The (Sherlock Holmes) book contains a code which uses dancing men as glyphs.

The alphabet as given is not complete, lacking f, j, k, q, u, w, x and z, so those letters in the font are not due to Conan Doyle. The code required word endings to be marked by the dancing man representing the last letter to be holding a flag: these are coded as A-Z. thaTiStOsaYsentenceSiNthEcodElooKlikEthiS. In some cases, the man has no arms, making it impossible for him to hold a flag. In these cases, he is wearing a flag on his hat in the ‘character’.

The font is distributed as Metafont source; it works poorly in modern environments, and could do with expert attention (if you are interested, please contact the CTAN team for details).