At the back of the Great/Choir enclosure is the harp. The
tuned metal bars are mounted over resonators that extend as much as two feet
behind the bars. Each bar is struck with a felt tipped beater and the
tone produced is quite mellow. Aeolian installed this style of harp
in almost all of its organs. The rolls use the harp extensively. It
is sometimes used as a solo instrument, but often is used as an accompaniment
with the pipes. The tone blends very well with flutes and diapason ranks
The harp has 49 notes, but is wired to play from all 61 keys. This arrangement is called "augmented" in Aeolian parlance. The mechanism is overly complex. Each note has in addition to a beater, a return pneumatic pouch, and a damper that pneumatically retracts from each bar when it is played. A mechanism that limits the blow of the beaters is also used. It is similar to the "half blow" or hammer rail lift found in pianos. The volume output is substantially reduced when the mechanism is active. While complex, it is capable of rapid response and its contribution to the music is wonderful.
Partially installed pipes in front of the harp show just how compact Aeolian made their chests. This first rank shown is Flauto Dolce pipes and adjacent pipes almost touch.
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