THE SECRET CODE BOOK

A pithy compendium of secret codes for everyone who ever imagined being a spy or simply communicating in secret. Huckle reaches back over the centuries to discuss the codes that were used to send secret messages. Beginning with the communiques sent by the Spartan army in the fifth century b.c. and deciphered with a device called a ``skytale,'' the book covers everything from signals sent by flags, flashing lights, within innocuous-sounding correspondence, hieroglyphs, Morse code, Jefferson's cipher wheel, the WW II Enigma machine, etc. The book instructs readers how to encode their words as well as how to decipher or decode messages sent by others. Of course, the punch- out cipher disks and grille shouldn't be expected to last many rounds of institutional use, but the clear, comprehensible information means that even if those devices fall into the wrong hands, code-breakers and le CarrÇ wannabes will have much to ponder and use. (Nonfiction. 8+)