ng at the edge of the room, rose slowly in his
seat. "You've got the cart before the horse," he said. "You've got a
nice theory all set up and you want us to beat our brains out trying to
prove it. Now, take me. I've got a theory that little green men from
Mars have landed and are being sucked into the air intake of the
engines. Prove my theory first, why don't you?"

Ken grinned good-naturedly. "I stand corrected, but I won't back down
very far. I won't suggest we try to prove the connection with the comet,
but I do propose to set up some experiments to discover if there is any
relationship. If there is, then what it is. Does that suit you?"

"I'll go along with that. How do you propose to go about it?"

"Let's find out where the rest stand," said Ken. "How about it, you
guys?"

"I'll go for it," said Ted, "as long as we aren't out to prove a
medieval superstition."

One by one, the others nodded agreement. Joe Walton said intensely,
"We'll find out whether it's superstition or not! There's no other
possible cause, and we'll prove it before we're through."

Ken smiled and waved him down. "We're working on a hypothesis only.
Anyway, here's what I have to suggest by way of procedure: Since the
tail of the comet is so rarefied, there aren't many molecules of it in
the atmosphere of this entire valley. I don't know just what the
mathematical chances of getting a measurable sample are. Maybe you can
work out some figures on it, Dave. We'll have to handle an enormous
volume of air, so let's get a blower as large as we can get our hands on
and funnel the air through some electrically charged filters. We can
wash down these filters with a solvent of some kind periodically and
distill whatever has collected on them."

"You won't get enough to fill the left eye of a virus suffering from
arrested development," said Ted.

"We'll find out when we get set up," said Ken. "My father has agreed to
give us access to the electron microscope at the college. Maybe we can
use their new mass spectrograph to help analyze whatever we collect."

"If we knew how to use a mass spectrograph," said Ted.

"He's offered to let one of the teaching fellows help us."

"What will all this prove, even if we do find something?" Dave asked.
"You'll get all kinds of lines from a spectrogram of atmospheric dust.
So what?"

"If we should get some lines that we can't identify, and if we should
get those same lines from metallic specimens taken fro