lan to surround the city with our towers; even those on the
further side would be within range of our power house; and with the city
thus beleaguered, we would attack the wall from every side at once.

We tested now this barrage Tarrano had thrown up. Sprays of its
insulated area came down to protect the wall in front; and protected
also the triangular spaces between the sources of the main beams.
Tentatively one of our towers approached within range; but our rays only
beat into the barrage with the hiss of molten metal plunged into water,
and with a burst of interference sparks. Even at a horizontal thousand
feet we could do nothing. Then we tried altitude. Our projectors,
mounted individually on small platforms automatically controlled to fly
without human pilot, went up and we strove to get them over the barrage.

At five thousand feet one went over safely. But the electronic bomb it
dropped into the city was an easy mark for Tarrano's watchful defense
rays. He exploded it harmlessly when it was still high above him.

After the next time of sleep we invested the city. Our towers were set
in a ring about it, two thousand feet from the wall. They were mobile
units, ready to sail forward or back or upward at any moment. Georg
stayed in command of the instrument room. It was never placed, but
sailed continuously in slow circular flight around the city above our
line. The power house remained in its place, with our largest projector
mounted on the cliff beside it in order to frustrate any further
attacks.

They were solemn moments as we broke our encampment. The girls, far more
agile in the air than men, were lightly dressed, with the supporting
mechanism strapped to them. The heating units enveloped them in an
invisible cloak of warm air. To their left arms a strapped cylinder gave
off a fan-shape area of insulation--an almost invisible shield of
protective barrage some five feet long. It showed as a faint glow of
light; and in flight their left arms could swing it like a shield to
protect their bodies. They had telephonic ear-pieces available; a tiny
mirror fastened to their chests to face them, upon which Georg or
Geno-Rhaalton could project images; a mouthpiece for talking to Georg;
and a belt of offensive weapons, useful within a range of five hundred
feet but no further.

Very alert and agile, twisting and turning in the air were these girls.
We men were similarly equipped, but our movements in the air were
hea