Thank you to all who have been contributing to my quest for information.
Here's an update.

Okay, I've found another clue: On the reverse of the crank handle is
stamped "PROSPER".  Assuming that's a proper name, does it mean anything
to anyone?  (It's in the same stamped font as the "MEDAILLE 1= CLASSE"
found on the organ, so the crank is original.)

The front bottom veneer (rose) is not original (having been placed over
a couple of original screw holes.)

The second 17-note rank is on a register slide.  Since the majority of
the second rank appeared to be slightly flat of unison, I assumed that
they're intended to be a celeste, with the exception of the low C, G
and B which are octaves.  (I put the octaves in unison.)  But Hans van
Oost suggested in 050915 MMDigest that they should be unison, and
that would be good, too.  The jury's still out.

Scale is C G B C D E F F# G A B C D E F F# G A B C D E.
The second rank consists of octaves of C, G and B, and unison (or
celeste) of the high fourteen notes G through E.

Oh, and I should mention that I can't count.  It was 22-notes, 39
pipes.  Regardless of whatever I said in my original post. <face red>

Thanks, and please continue any comments/information you may have!

Todd Augsburger - Roller Organs
http://www.rollerorgans.com/