Enharmonic

Enharmonic, originally the name of one of the three Greek scales, is now applied to music constructed on a scale containing intervals less than a semitone—e.g. where the difference is recognised between G$\backslash sharp$ and A$\backslash flat$, or D$\backslash sharp$ and E$\backslash flat$. On the old organ built by 'Father' Smith for the Temple Church in London these notes had separate keys. But in modern keyed instruments, tuned, as they now universally are, in equal temperament, these notes are represented by the same sound; and the possibility is afforded of enharmonic modulation, in which a chord belonging to one key is, by a change merely of its notation, made the means of passing into another key. The chords commonly used in this change are the diminished seventh, or equivocal chord, which may be written in four different ways, and (less frequently) the dominant seventh, which may be changed into the German sixth. See MUSIC.