the days
were still lengthening. Once in the White Sea, the _Denver_ was made
ready for instant action. A huge amphibian plane was hoisted in sections
from the hold and mechanics started to assemble it. Dr. Bird spent most
of his time working on some instruments he had assembled in the radio
room.

"This is an ultra-short wave detector," he explained to Carnes. "It will
receive vibrations to the lowest limit of waves that we have ever been
able to measure. The X-ray is high on the scale and even the cosmic ray
is far above its lower limit of detection. We are hunting for an
electro-magnet, the largest and strangest electro-magnet that has ever
been constructed. Perhaps it would be more accurate to say that we are
seeking for a generator of magnetic force. It does not generate the
ordinary magnetism which attracts iron and steel, nor the special type
of magnetism which we call gravity, but something between the two. It
attracts the sun enough to disturb the tilt of the earth's axis, but not
enough to pull the earth out of its orbit. Such a device should give out
a wave that can be detected, if we get a receiver delicate enough and
operating on the right wave length."

* * * * *

He spent hours improving and refining the apparatus, but in the end he
confessed himself beaten.

"It's no use, Carnes," he said the day after Cape Kanin faded from view
to the north. "Either the apparatus we are seeking gives out no wave
that we can detect or my apparatus is faulty. Luckily we have other
things to guide us."

"What are they, Doctor?"

"The facts that Saranoff must have easy transportation and a source of
power. The first precludes him from locating his station far from the
sea-coast and the second indicates that it will be near a river or other
source of power. The only Russian points on the sixty-fifth parallel
that are open to water transport are the Gulf of Anadyr, north of
Kamchatka, and the vicinity of Archangel. I passed up Kamchatka because
it would mean too long a haul through unfriendly waters from Leningrad
and because there is not much water power. Archangel is easy of access
at this time of the year and it has the Dwina river for power. That will
be our first line of search."

"We will explore by plane, of course?"

"Certainly. We wouldn't get far on foot, especially as neither of us
speaks Russian. We'll head south for another day and then-- What's that?"

* *