ore the major's desk, which he barely
topped. "The four of us have been working it out. Joe says they've done
powder metallurgy welds, back at his father's plant. Joe and Haney and
the Chief and me, we've been working out an idea."

Major Holt waited. His hands moved nervously on his desk. Joe looked at
Mike. Haney and the Chief regarded him warily. The Chief cocked his head
on one side.

"It'll take a minute to get it across," said Mike. "You have to think of
concrete first. When you want to make a cubic yard of concrete, you take
a cubic yard of gravel. Then you add some sand--just enough to fill in
the cracks between the gravel. Then you put in some cement. It goes in
the cracks between the grains of sand. A little bit of cement makes a
lot of concrete. See?"

Major Holt frowned. But he knew these four. "I see, but I don't
understand."

"You can weld metals together with powder-metallurgy powder at less than
red heat. You can take steel filings for sand and steel turnings for
gravel and powdered steel for cement--"

Joe jolted erect. He looked startledly at Haney and the Chief. And
Haney's mouth was dropping open. A great, dreamy light seemed to be
bursting upon him. The Chief regarded Mike with very bright eyes. And
Mike sturdily, forcefully, coldly, made a sort of speech in his small
and brittle voice.

Things could be made of solid steel, he said sharply, without rolling or
milling or die-casting the metal, and without riveting or arc-welding
the parts together. The trick was powder metallurgy. Very finely
powdered metal, packed tightly and heated to a relatively low
temperature--"sintered" is the word--becomes a solid mass. Even alloys
can be made by mixing powdered metals. The process had been used only
for small objects, but--there was the analogy to concrete. A very little
powder could weld much metal, in the form of turnings and smaller bits.
And the result would be solid steel!

Then Mike grew impassioned. There was a wooden mockup of a space ship in
the Shed, he said. It was an absolutely accurate replica, in wood, of
the ships that had been destroyed. But one could take castings of it,
and use them for molds, and fill them with powder and filings and
turnings, and heat them not even red-hot and there would be steel hulls
in one piece. Solid steel hulls! Needing no riveting nor anything
else--and one could do it fast! While the first hull was fitting out a
second could be molded----

The Chief ro