First, my thanks to Gérard Dabonot for his comments on the 27/29-note
French scales [240421 MMD]. While my high school French from 70 years
ago works well for wonderful holidays in France, it has so far been
too limited to let me follow the orgue de Barbarie world on the web.

The link to Gérard's website helped me find some very interesting
information, including offerings of books and rolls. There is a great
assortment available, but the music books appear to cost about three
times as much as "our" paper rolls. The 27/29 scale is good. With MIDI,
I suspect that a simple interchange between 27/29-note and 31-note
arrangements is probably practical, but I haven't done a note-by-note
comparison.

The point I intended was that a 27/29 scale book playing instrument is
probably a poor choice for a novice builder who wants to play American
or British or German music.

Furthermore, while the plans package which brought this issue
forward is in English, attractively presented, apparently easy to 
follow, and_Free!_, I doubt that a novice can actually complete 
a build. The construction becomes increasingly complex as you progress.

I do not have a good knowledge of French plans, but I expect that there
are far better ones for a novice builder available at a fair price.
It would be valuable to have a list of, or links to, such plans made
available to the English speaking world.

A recent post on the Busker Organ Forum was from an individual who had
started to build from the plans, and was requesting advice on how to
convert the 27/29 carton (book) tracker bar to play 20 or 31 note rolls.
That's what drew the advice to switch to the popular and well supported
"English" designs.

Wallace Venable