"His fountain pen might have leaked," suggested Mr. Jackson.

"In that case the ink spot would be on the outside of the map, and
not on the inside," declared Tom, with the instinct of a detective.
"Unless he had the map folded in his pocket with the inside surface
on the outside, the ink couldn't have gotten on. Besides, Andy
always carries his fountain pen in his upper vest pocket, and that
pocket is too small to hold the map. No, I'm almost positive that
Andy or his father have sneakingly made a copy of this map!"

"I'm sorry to have to admit that Mr. Foger is capable of such an
act," spoke Mr. Swift, "but I believe it is true."

"And here is another thing," went on the young inventor, who was now
closely scanning the parchment through a powerful magnifying glass,
"do you see those tiny holes here and there, Mr. Jackson?"

"Yes," answered the engineer.

"Were they there before, Abe?" went on Tom, calling the old miner's
attention to them.

"Nary a one," was the answer. "It looks as if some one had been
sticking pins in th' map."

"Not pins," said Tom, "but the sharp points of a pair of dividers,
or compasses, for measuring distances. Andy, or whoever made a copy
of the map, used the dividers to take off distances with. This
clinches it, in my mind."