As before, this note is intended primarily for Spencer Chase, but it is
provided through the Digest for the benefit of other subscribers with an
interest in the subject.

Spencer, the editor of the Digest pointed out that I had not in fact
answered the question you posed.  This note is an attempt to make amends,
and give you what you asked for in a direct manner.

     (1) The punch advance of "coarse" Duo-Art rolls corresponds to 253
punch steps per foot.  This number is a surprise, since 256 punch steps
per foot corresponds to 3/64 inch punch advance.  (A fractional-inch
advance would have been a natural choice for machinery designed and built
in the United States in the early part of this century.)

     (2) The number given above was determined by counting punch steps in
the master roll for the 1921 Electric Duo-Art Tester, the standard test
roll used throughout the early and mid 1920s.  (This roll was replaced in
1927 by the New Duo-Art Test Roll No. 3.)  There are 11 foot markers in
all, with displacements of 0,1,2,3,4,5,6,7,8,9,10 feet from the start of
the Tempo Test, as identified by the printed annotations on the roll.
These markers are perforated into the roll as two adjacent speaking notes,
and occur in rows 0, 253, 506,759,1012,1265,1518,1771,2024,2277,2530.

     (3) The punch advance was changed sometime in the mid 1920s.  The
new "fine" punch advance is very nearly 2/3 times the old one.  Its
exact value is not known.

    (4) You can determine the ratio of "coarse" to "fine" advances by
examining the Duo-Art perforators, which still exist.  The change was
effected on the factory floor by moving a pawl so that it engaged one or
the other of two rachets, one for "fine" and one for "coarse."  The ratio
can be found by simply counting the number of teeth on the ratchets.
The perforators can be located through Robin Pratt, the publisher of the
Amica Bulletin, who knows of their whereabouts.  Robin is a subscriber
to this Digest.

     (5) I sincerely hope you will go to the trouble of locating and
examining the Duo-Art perforators and solving this riddle for all of us
once and for all.  I (for one) can make use of the information to improve
my roll translations.  There are others who would also be grateful for
your contribution.

     (6) Starting in the early 1930s, Ampico popular rolls were perforated
on the Duo-Art perforators and therefore use either "coarse" or "fine"
Duo-Art punch advance.  Thus, a complete understanding of the Duo-Art
machinery also solves the question of the punch advance used for Ampico
popular music of the '30s.

I hope this note is more to the point than my earlier one.  With best
regards, I remain

Sincerely Yours,

Wayne Stahnke¶
Live Performance