The cold was now intense. For all his furred garments, there was no shutting out the frigidity. It ate to the very marrow. But Hal Dane's heart was hot within him, burning in its thrill of exultation. He was riding thirty-eight thousand feet above the earth, and riding with the whizzing speed of a bullet shot from a mighty gun. His plane, capable of two hundred miles an hour, had slid into a two-hundred-mile wind here in the upper air, and it was hurtling forward at the appalling speed of four hundred miles per hour.