As Oscar Stern asked (and since he asked me personally a week ago or so
and I didn't find time for an answer yet) I took out some old pictures
of the Seybold Magic Organa (the only Magic Organa I own), which has air
hoses to supply the 3 rhythm instruments (drum, snare drum, high hat).

I also have the tester gamma (scale) roll for this instrument, but even
that doesn't answer Oscar's question because the notes are not marked
on the roll.

But anyway, as I began to have a look on my pictures again, I may
contribute a little to the background of the Magic Organa and will do
so on MMD. Maybe some other readers are interested in the subject also.

Picture 01 shows an enlarged view of the tracker bar and, as one can
easily count, it has 44 holes.

Picture 02 shows the valves on the treble side of the instrument which
accounts for 20 of the notes, as we easily can see by counting the
valves.

Picture 03 shows all of the hoses which are led through the hose-package
in the bellows to the treble side. As one may notice there are 10 hoses
on the left side of the picture but 13 on the right side. The upper four
shown are responsible for the rhythm section, as a best guess the snare
drum needs two valves for fast repeating.

In picture 04, as one can also see easily by counting the valves, we
have 9 valves on the upper side and 10 on the lower one. That sums up
to a total of 39 playable notes and 4 holes on the tracker bar for the
drum set, i.e., 43 used holes on the bar.

There is 1 unused hole left on the bar we have to deal with and
I think I have an explanation for that. The tracker bar was also used
in other Seybold instruments that consist of accordion and drum set but
those were made to play automatically. So the hole remaining must have
been responsible for automatic rewind and to shut down the rewind
process.

All photos may be used freely because they were made by the author.
Kind regards to all users of MMD!

Uwe Gernert
Germany

 [   01. Tracker bar
 [ https://www.mmdigest.com/Attachments/21/11/28/211128_045427_01_trackerbar_enlarged.JPG 
 [   02. Valves on treble side
 [ https://www.mmdigest.com/Attachments/21/11/28/211128_045427_02_treble_side.JPG 
 [   03. Hoses on treble side
 [ https://www.mmdigest.com/Attachments/21/11/28/211128_045427_03_treble_side..JPG 
 [   04. Valves on bass side
 [ https://www.mmdigest.com/Attachments/21/11/28/211128_045427_04_bass_side.JPG