In addition to tone color, the harmonic series functions in organ registration in another way:
In choosing stop combinations, the harmonic series serves as a logical guideline or reference point. In choosing 8', 4', 2 2/3', and 2' stops, for example, you are in a way constructing your own harmonic series. By leaving out certain stops (for example, skipping the 4' and 2 2/3', leaving only 8' and 2'), you are eliminating those partials and creating a distinctive tone color (an 8' and 2' combination creates a lighter, hollow sound).