"You say we're back at the surface, Carter? How can that be? Howlong have I been unconscious?"

"Not long. We turned in the ice stratum. Don't you recall thesudden whirling of our seats? After that the drill was far above youinstead of below. We didn't notice it at the time; but I recallit now."

"You mean to say that we turned back in the ice stratum, David?That is not possible. The prospector cannot turn unless its noseis deflected from the outside--by some external force or resistance--thesteering wheel within would have moved in response. The steeringwheel has not budged, David, since we started. You know that."

I did know it; but here we were with our drill racing in pure air,and copious volumes of it pouring into the cabin.