An Echo Organ (or division) is a small set of organ pipes, typically
three to five ranks, which is located at some distance from the main
organ.   Its function is to imitate a distant echo, as from a far away
location.   It is used alone.  On my 33-rank Aeolian the three ranks on
the Echo chest are: Vox Humana, soft strings, and soft flute.

The sort of effect that can be produced is, for example, on the roll
"The Death of Mimi" from "La Boheme."  After a sort of reverie, where
we hear resumes of tunes that have portrayed characters and events of
her life, the chimes sound -- we assume she has died -- and the last
few chords are played on the Echo Organ, as if from heaven.  It is very
moving.

Paul Morris