wall! I was on him, my hand clutching for
his tube. But there was no need. He was out--dead to the world. So
sudden, so unexpected was my mad attack that even he had not had time
to meet it.

I worked fast. In a minute I was in Rubinoff's uniform and had assumed
his face. I was a little taller; no matter. But the finger--that
would be noticed immediately. There was only one thing to do. I stuck
my little finger through one of the holes he had made in the wall and
twisted. Crack! Beads of agony stood out on my forehead, but the break
was just right. By bending the other fingers slightly I could hold
that one in just the position of his.

I picked up the ray-tube with my left hand. If I went out through the
guard-house entrance I might meet other officers and be engaged in
conversation. That might lead to discovery. My cell was on the side of
the prison away from the road; I had noticed no buildings behind it:
I'd chance it. Luck had been with me so far.

* * * * *

I carved out a hole in the wall pierced by the air-hole. It was like
cutting through butter with a red hot knife. I stepped out.

There was no one about. I walked carelessly around the corner of the
building, my hand, holding the tube, buried deep in my pocket. Not far
away was the spherical structure I had spotted as the control room. I
returned salutes. No one stopped to talk to me. Would the guard before
that building require a pass-word?

I heard a shout behind me. My escape was discovered! At once I broke
into a run and dashed past the guard, shouting: "Prisoner escaped!
Came this way!" The man gaped. The shouting behind me grew louder. I
heard the thud of many feet, running. I flung open the door, slammed
it shut behind me, and turned the key.

A long row of giant electrode bulbs, as tall as a man, stretched
before me--the source of the Zeta-ray. From here came the power that
held back the waters, that bored the tunnel. A thunderous knocking
shook the door. Someone at a huge switchboard turned toward me.
Instantly my hand was out of my pocket, and the ray-tube leveled at
the nearest bulb. I pressed the trigger. The bulb crashed. I swept
down the line. Crash, crash, crash--they were all gone.

I whirled to meet the expected attack. It was wholly instinctive, for
in a second we'd all be dead anyway. The waters would be down on us.

But the switchboard operator wasn't springing at me. Instead, he was
tugging frantic