old columns. Some carried
ready-loaded cages waiting to be snatched up by hoists. Crane grips came
down, and snapped fast on the cages, and lifted them up and up and out
of sight. There was a Diesel running somewhere, and a man stood and
stared skyward and made motions with his hands, and the Diesel adjusted
its running to his signals. Then some empty cages came down and landed
in a waiting truck body with loud clanking noises. Somebody cast off the
hooks, and the truck grumbled and drove away.

Sally spoke to a preoccupied man in shirt sleeves with a badge on an arm
band near his shoulder. He looked carefully at the passes she carried,
using a flashlight to make sure. Then he led them to a shaft up which a
hoist ran. It was very noisy here. A rivet gun banged away overhead, and
the plates of the Platform rang with the sound, and the echoes
screeched, and to Joe the bedlam was infinitely good to hear. The man
with the arm band shouted into a telephone transmitter, and a hoist cage
came down. Joe and Sally stepped on it. Joe took a firm grip on her
shoulder, and the hoist shot upward.

The hugeness of the Shed and the Platform grew even more apparent as the
hoist accelerated toward the roof. The flooring seemed to expand.
Spidery scaffold beams dropped past them. There were things being built
over by the sidewall. Joe saw a crawling in-plant tow truck moving past
those enigmatic objects. It was a tiny truck, no more than four feet
high and with twelve-inch wheels. It dragged behind it flat plates of
metal with upturned forward edges. They slid over the floor like
sledges. Cryptic loads were carried on those plates, and the tow truck
stopped by a mass of steel piping being put together, and began to
unload the plates.

Then the hoist slowed abruptly and Sally winced a little. The hoist
stopped.

Here--two hundred feet up--a welding crew worked on the skin of the
Platform itself. The plating curved in and there was a wide flat space
parallel to the ground. There was also a great gaping hole beyond.
Though girders rose roofward even yet, this was as high as the plating
had gone. That opening--Joe guessed--would ultimately be the door of an
air lock, and this flat surface was designed for a tender rocket to
anchor to by magnets. When a rocket came up from Earth with supplies or
reliefs for the Platform's crew, or with fuel to be stored for an
exploring ship's later use, it would anchor here and then inch toward
that doo