Nyctography is a form of substitution cipher writing created by Lewis Carroll (Charles Lutwidge Dodgson) in 1891.
Nyctography is written with a nyctograph (also invented by Carroll) and uses a system of dots and strokes all based on a dot placed in the upper left corner. Using the Nyctograph, one could quickly jot down ideas or notes without the aid of light.
Carroll invented the Nyctograph and Nyctography because he was often awakened during the night with thoughts that needed to be written down immediately, and didn’t want to go through the lengthy process of lighting a lamp just to have to extinguish it shortly thereafter.
Each character had a large dot or circle in the upper-left corner.
Beside the 26 letters of the alphabet, there were five additional characters for ‘and’, ‘the’, the corners of the letter ‘f’ to indicate that the following characters were digits (‘figures’), the corners of the letter ‘l’ to indicate that they were letters, and the corners of the letter ‘d’ to indicate that the following six characters were a date in DDMMYY format.
There was no capitalization, punctuation or digits per se, though modern font designers have created them (e.g. capitals may be double-scored, punctuation marks may have the large dot at the bottom right corner, digits at the bottom left).
As in braille, letters were assigned to represent digits. The values were taken from his Memoria Technica, which assigned two consonants to each digit, with vowels unassigned, so that any number could be read off as a word. For nyctography, one of the consonants was used for each digit. Most are the initials of the numerals, as follows.
- 1 – b (first consonant)
- 2 – d (for duo and deux)
- 3 – t (for ‘three’)
- 4 – f (for ‘four’)
- 5 – l (roman numeral 50)
- 6 – s (for ‘six’)
- 7 – m (final of septem)
- 8 – h (for huit)
- 9 – n (for ‘nine’)
- 0 – z (for ‘zero’)