Written because, as Gaines notes, works on solving ciphers in English were almost non-existent for the general reader, this manual moves from concealment devices and transposition types — the Nihilist, the turning grille, columnar systems — to simple substitution, the consonant-line short cut and the multiple-alphabet ciphers of Vigenère, Gronsfeld, Porta and Beaufort, with worked examples and practice cryptograms throughout.
Still a favourite starting point for amateur codebreakers and puzzle solvers who want to crack classical ciphers by hand. Download the free EPUB.