savages--whatever they are--they probably never come within five
kilometers of the falls. Many primitive peoples think that waterfalls
are inhabited by demons, and maybe these folks are afflicted the same
way."

"We don't know much about our new world yet, do we?"

"We sure don't--and I'm not particularly keen on finding out much more
about it until we get organized for trouble, either. Well, here we
are--just like getting back home to see the 'Hope,' isn't it?"

"It _is_ home, and will be until we get one of our own on earth," and
after Stevens had read his meters, learning with satisfaction that the
full current was still flowing into the accumulators, he began to cut
up the meat.

"Now that you've got the power-plant running at last, what next?" asked
Nadia, piling the cuts in the freezer.

"Brandon's ultra-radio comes next, but it's got more angles to it than
a cubist's picture of a set of prisms; so many that I don't know where
to begin. There, that job's done--let's sit down and I'll talk at you
awhile. Maybe between us we can figure out where to start. I've got
everything to build it lined up except for the tube, but that's got me
stopped cold. You see, fields of force are all right in most places, but
I've got to have one tube, and it's got to have the hardest possible
vacuum. That means a mercury-vapor super pump. Mercury is absolutely
the only thing that will do the trick and the mercury is one thing
that is conspicuous by it's absence in these parts. So are tungsten for
filaments, tantalum for plates, and platinum for leads; and I haven't
found anything that I can use as a getter, either--a metal, you know, to
flash inside the tube to clean up the last traces of atmosphere in it."

"I didn't suppose that such a simple thing as a radio tube could hold
you up, after the perfectly unbelievable things that you have done
already--but I see now how it could. Of course, the tubes in our
receiver over there are too small?"

"Yes, they are only receiver and communicator tubes, and I need a
high-power transmitting tube--a fifty-kilowatter, at least. I'd give
my left leg to the knee joint for one of those big water-cooled,
sixty-kilowatt ten-nineteens right now--it would save us a lot of
grief."

"Maybe you could break up those tubes and use the plates and so on?"

"I thought of that, but it won't work--there isn't half enough metal
in the lot, and the filaments in particular are so tiny that I couldn't
possi