Tobacco as Evidence


“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 @