Tool for translating the Chappe alphabet (encryption/coding and decryption/decoding mode) used by the aerial/optical telegraph.
Chappe Alphabet - dCode
Tag(s) : Symbol Substitution
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The aerial telegraph proposed by Claude Chappe uses by default a series of numbered positions: the Chappe code (associated with a vocabulary). However, several sources seem to indicate additional positions/signals/semaphores which would have been used to spell a word or a name absent from the vocabulary, these positions represent the Chappe alphabet.
The Chappe alphabet associates each letter with a position of the Chappe tower according to the table:
Note the absence of the J and the presence of the & symbol. Also, some sources indicate that the 0 directly encodes the value 10.
The Chappe's alphabet is made up of visual signals similar in all respects to the Chappe code (but the positions are different).
It is likely that other alphabets and letter combinations were used.
Moreover, doubts remain as to the veracity of this alphabet. Its content (25 letters, 10 numbers and 1 symbol) is surprising, given the number of possible positions, the lack of correspondence for the J is surprising.
dCode uses the font made by Keiichiro @9SQ on Github here (link)
The Chappe telegraph was presented in 1793, the Chappe code and therefore the Chappe alphabet probably date from this period.
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Cite as source (bibliography):
Chappe Alphabet on dCode.fr [online website], retrieved on 2022-08-08,