An examination of a few Artrio-Angelus tracker bars shows that they
differ from one to the next in the elongations of the control ports, a
fact that is well known to technicians who have rebuilt Artrio-Angelus
instruments.

Early tracker bars made by Wilcox and White have symmetrical
elongations along the length of the roll for port positions 3 (loud
pedal) and 98 (soft pedal) and an asymmetrical elongation, in which only
the leading edge has been moved, for port position 1 (leaker).  There
may have been an earlier tracker bar yet that lacked the elongation for
the leaker, if we can trust the diagram of the tracker bar that appears
on page 7 of the undated booklet "The Artrio-Angelus Reproducing Piano
Instruction Book," published by Wilcox and White (later reprinted by
the Vestal Press).

Later tracker bars, both those manufactured by Wilcox and White and
those made by Simplex, have these same elongations, but in addition
have several others.  There is a symmetrical elongation for port
position 2 (rewind) and asymmetrical elongations, again with only
the leading edge moved, for port positions 0, 6, 7 (Accompaniment
intensities) and 92, 93, 96, 97, 99 (Solo intensities).  For both
early and late types of tracker bars the amount of elongation does
not seem to have been standardized.

The webbing cadences in Artrio-Angelus rolls reflect these differences
in tracker bar types, and there seem to be three different webbing
cadences in the rolls.  I call these early, late, and mixed.  The
early cadence, which appears in low-numbered rolls in the 7500 series,
uses a punch-skip-punch pattern for all ports except for ports 3 and
98, including the leaker.  This supports the idea that there was a very
early tracker bar for which the leaker port was not elongated.  An
example roll using this early cadence is 7525, Prelude Op. 3, No. 2
by Rachmaninoff, played by Harold Bauer.

The late cadence is used in higher-numbered rolls in the 7500 series
and 8000 series, and also all rolls in the 2000 series.  Here the
webbing pattern is punch-skip-skip-punch for all control ports,
regardless of their elongation.  For many late rolls there are few,
if any, lengthy control port perforations.  Port 0 (Accompaniment
intensity 3) is not used.  An example is 7970, Scherzo Op. 39 by
Chopin, played by Beryl Rubinstein.

The mixed cadence uses both punch-skip-punch and punch-skip-skip-punch
for the control ports, and adds a third cadence
(punch-skip-skip-skip-punch), which is used mostly for ports 6 and 7
(Accompaniment intensities 2 and 1).  An example is 7564, Sextette from
"Lucia di Lammermoor" by Donizetti, played by Ethel Leginska.

The existing technical literature for Artrio-Angelus is very sparse,
and as a consequence the reasons for the variations from one tracker
bar to the next, and for the differing webbing cadences, are unknown.
We can only guess what lead to this variety.  One person's guess is as
good as another's, but even so I will venture a guess of my own, with
the knowledge that it can never be either substantiated or disproved.

I surmise that the earliest tracker bars had symmetrical elongations
for the loud pedal and soft pedal ports only.  This required the use of
the "early" webbing pattern (punch-skip-punch) for the control ports.
In the earliest rolls the perforations for these ports are very long,
and as a consequence the paper is very weak and easily damaged, as we
can see from existing rolls.  To overcome this weakness, Wilcox and
White decided some time before 1919 (the date of the first rolls in the
2000 series) to add elongations to the other control ports.  These were
made asymmetrical to maintain compatibility of the new tracker bars
with existing rolls.

After introducing these elongations, all rolls were coded using the
"late" webbing pattern to strengthen the paper.  Unfortunately, these
rolls did not always play successfully on instruments using the earlier
tracker bar.

Finally, there was an event that called for updating the coding on the
early rolls.  This may have been the redesign of expression unit for
use with the Simplex pneumatic stack, or it may be that the Simplex
pneumatics (which are of the conventional "clamshell" type) differ so
much in their behavior from that of the Wilcox and White "pouch"
pneumatics that adjustments to the rolls became necessary.  In updating
the rolls, existing webbing cadences were left untouched but new
perforations used the new cadences, resulting in the "mixed" webbing
patterns.

If I am correct in guessing that rolls using the mixed webbing patterns
are updated versions of earlier rolls, we should find both versions of
rolls.  I have not yet encountered two versions of the same title with
different coding.

This is speculation, of course, and based on the examination of a
relatively small number of rolls.  I hope that as more Artrio-Angelus
rolls are scanned and made widely available we will be able to refine
our understanding of the various webbing cadences, and the reasons for
them.

I am happy to provide reconstructed punch matrices for the example
rolls mentioned above to anyone who is interested.

Wayne Stahnke