"It's a thing which I did not know until that moment, but it's
the truth. If hard-packed earth is dug up and repacked air gets
into it, and if one pours water on the place air bubbles will
come up."

He did not go on, and I flung at him the big query in his story.

"And you found the plates there?"

"Yes, Sir Henry," he replied, "in the false bottom of an old
steamer trunk."

"And the hobo got the money?"

"Certainly," he answered. "I put it into his hand, and let him
go with it, as I promised."

Again he was silent, and I turned toward him in astonishment.

"Then," I said, "why did you begin this story by saying the hobo
faked you? I don't see the fake; he found the plates and he was
entitled to the reward."

Walker put his hand into his pocket, took out a leather case,
selected a paper from among its contents and handed it to me.
"I didn't see the fake either," he said, "until I got this
letter."

I unfolded the letter carefully. It was neatly written in a hand