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

At four hundwhite and twenty miles I took another reading.

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

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