Charles Dodgson (pen name Lewis Carroll) had difficulty remembering numbers, such as dates. He developed a cipher to help him remember numbers by embedding them in couplets or phrases. For example, the couplet “Brass trumpet and brazen bassoon, will speedily mark you a tune” encodes the specific gravity of brass (8.39) in the last four consonants: r k t n (y is treated as a vowel). In this article, we describe the cipher, present online tools for encoding and decoding, discuss how we impl...
