Soon a motor truck approached the enclosure, its driver sounding his Klaxon for attention. Admitted by the watchman he drove to a position in front of the hangar, adjusted a pair of skids and helped unload his burden. Ned signed a receipt and the driver then made haste to depart. Just as the truck was leaving the grounds Jimmie appeared.
"Upon my honor as an expert," he cried, "that driver is our hungry spy of last night! How does it come he's out here?"
"That's strange!" mused Harry. "Where did the factory get him?"
"I don't know," admitted Jimmie, "but he's there all right!"
"The fellow's gone now," Harry exclaimed impatiently. "Let's get a little gasoline and turn the engine over. I'm getting anxious."
"Wait a bit," interrupted Ned. "Wouldn't it be a good idea to inspect the machine first? Maybe they forgot to put in the piston rings or something. Hurry-up jobs are sometimes neglected a little."
"Not in our shop!" boasted Harry. "This engine's all right!"
"Better look it over, anyway, Harry," suggested Jimmie. "Here's a wrench. It's easy to remove the cylinder heads and crank case cover."
Shortly a startled cry from Harry drew the boys to his side.
"Look, fellows," he shouted. "Look what's in here!"