F. J. Sittler (1827-1882) Little is known about the author but that he was a former French Post and Telegraph official. A law of 1866 granted the French public the use of cipher in telegrams. Sittler ‘s codebook first appeared in 1868. By 1919 it had reached its 36th edition and it would go on being used until the inter-war years. Secrecy was useful not only in private and business correspondence, but coded communication was also widely used by administrations and diplomatic services.
The Dictionnaire chiffré comprises 100 pages, each listing 100 numbered words, phrases or syllables arranged alphabetically, which can be coded by a four-digit number made up of the page number and its numbered entry. By mutual agreement, each user hand-numbers the pages identically from 00 to 99 in any order. Page numbers are changed at the correspondents' discretion. Superencipherment with addition or transposition of digits is also possible. At the end of each alphabetical section are vacant numbers for adding more words and phrases to adapt the manual to the need of the particular user.
The ‘Correspondance secrète’ method is explained in three pages.
A copy with scope for speculation as to its former use. In the handwritten additions, mention is made of the Brazilian government, the Minas Gerais government, the London and Brazilian Bank and the Vicomte de Sapucahy.