History of Turn the Rings
Rings with signs that are turned against each other are old: Leon Battista Alberti described a cipher disk of two turning rings in 1467. The puzzle here is made for PaperGames.
Alberti's cipher disk
In 1467 the Italian scholar Leon Battista Alberti described, in his treatise on ciphers, a disk of two rings joined by a pin: a fixed outer ring with letters and a turning inner ring with other signs. Turning the inner ring paired each letter with a different sign. It is counted as the first example of a cipher with several alphabets.
Rings as a puzzle
Puzzles in which rings or disks with pictures are turned until everything lines up are found today in many forms, as toys and in puzzle books. The version here - with up to five rings and, on Hard, rings that turn their neighbour along - is made for PaperGames. The computer checks every puzzle and counts its fewest moves.