Slowly it rose once more until we were convinced that at last we
were nearing the molten interior of the earth. At four hundred
miles the temperature had reached 153 degrees. Feverishly I watched
the thermometer. Slowly it rose. Perry had ceased singing and
was at last praying.

Our hopes had received such a deathblow that the gradually
increasing heat seemed to our distorted imaginations much greater
than it really was. For another hour I saw that pitiless column
of mercury rise and rise until at four hundred and ten miles it
stood at 153 degrees. Now it was that we began to hang upon those
readings in almost breathless anxiety.

One hundred and fifty-three degrees had been the maximum temperature
above the ice stratum. Would it stop at this point again, or would
it continue its merciless climb? We knew that there was no hope,
and yet with the persistence of life itself we continued to hope
against practical certainty.

Already the air tanks were at low ebb--there was barely enough of
the precious gases to sustain us for another twelve hours. But
would we be alive to know or care? It seemed incredible.

At four hundred and twenty miles I took another reading.

"Perry!" I shouted. "Perry, man! She's going down! She's going
down! She's 152 degrees again."

"Gad!" he cried. "What can it mean? Can the earth be cold at the