Orwell comma

In musical tuning, the Orwell comma is a very small musical interval of 13.07 cents and frequency ratio of 1728:1715 or 26·33 : 5·73. It can be thought of as the difference between three just septimal minor thirds and one just minor sixth. It is so named because the temperament eliminating this comma, Orwell temperament, has an optimal generator very close to 19 steps out of 84-equal temperament; this pattern of 19/84 (or 19\84 ) steps is similar to the title of Orwell's novel 1984.