Galaxy. Outside it, in free space, of course we can open her up
again. Then, too, our acceleration is not exactly four times theirs,
only three point nine one eight six. On the other hand, we don't have to
catch them to go to work on them. We can operate very nicely at five
thousand light-centuries. So there you are--it'll probably be somewhere
between thirty-nine and forty-one days, but it may be a day or so more
or less."

"How do you know they are using copper?" asked Margaret. "Maybe their
scientists stored up some uranium and know how to use it."

"Nope, that's out like a light. First, Mart and I saw only copper bars
in their ship. Second, copper is the most efficient metal found in
quantity upon their planet. Third, even if they had uranium or any metal
of its class, they couldn't use it without a complete knowledge of, and
ability to handle, the fourth and fifth orders of rays."

"It is your opinion, then, that destroying this last Fenachrone vessel
is to prove as simple a matter as did the destruction of the others?"
Crane queried, pointedly.

"Hm-m-m. Never thought about it from that angle at all, Mart.... You're
still the ground-and-lofty thinker of the outfit, ain't you? Now that
you mention it, though, we may find that the Last of the Mohicans ain't
entirely toothless, at that. But say, Mart, how come I'm as wild and
cock-eyed as I ever was? Rovol's a slow and thoughtful old codger, and
with his accumulation of knowledge it looks like I'd be the same way."

"Far from it," Crane replied. "Your nature and mine remain unchanged.
Temperament is a basic trait of heredity, and is neither affected nor
acquired by increase of knowledge. You acquired knowledge from Rovol,
Drasnik, and others, as did I--but you are still the flashing genius and
I am still your balance wheel. As for Fenachrone toothlessness: now that
you have considered it, what is your opinion?"

"Hard to say. They didn't know how to control the fifth order rays, or
they wouldn't have run. They've got real brains, though, and they'll
have something like seventy days to work on the problem. While it
doesn't stand to reason that they could find out much in seventy days,
still they may have had a set-up of instruments on their detectors that
would have enabled them to analyze our fields and thus compute the
structure of the secondary projector we used there. If so, it wouldn't
take them long to find out enough to give us plenty of grief--but I
don'