With an effort, Hal forced his mind away from morbid thoughts. He concentrated on his maps and instruments. Already, he had come over two thousand miles. With every whir of his motor he was ticking off more miles. A great longing rose in him to ride the high air currents once again, that would mean real speed. But he dared not risk his plane another time in the icy grip of the stratosphere. He had wracked the engine enough already. Another such battle with the ice sheath and with over-speed might tear the motor bodily from the machine.