against
the elongated shield of Andromeda. They soared out of the picture,
appeared again minutes later, zooming in from the other direction in
two flights of four ships and three.

"Come on!" Sophia cried over her shoulder, irising the door and
plunging from the room. Temple followed at her heels but her Jupiter
trained muscles pushed her lithe legs in long, powerful strides and
soon she outdistanced him. By the time he reached the armaments vault,
breathless, she was seated at the single gun-emplacement, her fingers
on the controls.

"Watch the viewing screen and tell me how we're doing," Sophia told
him, not taking her eyes from the dials and levers.

Temple watched, fascinated, saw a thin pencil of radiant energy leap
out into space, missing one of the ships by what looked like a scant
few miles. He called the corrective azimuth to her, hardly surprised
by the way his mind had absorbed and now could use its new-found
knowledge.

Temple understood and yet did not understand. For example, he knew the
station had but one gun and Sophia sat at it now, yet in certain ways
it didn't make sense. Could it cover all sectors of space? His mind
supplied the answer although he had not been aware of the knowledge an
instant before: yes. The space station did not merely rotate. Its
surface was a spherical projection of a moving Moebius strip and
although he tried to envision the concept, he failed. The weapon could
be fired at any given point in space at twenty second intervals,
covering every other conceivable point in the ensuing time.

Sophia was firing again and Temple watched the thin beam leap across
space. "Hit!" he roared. "Hit!"

Something flashed at the front end of the lead ship. The light blinded
him, but when he could see again only six ships remained in
space--casting perfect shadows on the Andromeda Galaxy! The source of
light, Temple realized triumphantly, was out of range, but he could
picture it--a glowing derelict of a ship, spewing heat, light and
radioactivity into the void.

"One down," Sophia called. "Six to go. I like your American
expressions. Like sitting ducks--"

She did not finish. Abruptly, light flared all around them. Something
shrieked in Temple's ears. The vault shuddered, shook. Girders
clattered to the floor, stove it in, revealing black rock. Sophia was
thrown back from the single gun, crashing against the wall, flipping
in air and landing on her stomach.

Temple ran to her, turn