"What was the man's appearance, sir? The servant could not tell me."

"So much the better," thought Hartley, with satisfaction.

"He was a little taller than myself, I should say," he answered, "and I believe his hair was brown"—Hartley's was black. "I am sorry I can't remember more particularly."

"That is something. Thank you, sir. I wish I knew where the cab went."

"I think I can tell you that. I came down into the street before the cab drove away, and I heard the gentleman referred to say, in a low voice, 'Drive to Harlem.'"

"Thank you, sir," said Dan, gratefully. "That puts me on the right track. I shall know where to search now."

"I wish I could tell you more," said Hartley, with a queer smile.

"Thank you, sir."

"If you find your little sister, I should be glad if you would let me know," continued Hartley, chuckling inwardly.