stuffing himself with good
honest food. There was a glass port beside him, and Joe caught a glimpse
of illimitable distances filled with cloud and sky and sea.

Mike nodded. He didn't offer to help Joe walk. That wouldn't have been
practical. He waited until Joe sank into a seat opposite.

"Good sleep?" asked Mike.

"I guess so," said Joe. He added ruefully, "It hurts to nod, and I think
it would hurt worse to shake my head. What's the matter with me, Mike? I
didn't get banged up in the landing!"

"You got banged up before you landed," said Mike. "Worse than that, you
spent better than six weeks out of gravity, where in an average day you
took less actual exercise than a guy in bed with two broken legs!"

Joe eased himself back into his chair. He felt about 600 years old.
Somebody poked a head into view and withdrew it. Joe lifted his arm and
regarded it.

"Weighty! I guess you're right, Mike."

"I know I'm right!" said Mike. "If you spent six weeks in bed you'd
expect to feel wobbly when you tried to walk. Up on the Platform you
didn't even use energy to stand up! We didn't realize it, but we were
living like invalids! We'll get our strength back, but next time we'll
take measures. Huh! Take a trip to Mars in free fall, and by the time a
guy got there his muscles'd be so flabby he couldn't stand up in
half-gravity! Something's got to be done about that, Joe!"

Joe said sombrely, "Something's got to be done about space ships before
that comes up again!"

Somebody appeared with a tray. There was food on it. Smoking hot food.
Joe looked at it and knew that his appetite, anyhow, was back to Earth
normal.

"Thanks!" he mumbled appreciatively, and attacked the food.

Mike drank his coffee. Then he said, "Joe, do you know anything about
powder metallurgy?"

Joe shrugged. It hurt. "Powder metallurgy? Yes, I've seen it used, at my
father's plant. They've made small precision parts with it. Why?"

"D'you know if anybody ever made a weld with it?" asked Mike.

Joe chewed. Then he said:

"I think so. Yes. At the plant they did. They had trouble getting the
surfaces properly cleaned for welding. But they managed it. Why?"

"One more question," said Mike tensely. "How much Portland cement is
used to make a cubic yard of concrete?"

"I wouldn't know," admitted Joe. "Why? What's all this about?"

"Haney and the Chief. Those two big apes have been kidding me--as long
as they could stay awake--for what happened to