WILKINS, John. Mercury, or the Secret and Swift Messenger: Showing How a Man May With Privacy and Speed Communicate His Thoughts to a Friend at Any Distance
London: I. Norton for John Maynard and Timothy Wilkins, 1641.

First edition of “the most important of early English works on cryptography” (Galland, p.201).

“A succinct volume, very well grounded in the classics, Mercury introduced the words cryptographia (defined by Wilkins as ‘secrecy writing’) and cryptologia (‘secrecy of speech’) into English. The author reserved the term cryptomeneses, or ‘private intimations,’ for the art of secret communication in general. In addition to summing up the knowledge of the time, Wilkins depicted three types of geometrical cipher, a mystifying system in which a message is represented by dots, lines or triangles. The letters of the alphabet, in normal or mixed order, were written out at normal spatial intervals; these served as the key. This line of letters was held at the top of a sheet of paper, and the message was spelled out by marking a dot for each plaintext letter underneath that letter in the key alphabet, each dot lower than its predecessor. The dots could then be connected by twos to form what would look like a graph – or they could be left as dots. The receiver, who had an identically proportioned key, noted the positions of the dots, the ends of the lines, or the apexes of the triangles against the alphabetical scale to read the plaintext.” (Kahn, p. 155).

There had been diplomatic cipher books in manuscript since Elizabethan times for envoys and military men, but this was the first printed book devoted to the subject in English. At the end Wilkins deals with modes of rapid communication, from carrier pigeons to smoke signals. He calls this ‘tachymenysis, or the art of swift information’.

J. S. Galland, An Historical and Analytical Bibliography of the Literature of Cryptology, 1945; D. Kahn, The Codebreakers. The Story of Secret Writing, 1996; Wing W2202.

8vo: 163 x 107 mm. The text complete with 95 leaves, but paginated pp. [xiv], 1-48, 65-80, 83-98, 81-128, 127-169, 180, without the preliminary blank [A1] and the terminal blanks [M7-8] (as usual). Title and text within ruled borders. Contemporary calf, spine with some professional leather restoration, inner hinges strengthened with Japan paper. Ownership inscription, James Haig dated July 1770, to title and endpaper. In all a very good copy.