"You must be mistaken?"

"I am not, sir."

"And if you met these two men, you would know them?"

"I would."

"Good;" I cried, laughing, "I see you have the very spirit for a detective. I must engage you as a member of our force."

"Joke if you like, sir. But I have still two good eyes, and I don't need spectacles to recognize people. Someone is spying on you, that's certain; and you should put some of your men to track them in turn."

"All right; I promise to do so," I said, to satisfy her. "And when my men get after them, we shall soon know what these mysterious fellows want of me."

In truth I did not take the good soul's excited announcement very seriously. I added, however, "When I go out, I will watch the people around me with great care."

"That will be best, sir."

My poor old housekeeper was always frightening herself at nothing. "If I see them again," she added, "I will warn you before you set foot out of doors."

"Agreed!" And I broke off the conversation, knowing well that if I allowed her to run on, she would end by being sure that Beelzebub himself and one of his chief attendants were at my heels.