We have already seen that this new compound chord, the chromatic, like the dominant seventh and subdominant sixth, is a 4-note chord, and, like them, made up of minor thirds - they mostly so, this wholly so; and we have seen that this compound chord embraces the whole octave, cutting it into minor thirds -

And now we shall also see the chromatic chord system cutting the octave into semitones. If we follow this chromatic chord system out, we shall have the octave [Scientific Basis and Build of Music, page 55]