24. _Chromatic_ notes and chords are those which do not belong to the
diatonic scale of the passage in which they occur, but which are not
so used as to cause modulation.
25. _Enharmonic_ intervals are minute intervals which never occur in
music as directly measured quantities, though they exist as
differences between approximately equal ordinary intervals, diatonic
or chromatic. In an enharmonic modulation, two chords differing by an
enharmonic quantity are treated as identical.
26. _Pedal_ or _organ point_ is the sustaining of a single note in the
bass (or, in the case of an _inverted pedal_, in an upper part) while
the harmonies move independently. Unless the harmonies are sometimes
foreign to the sustained note, it does not constitute a pedal. In
modern music pedals take place on either the tonic or the dominant,
other pedal-notes being rare and of complex meaning. Double pedals (of
tonic and dominant, with tonic below) are not unusual. The device is
capable of very free treatment, and has produced many very bold and
rich harmonic effects in music since the earlier works of Beethoven.
It probably accounts for many so-called "essential discords."
In the form of _drones_ the pedal is the only real harmonic device of
ancient and primitive music. The ancient Greeks sometimes used a
reiterated instrumental note as an accompaniment _above_ the melody.
These primitive devices, though harmonic in the true modern sense of
the word, are out of the line of harmonic development, and did not
help it in any definite way.
27. The _fundamental bass_ of a harmonic passage is an imaginary bass
consisting of the roots of the chords.
28. A _figured bass_, or _continuo_, is the bass of a composition
supplied with numerals indicating the chords to be filled in by the
accompanist. _Thorough-bass_ (Ger. _Generalbass_) is the art of
interpreting such figures. (D. F. T.)