The holes Bob Fitterman has found in his orchestrion barrel are marks
for pinning barrels.  When a barrel was prepared for pinning it was
covered with paper most of the time.  Only new barrels were treated
blank.

The arrangement was made by slowly turning the barrel and by marking
the beginning and end of each note.  These marks were made by tapping
the corresponding key with a small hammer.  The (rectangular) tip of
the key then would leave a small slit in the wood and paper.  Bridges
were marked by pencil lines or other marks between the starting and
end marks.  After being marked the barrel was taken out and pins and
bridges were inserted according to the marks.  Special pliers were used
to bend the bridges into their proper shapes.

When a barrel had to be repinned all the old pins and bridges were
taken out.  To prevent confusion with the old marks the barrel was then
(re)covered with paper, and the procedure of marking was repeated.

I am pretty sure that Mr. Fitterman's barrel was indeed, as stated in
his theory #2, marked twice in the factory.  It may be possible to
recover the original songs on a newly-made barrel by copying the old
marks; it may be a time-consuming job, though.

Hans van Oost, KDV, Netherlands