""A Treatise On The Art Of Deciphering, And Of Writing In Cypher: With An Harmonic Alphabet"" is a book written by Philip Thicknesse and published in 1772. The book is a comprehensive guide on the art of deciphering and writing in cypher, with a focus on the use of an innovative harmonic alphabet. The author provides detailed instructions and examples on how to create and use various types of ciphers, including substitution ciphers, transposition ciphers, and polyalphabetic ciphers. The book also covers the history of cryptography, including famous examples of codes and ciphers used throughout history. Overall, ""A Treatise On The Art Of Deciphering, And Of Writing In Cypher: With An Harmonic Alphabet"" is a valuable resource for anyone interested in the art of cryptography and the history of codes and ciphers.This scarce antiquarian book is a facsimile reprint of the old original and may contain some imperfections such as library marks and notations. Because we believe this work is culturally important, we have made it available as part of our commitment for protecting, preserving, and promoting the world's literature in affordable, high quality, modern editions, that are true to their original work.