Clarification: Vicentino/Colonna 31 keyboards as "microtonal"

Hello, there, everyone, and having seen some comments come up in a
discussion of "31-note keyboards" in reference to the Bach era, I just
want to clarify that whatever might apply to the 18th century, the 31-note
meantone keyboards of Nicola Vicentino (1555) and Fabio Colonna (1618) are
definitely intended for enharmonic music using direct diesis or fifthtone
intervals. This would be "microtonal" by just about any 20th-century
definition.

Since "31-note keyboard" might for some people imply specifically a system
of 31-tET as formulated as Huygens near the end of the 17th century, I
would explain that my remarks here focus on an earlier 31-note tradition
based on a division of each whole-tone into five conceptually equal parts,
but quite possibly accomplished in practice using 1/4-comma meantone to
obtain a circulating (but not mathematically precisely equal or
closed) system.

In the 16th century, Vicentino was criticized by writers such as Vincenzo
Galilei for his use of the enharmonic diesis, an interval Galilei regards
as contrary to the "nature" of the human voice or ear.

Both Vicentino and Colonna give examples of music using these fifthtone
steps, and sometimes involving new types of vertical as well as melodic
intervals such Vicentino's "proximate minor third" or neutral third, for
which he gives an approximate ratio of 11:9, and finds rather consonant.

While Vicentino's keyboard could also be used for adaptive JI, his first
tuning in a cycle of 31 fifthtones is meant for enharmonic music -- read
"microtonal" in 20th-century terms. The revival of the Greek enharmonic
genus, with a semitone divided into two melodic steps, is a major theme of
his treatise, and of the examples of enharmonic music (including a
complete Latin setting in praise of his patron).

Colonna's keyboard is likewise intended for enharmonic music, with
examples of things like a "sliding of the voice" through sucessive
fifthtones. He divides the octave into 31 conceptually equal parts, and
makes no mention of any alternative adaptive JI tuning for the instrument,
unlike Vicentino.

Thus I would say that 31-note keyboards of the era 1550-1620 or so are
specifically intended for what would in later terms be called
"microtonal" music.

The intentions of a 31-note advocate like Huygens, closer to Bach's era,
may be another question; but I wanted to clarify that the 31-note
keyboards of the Manneristic era around 1540-1640 are intended
specifically for using intervals smaller than a semitone, and also
sometimes for new sonorities involving vertical intervals such as
Vicentino's "proximate minor" or neutral thirds.

Please forgive me if I misread any of the comments that suggested to me
this response, and again I would emphasize that my purpose here is to
explain the early "enharmonic" orientation of 31-note keyboards, not to
express an opinion on the viewpoints which may have prevailed by Bach's
era.

Most respectfully,

Margo Schulter
mschulter@value.net