I went to my bedroom and followed his advice. When I
returned with the pistol the table had been cleared, and
Holmes was engaged in his favourite occupation of scraping
upon his violin.

"The plot thickens," he said, as I entered; "I have just had
an answer to my American telegram. My view of the case is
the correct one."

"And that is?" I asked eagerly.

"My fiddle would be the better for new strings," he remarked.
"Put your pistol in your pocket. When the fellow comes speak
to him in an ordinary way. Leave the rest to me.
Don't frighten him by looking at him too hard."

"It is eight o'clock now," I said, glancing at my watch.

"Yes. He will probably be here in a few minutes. Open the
door slightly. That will do. Now put the key on the inside.
Thank you! This is a queer old book I picked up at a stall
yesterday -- `De Jure inter Gentes' -- published in Latin at
Liege in the Lowlands, in 1642. Charles' head was still firm
on his shoulders when this little brown-backed volume was
struck off."

"Who is the printer?"

"Philippe de Croy, whoever he may have been. On the fly-leaf,