No. 77B, Brook Street, was one of those dingy and yet imposing houses, dun-coloured and flat-faced, with the intensely respectable and solid air which marks the Georgian builder.  As I alighted from the cab, a young man came out of the door and walked swiftly down the street.  In passing me, I noticed that he cast an inquisitive and somewhat malevolent glance at me, and I took the incident as a good omen, for his appearance was that of a rejected candidate, and if he resented my application it meant that the vacancy was not yet filled up.  Full of hope, I ascended the broad steps and rapped with the heavy knocker.

A footman in powder and livery opened the door.  Clearly I was in touch with the people of wealth and fashion.

“Yes, sir?” said the footman.

“I came in answer to——­”

“Quite so, sir,” said the footman.  “Lord Linchmere will see you at once in the library.”

Lord Linchmere!  I had vaguely heard the name, but could not for the instant recall anything about him.  Following the footman, I was shown into a large, book-lined room in which there was seated behind a writing-desk a small man with a pleasant, clean-shaven, mobile face, and long hair shot with grey, brushed back from his forehead.  He looked me up and down with a very shrewd, penetrating glance, holding the card which the footman had given him in his right hand.  Then he smiled pleasantly, and I felt that externally at any rate I possessed the qualifications which he desired.

“You have come in answer to my advertisement, Dr. Hamilton?” he asked.

“Yes, sir.”

“Do you fulfil the conditions which are there laid down?”

“I believe that I do.”

“You are a powerful man, or so I should judge from your appearance.

“I think that I am fairly strong.”

“And resolute?”

“I believe so.”

“Have you ever known what it was to be exposed to imminent danger?”

“No, I don’t know that I ever have.”

“But you think you would be prompt and cool at such a time?”

“I hope so.”

“Well, I believe that you would.  I have the more confidence in you because you do not pretend to be certain as to what you would do in a position that was new to you.  My impression is that, so far as personal qualities go, you are the very man of whom I am in search.  That being settled, we may pass on to the next point.”

“Which is?”

“To talk to me about beetles.”

I looked across to see if he was joking, but, on the contrary, he was leaning eagerly forward across his desk, and there was an expression of something like anxiety in his eyes.

“I am afraid that you do not know about beetles,” he cried.

“On the contrary, sir, it is the one scientific subject about which I feel that I really do know something.”

“I am overjoyed to hear it.  Please talk to me about beetles.”