Chapter 13

Dr. Armitage knew, from the repeated failures of his colleagues, that the riddle was a deep and complex one, and that no simple mode of solution could merit even a trial. All through late August he fortified himself with the massed lore of cryptography, drawing upon the fullest resources of his own library, and wading night after night amidst the arcana of Trithemius' _Poligraphia_, Giambattista Porta's _De Furtivis Literarum Notis_, De Vigenere's _Traité des Chiffres_, Falconer's _Cryptomenysis Patefacta_, Davys' …