With an exclamation of alarm, Purdy advanced his throttle until the three motors of his plane roared at full capacity. For a moment his air-speed picked up, but the gain was only momentary. As he watched, the meter dropped to zero, although the propellers still whirled at top speed. His altimeter showed that he was gradually losing elevation. He stood up and looked over the side of his plane. The ground below him was stationary as far as forward progress was concerned, but it was slowly rising to meet him. He fumbled at the release ring of his parachute but another glance at the ground made him hesitate. It was not more than three hundred feet below him. "I must be dreaming!" he cried. The ground was no longer stationary. For some unexplained reason he was going backward. The motors were still roaring at top speed. Purdy dropped back into his seat in the cockpit. With his ailerons set for maximum lift he coaxed every possible revolution from his laboring motors. For several minutes he strained at the controls before he cast a quick glance over the side. His backward speed had accelerated and the ground was less than fifty feet below him. It was too close for a parachute jump. "As slow as I'm falling, I won't crack much, anyway," he consoled himself. He reached for his switch and the roar of the motors died away in silence. The plane gave a sickening lurch backwards and down for an instant. Purdy again leaned over the side. He was no longer going either forward or back but was sinking slowly down. He looked at the ground directly under him. A cry of horror came from his lips. He sat back mopping his brow. Another glance over the side brought an expression of terror to his white face and he reached for the heavy automatic pistol which hung by the side of the control seat. * * * * * "He cleared Bellefonte at nine in the morning, Dr. Bird" said Inspector Dolan of the Post Office Department, "and headed toward Philipsburg. He never arrived. By ten we were alarmed and by eleven we had planes out searching for him. They reported nothing. He must have come to grief within a rather restricted area, so we sent search parties out at once. That was two weeks ago yesterday. No trace of either him or his plane has been found." "The flying conditions were good?" "Perfect. Also, Purdy is above suspicion. He has been flying the mail on the western runs for three years. This is his first accident. He was carrying nothing of unusual value." "Are there any local conditions unfavorable to flying?" "None at all. It is much uninhabited country, but there is no reason why it shouldn't be safe country to fly over."