," began Dixon. "We've come to sign you up
for the Academy sports program."

They made themselves comfortable in the room.

"You have a chance to take part in three sports. Free-fall wrestling,
mercuryball and space chess." Dixon glanced at Houseman and Withrop.
"From the looks of Cadet Astro, free-fall wrestling should be child's
play for him!"

Astro merely grinned.

"Mercuryball is pretty much like the old game of soccer," explained
Houseman. "But inside the ball is a smaller ball filled with mercury,
making it take crazy dips and turns. You have to be pretty fast even to
touch it."

"Sounds like you have to be a little Mercurian yourself," smiled Tom.

"You do," replied Dixon. "Oh, yes, you three play as a unit. Competition
starts in a few days. So if you've never played before, you might go
down to the gym and start practicing."

"You mentioned space chess," asked Roger. "What's that?"

"It's really nothing more than maneuvers. Space maneuvers," said Dixon.
"A glass case, a seven-foot cube, is divided by light shafts into
smaller cubes of equal shape and size. Each man has a complete space
squadron. Three model rocket cruisers, six destroyers and ten scouts.
The ships are filled with gas to make them float, and your power is
derived from magnetic force. The problem is to get a combination of
cruisers and destroyers and scouts into a space section where it could
knock out your opponent's ships."

"You mean," interrupted Astro, "you've got to keep track of all those
ships at once?"

"Don't worry, Astro," commented Roger quickly. "You use your muscles to
win for dear old 42-D in free-fall wrestling. Corbett here can pound
down the grassy field for a goal in mercuryball, and I'll do the
brainwork of space chess."

The three visiting cadets exchanged sharp glances.

"Everybody plays together, Manning," said Dixon. "You three take part in
each sport as a unit."

"Of course," nodded Roger. "Of course--as a unit."

The three cadets stood up, shook hands all around and left. Tom
immediately turned to Manning.

"What was the idea of that crack about brains?"

Manning slouched over to the window port and said over his shoulder, "I
don't know how you and your king-sized friend here passed the
classifications test, Corbett, and I don't care. But, as you say, we're
a unit. So we might as well make adjustments."

He turned to face them with a cold stare.

"I know this Academy like the palm of my hand," he