History of the Greek alphabet retained the sound. A symbol based on the left-hand half ( ├ ) of the letter Η was therefore sometimes used to indicate the presence of where necessary, and its absence was indicated by a symbol based on the right half. During the classical period, ΕΙ came to be pronounced and ΟΥ came to be pronounced , Υ having meanwhile moved to . By about 200 BC, a system of diacritical marks was invented, representing the tone accents in use in Ancient Greek. This also helped to indicate the length of the vowels Α, Ι, and Υ in certain cases
The Alphabet Cipher this table is lost, it can easily be written out from memory, by observing that the first symbol in each column is the same as the letter naming the column, and that they are continued downwards in alphabetical order. It would only be necessary to write out the particular columns required by the key-word, but such a paper would afford an adversary the means for discovering the key-word. For a working demonstration tool for the Alphabet Cipher visit lewiscarrollresources.net The Alphabet Cipher Lewis Carroll published "The Alphabet-Cipher" in 1868, possibly in a children's magazine. It describes what is known as