l--watch it, Doyle--WATCH
IT!"

"Kinnison, take it!" Fire Control barked, voice now neither low nor
steady, and without waiting to see whether Doyle would hit or miss.
"It's in Zone Three already--collision course!"

"Harper! Take over!"

Kinnison got the data, solved the equations, launched five torpedoes at
fifty gravities of acceleration. One ... two--three-four-five; the last
three as close together as they could fly without setting off their
proximity fuzes.

Communications and mathematics and the electronic brains of calculating
machines had done all that they could do; the rest was up to human
skill, to the perfection of co-ordination and the speed of reaction of
human mind, nerve, and muscle.

Kinnison's glance darted from plate to panel to computer-tape to meter
to galvanometer and back to plate; his left hand moved in tiny arcs the
knobs whose rotation varied the intensities of two mutually
perpendicular components of his torpedoes' drives. He listened
attentively to the reports of triangulating observers, now giving him
data covering his own missiles, as well as the target object. The
fingers of his right hand punched almost constantly the keys of his
computer; he corrected almost constantly his torpedoes' course.

"Up a hair," he decided. "Left about a point."

The target moved away from its predicted path.

Down two--left three--down a hair--_Right_! The thing was almost through
Zone Two; was blasting into Zone One.

He thought for a second that his first torp was going to connect. It
almost did--only a last-instant, full-powered side thrust enabled the
target to evade it. Two numbers flashed white upon his plate; his actual
error, exact to the foot of distance and to the degree on the clock,
measured and transmitted back to his board by instruments in his
torpedo.

Working with instantaneous and exact data, and because the enemy had so
little time in which to act, Kinnison's second projectile made a very
near miss indeed. His third was a graze; so close that its proximity
fuze functioned, detonating the cyclonite-packed war-head. Kinnison knew
that his third went off, because the error-figures vanished, almost in
the instant of their coming into being, as its detecting and
transmitting instruments were destroyed. That one detonation might have
been enough; but Kinnison had had one glimpse of his error--how small it
was!--and had a fraction of a second of time. Hence Four and Five
slammed home