On our arrival at his chambers he immediately handed over the camera to
Polton with a few curt directions as to the development of the plates,
and, lunch being already prepared, we sat down at the table without
delay.

We had proceeded with our meal in silence for some time when Thorndyke
suddenly laid down his knife and fork and looked into my face with a
smile of quiet amusement.

"It has just been borne in upon me, Jervis," said he, "that you are the
most companionable fellow in the world. You have the heaven-sent gift of
silence."

"If silence is the test of companionability," I answered, with a grin,
"I think I can pay you a similar compliment in even more emphatic
terms."

He laughed cheerfully and rejoined--

"You are pleased to be sarcastic, I observe; but I maintain my position.
The capacity to preserve an opportune silence is the rarest and most
precious of social accomplishments. Now, most men would have plied me
with questions and babbled comments on my proceedings at Scotland Yard,
whereas you have allowed me to sort out, without interruption, a mass of
evidence while it is still fresh and impressive, to docket each item and
stow it away in the pigeonholes of my brain. By the way, I have made a
ridiculous oversight."

"What is that?" I asked.