return to
her!

I hastily told Larry and Tina.

"But he cannot open the door to get into her," said Larry.

But Migul could open the door. Where was Migul now? It set me
shuddering.