Beside them, and apparently superintending their work, was the old man whom Jack knew as Dr.Robinson.
He applied his ear to the crevice, and heard these words: "This lot is rather better than the last, Jones.

We can't be too careful, or the detectives will interfere with our business.

Some of the last lot were rather coarse." "I know it, sir," answered the man addressed as Jones.
"There's nothing the matter with this," said the old man.

"There isn't one person in a hundred that would suspect it was not genuine." Jack pricked up his ears.
Looking through the crevice, he ascertained that it was a bill that the old man had in his hand.
"They're counterfeiters," he said, half audibly.
Low as the tone was, it startled Dr.Robinson.
"Ha!" said he, startled, "what's that ?" "What's what, sir ?" said Jones.
"I thought I heard some one speaking." "I didn't hear nothing, sir." "Did you hear nothing, Ferguson ?" "No, sir." "I suppose I was deceived, then," said the old man.
"How many bills have you there ?" he resumed.
"Seventy-nine, sir." "That's a very good day's work," said the old man, in a tone of satisfaction.

"It's a paying business." "It pays you, sir," said Jones, grumbling.
"And it shall pay you, too, my man, never fear!" Jack had made a great discovery.