he profession and
who was possessed of instantaneous nervous reaction and of the highest
degree of manual dexterity and control. Under his right and left hands
were the double-series potentiometers actuating the variable-speed
drives of the flight-angle directors in the hour and declination ranges;
before his eyes was the finely marked micrometer screen upon which the
guiding goniometer threw its needle-point of light; powerful optical
systems of prisms and lenses revealed to his sight the director-angles,
down to fractional seconds of arc. It was the task of the chief pilot
to hold the screened image of the cross-hairs of the two directors in
such position relative to the ever-moving point of light as to hold the
mighty vessel precisely upon its course, in spite of the complex system
of forces acting upon it.

For almost an hour Breckenridge sat motionless, his eyes flashing from
micrometer screen to signal panel, his sensitive fingers moving the
potentiometers through minute arcs because of what he saw upon the
screen and in instantaneous response to the flashing, multi-colored
lights and tinkling signals of his board. Finally, far from earth, the
moon's attraction and other perturbing forces comparatively slight, the
signals no longer sounded and the point of light ceased its irregular
motion, becoming almost stationary. The chief pilot brought both
cross-hairs directly upon the brilliant point, which for some time they
had been approaching more and more nearly, adjusted the photo-cells
and amplifiers which would hold them immovably upon it, and at the
calculated second of time, cut out the starting power by means of
another set of automatically timed relays. When only the regular driving
power was left, and the acceleration had been checked and found to be
exactly the designated value of 981.286 centimeters, he stood up and
heaved a profound sigh of relief.

"Well, Steve, that's over with--we're on our way. I'm always glad when
this part of it is done."

"It's a ticklish job, no fooling--even for an expert," the mathematician
agreed. "No wonder the astronomers think you birds are the ones who are
gumming up their dope. Well, it's about time to plug in on E2. Here's
where the fireworks start!" He closed the connections which transferred
the central portion of the upper lookout screen to a small micrometer
screen at Breckenridge's desk and plugged it into the first
check-station. Instantly a point of red light, sur