le the Mother's busy at the front. I'll see you get transportation up
there." Turning toward the door, she glanced sidelong at Dworn....
"You'll have to go separately, since a spider will only carry two. I'm
leaving right away myself; _you_ may come with me in my machine--"

"No, he won't," declared Qanya with finality, tightening her hold on
Dworn's arm. "He can ride with old Zimka."

Purri stalked through the doorway before them, grumbling to herself,
"Why is it the best ones always get away?"

* * * * *

Earlier in the night, climbing spiders--the only machines which could
manage the ascent of the toppled Barrier--had scouted the periphery of
the drones' fortress, and discovered the sole possible approach to it.
At a single spot above the slide, a low ridge made it feasible to
surmount the rim and steal out onto the table-land beyond without coming
in direct view of the enemy's installations.

Once that was known, the council of chiefs decided on a daring strategy.
Up the thousand-foot slope of tumbled rocks below that one vulnerable
point, a fantastic supply line was established. One by one, machines
from among those massing on the desert below toiled upward until wheels
or treads could carry them no further; then they were hoisted bodily
over the precipices by the invaluable spiders, who anchored themselves
firmly in place with the powerful steel cables they ordinarily used for
snaring prey, and used other such cables as pulleys.

Through the remaining hours of darkness the joined forces labored with
Herculean devotion to accomplish the seemingly impossible task. There
were brushes with the enemy, for the wingless drones still came and went
about the mountainside and from time to time their winged kindred flew
overhead. But strict orders had gone out to all the allied
peoples--avoid opening fire, avoid precipitating a general engagement,
and freeze motionless whenever the fliers passed over. This last
instruction rested on the observation that the robot predators, with
whatever sensory devices they used, apparently had difficulty in
spotting anything but a moving target.

In this wise, when dawn began to break, close to three hundred
first-line fighting machines of a dozen different species had been
raised to the summit of the Barrier. Thence they filtered cautiously out
across the plateau, in a great arc moving to enclose the hollow of the
drones.

* * *