t really believe that they knew enough. I don't quite know what to
think. They may be easy and they may not; but, easy or hard to get,
we're loaded for bear and I'm plenty sure that we'll pull their corks."

"So am I, really, but we must consider every contingency. We know that
they had at least a detector of fifth-order rays...."

"And if they did have an analytical detector," Seaton interrupted,
"they'll probably slap a ray on us as soon as we stick our nose out of
the Galaxy!"

"They may--and even though I do not believe that there is any
probability of them actually doing it, it will be well to be armed
against the possibility."

"Right, old top--we'll do that little thing!"

* * * * *

Uneventful days passed, and true to Seaton's calculations, the awful
acceleration with which they had started out could not be maintained. A
few days before the edge of the Galaxy was reached, it became necessary
to cut off the molecular drive, and to proceed with an acceleration
equal only to that of gravitation at the surface of the Earth. Tired of
weightlessness and its attendant discomforts to everyday life, the
travelers enjoyed the interlude immensely, but it was all too short--too
soon the stars thinned out ahead of "_Three's_" needle prow. As soon as
the way ahead of them was clear, Seaton again put on the maximum power
of his terrific bars and, held securely at the console, set up a long
and involved integral. Ready to transfer the blended and assembled
forces to a plunger, he stayed his hand, thought a moment, and turned to
Crane.

"Want some advice, Mart. I'd thought of setting up three or four courses
of five-ply screen on the board--a detector screen on the outside of
each course, next to it a repeller, then a full-coverage ether-ray
screen, then a zone of force, and a full-coverage fifth-order ray-screen
as a liner. Then, with them all set up on the board, but not out, throw
out a wide detector. That detector would react upon the board at impact
with anything hostile, and automatically throw out the courses it found
necessary."

"That sounds like ample protection, but I am not enough of a
ray-specialist to pass an opinion. Upon what point are you doubtful?"

"About leaving them on the board. The only trouble is that the reaction
isn't absolutely instantaneous. Even fifth-order rays would require a
millionth of a second or so to set the courses. Now if they were using
ether waves