"Oh! I'll write to Mr. Forbes of Ballarat," said Naball, making a note, "but if those notes are put in circulation, do you know of any means by which I can identify them?"
Keith shook his head, then suddenly gave a cry.
"Yes; I can tell you how to identify one of the notes."
"That will be quite sufficient," said the detective eagerly. "How?"
"That boy, Isaiah," said Stewart, "he's great on backing horses, and frequently tells me about racing. When I was making up my cash on that night, the notes were lying on the desk, and as the door of Mr. Lazarus' room was open, Isaiah was afraid to speak aloud about his tip, so he wrote it down."
"But how can that identify the bank-note?" asked the perplexed detective.
"Because the young scamp wrote his tip, 'Back Flat-Iron,' on the back of a ten-pound note."
"In pencil?" asked Naball.
"No; in ink!"
"So one of the notes that were stolen has the inscription 'Back Flat-Iron' on the back of it?"