ndall. Therefore they won't."

"What did you mean about gamma rays, Buck?"

"Mercury will stop them and the Commander here intends to have the
refitted ships built so that the engine room and control room are one,
and completely surrounded by the mercury tanks. The men will be
protected against the gamma rays."

"Won't the rays affect the power stored in the mercury--perhaps release
it?"

"We tried it out, of course, and while we can't get the intensities we
expect, and can't really make any measurements of the gamma-ray energy
impinging on the mercury--it seems to absorb, and store that energy!"

"What's next on the program, Buck?"

"Finish those ships I have building. And I want to do some more
development work. The Stranger will return within six months now, I
believe. It will take all that time, and more for real refitting of the
IP ships."

"How about more forts--or banks, whichever you want to call them. Mars
isn't protected."

"Mars is abandoned," replied General Logan seriously. "We haven't any
too much to protect old Earth, and she must come first. Mars will, of
course, be protected as best the IP ships can. But--we're expecting
defeat. This isn't a case of glorious victory. It will be a case of hard
won survival. We don't know anything about the enemy--except that they
are capable of interstellar flights, and have atomic energy. They are
evidently far ahead of us. Our battle is to survive till we learn how to
conquer. For a time, at least, the Strangers will have possession of
most of the planets of the system. We do not think they will be able to
reach Earth, because Commander McLaurin here will withdraw his ships to
Earth to protect the planet--and the great 'Lunar Bank' will display its
true character."

VII

Faragaut looked unsympathetically at Buck Kendall, as he stood glaring
perplexedly at the apparatus he had been working on.

"What's the matter, Buck, won't she perk?"

"No, damn it, and it should."

"That," pointed out Faragaut, "is just what you think. Nature thinks
otherwise. We generally have to abide by her opinions. What is it--or
what is it meant to be?"

"Perfect reflector."

"Make a nice mirror. What else, and how come?"

"A mirror is just what I want. I want something that will reflect _all_
the radiation that falls on it. No metal will, even in its range of
maximum reflectivity. Aluminum goes pretty high, silver, on some ranges,
a bit higher. But none of them re