Why Does a Pipe Organ Have a Pedal Keyboard?

The long row of keys beneath a pipe organ is not an enlarged set of pedals. It is a keyboard played by the feet. Pressing a pedal key may open pipes belonging to a dedicated bass stop, or use a coupler to draw on stops from a manual. Its central purpose is to give the feet a genuinely independent bass voice, leaving both hands free to continue with two or more upper parts.

The Metropolitan Museum of Art’s 1830 Appleton organ shows the structure clearly. It has two 58-note manuals, while a 27-note pedalboard was added when the instrument was reinstalled in 1883. The pedal division includes a 16-foot Subbass stop and can also be coupled separately to either manual. The example is also a useful warning against treating one arrangement as universal: pedal compass and independent bass resources varied across periods, regions and repertories.

In Bach’s organ counterpoint, the bass under the feet does more than make chord roots louder. It can sustain, walk, imitate a subject and converse clearly with the two hands. The difficulty is not merely hitting the correct pedal. Without looking down, the organist must judge distance, control note length and make the feet breathe within the same syntax as the hands. For a pianist, this reveals an important difference. Piano bass normally remains shaped by the hands; the organ divides the body into three independently organised systems of voices. What the pedalboard enlarges is not simply range, but the player’s contrapuntal agency.

Sources: https://www.metmuseum.org/art/collection/search/503670
https://www.metmuseum.org/fr/perspectives/appleton-organ-2