Nyctography

Nyctography is a substitution cipher script that Lewis Carroll, the pen name of Charles Lutwidge Dodgson, devised in 1891 so that he could write in complete darkness. He often woke at night with a thought he wanted to keep and did not want to light and then snuff out a lamp just to record it. The system pairs with a device he called the nyctograph, a card with a row of sixteen square holes, each a quarter inch wide, that guides the pen and keeps each character in its own box. Each letter is a small square figure built from dots at the corners and strokes along the sides, and every character carries a large dot in its upper left corner so that a reader can tell where one square begins. Besides the twenty six letters there are extra signs for and and the, and marker characters that announce figures, letters or a six digit date. Carroll wrote notes in the dark and transcribed them the next day. He first called the device a typhlograph, from the Greek word for blind, before settling on nyctograph, from the word for night.