“Somebody must have got in, put some sort of dope in Dolan’s food or water, and also clogged the pipes,” said Ned. “Right!” snapped out Tom. “But we aren’t beaten yet!” And they were not. By hard work the young inventor got the other oil line cleaned, and then the _Osprey_ at once picked up speed. However, much valuable time had been lost, and Tom was anxious lest the motors might have been permanently damaged by running without sufficient oil. But they must carry on now, at all hazards, for they were within striking distance of their goal. They at last settled down into the San Francisco landing field after dark—a poor record, nearly twenty hours having been consumed since starting. “Lucky I’m not on a strict time limit for these six trips,” commented Tom as, tired and exhausted from work and worry, he climbed out of the cockpit, followed by Ned. “Jacks didn’t stipulate that we must keep to the sixteen-hour schedule for these six trips. His only condition was that we must fly continually from coast to coast, with landings only at Chicago and Denver, and we’ve done that.” “Through good luck and management,” commented Ned. “But we’ve got to be mighty careful, Tom, on the last trip back. They’ll be out to do us if they can and spoil our chances of getting that hundred thousand dollars from Jacks.” “You said it! Well, we’ll do the best we can.” Extraordinary precautions were taken about the hangar that night. Men continually patrolled the place, and even newspaper reporters and photographers were looked upon with suspicion. None but those with unquestionable credentials were allowed within the enclosure. Tom had intended starting back to New York about three days after his arrival, but the accident to the oil line decided him to have the cylinders reground and new pistons put in. “We want to make the last lap a record,” he said. The delay was nerve-racking but it could not be helped. Tom was in communication with his father and Mary, and they, too, were eager for his success. All was well at home, Mary reported, and close guard was being kept on the Long Island hangar. “They may try to blow us up when we make our last landing,” said Tom grimly, to his manager. “They’re equal to it,” was Ned’s answer. “What about Chicago and Denver?” “I’m wiring the men there to be on the watch.” At last the overhauling of the _Osprey’s_ motor was finished, and after a test preparations for the trip back were made. Word that this was to be the final test of the airline express had been broadcast, and the papers all over the country were on the alert for news. It was almost like a presidential election. In the half-light of a cold dawn Tom and his friends took the air from the San Francisco field. As they mounted upward Ned happened to glance at a calendar hanging on the wall of the car. “Did you know that, Tom?” he asked. “Know what?” “That this is Friday the thirteenth?” “Well, what of it?” asked the inventor. “Don’t you believe in luck?”