“I have been guilty of several monographs. They are all upon technical subjects. Here, for example, is one “Upon the Distinction between the “Ashes of the Various Tobaccos”. In it I enumerate a hundred and forty forms of cigar, cigarette, and pipe tobacco, with coloured plates illustrating the difference in the ash. It is a point which is continually turning up in criminal trials, and which is sometimes of supreme importance as a clue.”
Arthur Conan Doyle
“The Sign of the Four”
View the manuscript @ Sherlockian.net
