“Various are the methods which have been devised for transmitting secret information from one individual to another, by means of writing, illegible to any except him for whom it was originally designed; and the art of thus secretly communicating intelligence has been generally termed _cryptography_. Many species of secret writing were known to the ancients. Sometimes a slave’s head was shaved, and the crown written upon with some indelible coloring fluid; after which the hair being permitted to grow again, information could be transmitted with little danger that discovery would ensue until the ambulatory epistle safely reached its destination. Cryptography, however, pure, properly embraces those modes of writing which are rendered legible only by means of some explanatory key which makes known the real signification of the ciphers employed to its possessor.” The key-phrase of this cryptograph is—“A word to the wise is sufficient.” The second is thus translated— “Nonsensical phrases and unmeaning combinations of words, as the learned lexicographer would have confessed himself, when hidden under cryptographic ciphers, serve to _perpdex_ the curious enquirer, and baffle penetration more completely than would the most profound _apothems_ of learned philosophers. Abstruse disquisitions of the scholiasts, were they but presented before him in the undisguised vocabulary of his mother tongue——” The last sentence here (as will be seen) is broken off short. The spelling we have strictly adhered to. _D_, by mistake, has been put for _l_ in _perplex_. The key-phrase is—“_Suaviter in modo, fortiter in re_.” In the ordinary cryptograph, as will be seen in reference to most of those we have specified above, the artificial alphabet agreed upon by the correspondents, is employed, letter for letter, in place of the usual or natural one. For example:—two parties wish to communicate secretly. It is arranged before parting that