Three voices, that of the caretaker no longer grumpy, urged him to explain. Too earnest to be proud of his deductions, Sandy spoke.
“When the hangar was first haunted, and we found chewing gum that the ghost had put there, as we thought,” he told an interested trio, “none of us could work out any answer to the puzzle.
“But stop and think of these things,” he continued, urging his two friends to use their own imaginations. “The amphibian was old-looking and didn’t seem to be much good, and the gas gauge was broken, and the chewing gum was quite fresh. That might look as though——”
“Some pilot was getting the ‘phib’ ready to fly and chewed gum as he worked and put the gauge out of order to keep anybody from knowing he had filled the gas tanks.”
“Good guess, Larry! It’s the way I work it out,” Dick added.
“Go on, young feller.” The caretaker was absorbed.
“Well,” Sandy grinned, “the chewing gum disappeared! Supposing the fellow we thought we saw vanishing really was there and got out some way. He’d know, from Jeff landing us and our going in, that the amphibian might not be usable when he’d need it——”
“So he went back and got the gum—but why?”
“He was getting that ready, Dick, for the emeralds—remember how Sandy discovered the place the imitations were hidden?”
“That’s so, Larry. Go on, Sandy. You’ve got a brilliant brain!”