f he caught up with
us. He had his spear and we were without ours.

The steep terminus of the great Northern Glacier hove into view. Far
below was the broad fertile habitable belt, stretching as far as the
eye could see. A lump rose in my throat as I ran. It was our earth,
our heritage down there--and here we were, fleeing for our lives,
dispossessed by bits of metal and quartz, machines that we had
fashioned.

Hovering in the air, on a level with us, were scout planes, vigilant
guardians of the frontier.

Once a prolat had become crazed by the eternal ice and cold, and had
ventured down the side of the Glacier, to reach the warm lands his
thin blood hungered for. As soon as he had painfully clambered to the
bottom, within the area of the televisors, a plane had swooped and
crushed him, while we, lining the edge, had witnessed the horror
helplessly.

Yet Keston ran on confidently. Abud was just a little way behind,
bellowing exultantly, when we came to the jumping-off place. He was
sure he had us now.

Keston slid from view. It was sheer suicide to go down there, I knew;
yet, to remain where I was, meant certain death. Abud's spear was
already poised to thrust. There was only one thing to do, and I did
it. I threw myself over the rim, just where Keston had disappeared.

* * * * *

I landed with a thud on a narrow ledge of ice. The surface was glassy
smooth, and I started slipping straight toward the outer edge, a sheer
drop of a thousand feet to the valley below. I strove to recover my
balance, but only accelerated my progress. Another moment and I would
have plunged into the abyss, but a hand reached out and grabbed me
just in time. It was Keston.

"Hold tight and follow me," he whispered urgently, "we've no time to
lose. The master machine is seeing us now in the visor screen, and
will act."

I had an impulse to turn back, but Abud's face was leering down at us.

"I'll get you for this!" he screamed, and let himself down heavily
over the ledge.

Keston edged his way along the treacherous trail, I after him. It was
ticklish work. A misstep, and there would be nothing to break our
fall.

I heard a siren sound, then another; and another. I wasted a precious
moment to look up. A scout plane was diving for us, on a terrific
slant. The air was black with aircraft converging on us. The master
machine had seen us! I sensed utter malevolence in the speed of these
senseless metal