Inversion

Inversion, in Music, is of three kinds. (1) Of a chord, when any other of its component notes than the root is placed lowest (see HARMONY). (2) Of an interval (within the octave), when the lower note is transposed an octave higher, or vice versa. To find what an interval becomes by inversion, subtract the figure denoting it from the figure nine; thus, a second inverted becomes a seventh, a third becomes a sixth, &c. In this change major intervals become minor, augmented intervals become diminished, and vice versa. (3) Of a subject or theme, when it is imitated in contrary motion—i.e. the melody progresses by the same intervals as the original theme, but ascends or descends always in a contrary direction. This is a frequent device in fugues and other contrapuntal music.