dling; the soil changing to rocky barrenness at the
border of the Cold Country. And then the snow-plains, the mute frozen
rivers of ice, the mountains.

In the twilight of the Cold Country autumn, we sailed up to the
mountains and approached to the City of Ice. Alert, all of us now, as at
an altitude of a few thousand feet we circled about, marking time until
the power plant had selected its base and landed to make ready for the
battle.

Throughout the trip we had expected--had anticipated the possibility--of
a surprise attack by Tarrano; an ambush in the open air, perhaps
by some means strange to us. But the vision magnifiers, the
microphones--encompassing every known range of sight and sound--showed
us nothing. Especially at the mountains we had thought to meet
opposition. But at first none came. It seemed somehow ominous, this lack
of action from Tarrano; and when the leader of our line--a tower
vehicle--rose sharply to scale the jagged peaks of the Divide, the flare
of a hostile electronic bomb rising came almost as a relief. From the
instrument room--forewarned an instant by the hiss of our microphones--I
saw the bomb start upward. Slowly as a rocket it mounted--a blurred ball
of glowing violet light, quite plain in the dim twilight. I knew that
the tower platform at which it was directed would have time to throw out
its insulation; I knew that the insulation would doubtless be
effective--yet my heart leaped nevertheless. At my hand was a projector;
but in those few seconds the tower just in advance of us in the line was
quicker. Its ray darted at the violet ball; the soundless explosion
threw a wave of sparks about the menaced tower, like a puff--a pricked
bubble of soap-film--the violet ball was dissipated. But I saw the
menaced tower rock a trifle from the shock.

Geno-Rhaalton's face in the mirror beside me was very solemn. I heard
him murmuring something to the other towers, saw their light flash
downward, searching the mountain defiles. And as I watched that little
image of Rhaalton, I chanced to notice a mirror on Rhaalton's desk.
Rhaalton himself was looking at it--a mirror which had been dark, but
which now flashed on. An outlaw circuit! The mirror imaged the face of
Tarrano. Tarrano grinning ironically!

CHAPTER XXXIV

_Invisible Assailants_

We did not locate the source of the bomb, and no others rose to assail
us. The mountain defiles, so far as our lights could illuminate them,
seemed d