She tried to control her tears.

“We’re in a fix, yes!” he said insistently.  “It does look like there may be a flock of other space ship landings within days.  But the monsters don’t want to kill people.  They want a world with people working for them, not dead.  They’ve proved it.  They’ll avoid massacres.  They won’t let the humans who’re their allies destroy the people they want alive and useful.”

Jill clenched her fists.  “But it would be better to be dead than like that!”

“But wait!” protested Lockley.  “We’ve duplicated the terror beam.  Do you think they’ll leave it at that?  The men who know how to do it will be scattered to a dozen or a hundred places, so they can’t possibly all be found, and they’ll keep on secretly working until they’ve made the beams and a protection against them and then something more deadly still!  We humans can’t be conquered!  We’ll fight to the end of time!”

“But you yourself,” said Jill desperately, “you said there couldn’t be a defense against the beam!  You said it!”

“I was discouraged,” he protested.  “I wasn’t thinking straight.  Look!  With no equipment at all, I found out how to detect the stuff before it was strong enough to paralyze us.  You know that.  The scientists will have equipment and instruments, and now that they’ve got the beam they’ll be able to try things.  They’ll do better than I did.  They can try heterodyning the beam.  They can try for interference effects.  They may find something to reflect it, or they can try refraction.”

He paused anxiously.  She sobbed, once.  “But other weapons—­”

“There may not be any.  And there’s bound to be some trick of refraction that’ll help.  It thins out at the edges now.  That’s how we get warning of it.  It’s refracted by ions in the air.  That’s why it isn’t a completely tight beam.  Ions in the air act like drops of mist; they refract sunshine and make rainbows after rain.  And we got the smell-effect first.  That proves there’s refraction.”

He watched her face.  She swallowed.  What he’d said was largely without meaning.  Actually, it wasn’t even right.  The evidence so far was that the nerves of smell were more sensitive than the optic nerves or the auditory ones, while nerves to bundles of muscle were less sensitive still.  But Lockley wasn’t concerned with accuracy just now.  He wanted to reassure Jill.

Then his eyes widened suddenly and he stared past her.  He’d been speaking feverishly out of emotion, while a part of his mind stood aside and listened.  And that detached part of his mind had heard him say something worth noting.

He stood stock-still for seconds, staring blankly.  Then he said very quietly, “You made me think, then.  I don’t know why I didn’t, before.  The terror beam does scatter a little, like a searchlight beam in thin mist.  It’s scattered by ions, like light by mist-droplets.  That’s right!”

He stopped, thinking ahead.  Jill said challengingly, “Go on!” Again what he’d said had little meaning to her, but she could see that he believed it important.