“Dr. Barretti, what is your profession?”

“I believe that I might describe myself, without too much presumption, as a finger-print expert.”

There was no trace of accent in Dr. Barretti’s finely modulated voice, and only the neatest touch of humourous deprecation.

“The greatest authority in the world to-day, aren’t you, Doctor?”

“It would ill become me to say so, sir, and I might find an unflattering number to disagree with me.”

“Still, it’s an undisputed fact. How long has finger-printing been your occupation?”

“It has been both my occupation and my hobby for about thirty-two years.”

“You started to make a study of it then?”

“A little before that. I studied at the time, however, with Sir Francis Galton in England and Bertillon in France. I also did considerable experimental work in Germany.”

“Sir Francis Galton and Bertillon were the pioneers in the use of finger prints for identification, were they not?”