I think I have a good understanding of how the editors at Aeolian
used the standard resources of their organs to perform the fully
automatic Duo Art rolls.  Still, there are a few mysteries.

Many larger installations included the first "Surround Sound" of
recorded music.  With main chambers at the front of the room and
the Echo organ at some distance in the rear, Aeolian also include
antiphonal chambers in the side walls.  If these organs were
equipped with Duo Art players, all these resources could be used.
The question is how?

The switching device that turns the stops on and off is called
a "jack box".  This unit also couples the chimes and harp to either
the great or swell manuals.  The Echo organ is coupled in similar
fashion.  When the jack box couples the Echo to the swell manual,
eight contacts are closed.  Why eight?  Most stops and other
couplers have four contacts on the jack box.

Taken from the printed instructions on the early Duo Art rolls, it
appears that the standard Echo organ calls for three stops.  They
are Vox Humana, Soft Flute, and String PP and Echo Tremolo.  So does
the jack box always activate these stops with those eight contacts,
or could these stops become active from the Swell stops of similar
character?

Those Swell stops do have four contacts on the jack box.  If the
latter is the case, the Echo organ could have some variation in its
stop selection rather than being hard wired to only have those three
stops mentioned above.

And what about those Antiphonal chambers at the sides of the room.
Some of them had twelve ranks or more.  Yes, there is the "Tonal" jack
box switch that turns on just about everything, but certainly there
must have been additional schemes to control these other attributes.

The jack box control is found on all Duo Art organs and it never
seems to vary in size, yet the organ may have from eight to over one
hundred ranks.  The jack box has twenty-six specific rank switches,
plus couplers.

The best answers to my questions lie in tracing the wiring on large
original installations.  Aeolian did not waste the resources of the
huge organs they installed.  It is obvious from the rolls that they
wanted their patrons to feel the power of the organ that they paid
dearly for.  Society organist Archer Gibson, with 75 rolls to his
credit, delivered that power to many patrons both in person and by
roll.  He knew how to keep them happy.

So few original large installations remain, that the information
I seek is elusive.  Has anyone traced the wiring of a large Aeolian?

Bob Taylor