on guard.
We're just about within reach of a light copper-driven ray right now,
but it's a cinch they can't send anything heavy this far, and if they
think we're overconfident, so much the better."

"There," he continued, after a few minutes at the keyboard. "All set. If
they put a detector on us, I've got a force set to make a noise like a
New York City fire siren. If pressed, I'd reluctantly admit that in my
opinion we're carrying caution to a point ten thousand degrees below the
absolute zero of sanity. I'll bet my shirt that we don't hear a yip out
of them before we touch 'em off. Furthermore...."

* * * * *

The rest of his sentence was lost in a crescendo bellow of sound.
Seaton, still at the controls, shut off the noise, studied his meters
carefully, and turned around to Crane with a grin.

"You win the shirt, Mart. I'll give it to you next Wednesday, when my
other one comes back from the laundry. It's a fifth-order detector ray,
coming in beautifully on band forty-seven fifty, right in the middle of
the order."

"Aren't you going to put a ray on 'em?" asked Dorothy in surprise.

"Nope--what's the use? I can read theirs as well as I could one of my
own. Maybe they know that too--if they don't we'll let 'em think we're
coming along, as innocent as Mary's little lamb, so I'll let their ray
stay on us. It's too thin to carry anything, and if they thicken it up
much I've got an axe set to chop it off." Seaton whistled a merry
lilting refrain as his fingers played over the stops and keys.

"Why, Dick, you seem actually pleased about it." Margaret was plainly
ill at ease.

"Sure am. I never did like to drown baby kittens, and it kinda goes
against the grain to stab a guy in the back, when he ain't even looking,
even if he is a Fenachrone. If they can fight back some I'll get mad
enough to blow 'em up happy."

"But suppose they fight back too hard?"

"They can't--the worst that can possibly happen is that we can't lick
them. They certainly can't lick us, because we can outrun 'em. If we
can't get 'em alone, we'll beat it back to Norlamin and bring up
re-enforcements."

"I am not so sure," Crane spoke slowly. "There is, I believe, a
theoretical possibility that sixth-order rays exist. Would an extension
of the methods of detection of fifth-order rays reveal them?"

"_Sixth_? Sweet spirits of niter! Nobody knows anything about them.
However, I've had one surprise already, so