Split Key soup (was re: Amateur question)

Hi - sorry for my delayed response, I've made a giant mess here in my
shop!

Split-key arrangements can be fairly efficient devices to permit larger
sets of simultaneously available notes in a keyboard. As Judith points
out, they're traditional and if only sharps are split these fill the
same depth and breadth as a Halberstadt-style chromatic keyboard yet
without disturbing the visual/tactile arrangement. The height of the
additional keys is a function of the dip required by an instrument -
keys that 'bury' are annoying (a serious handicap to sharps split across
their widths, for instance as extrapolated by Jack Peters from a Zarlino
print in a tiny 19-tone instrument: <http://jackpeters.com/>).

I think, for the most part, antique split key arrangements were not
intended to close tunings, but rather to remove wolves a little further
from common practice. One late example, a 1766 square piano by Zumpe
(Harding, "The Piano-Forte" p69) appears to permit 17 tones per octave,
but closer inspection shows several dummy keys at either end of the
compass. This would concur with the practice of short octaves*
originally which omitted accidentals (Marcuse, "A Survey of Musical
Instruments" p236).

* A friend related a story that a harpsichordist visiting his shop said
something like "Short octave - why, if anything this keyboard has wider
octaves than normal!"

If the elegance of split sharps is their minimal intrusion, split
naturals are a little messy depending on the extent and manner of their
integration. Nested between sharps they're always buried and their
reduction in width requires more precision of a player (and builder!).
Placed before naturals, the depth of the keyboard may be increased - the
same as for what seems the most common approach, in setting them behind
the chromatic keyboard, nearly as separate manuals (which, in the case
of the Sambuca lincea, they kind of are [Martin, "The Colonna-Stella
Samuca lincea" JAMIS v.10, p5-21]).

Additional notes present mechanical challenges whatever device is used
to introduce them. I built (it says 1999 on the name board but still
it's not finished...) an obliquely-strung virginal because the stringing
scheme permits strike (pluck) bands to be wider than might offset
keyplank back-scales, and shared jack-slots don't alter plucking
lengths. Its crazy keyboard has 22-tones per octave throughout its
3-octaves and a fourth compass, with a normal, ~165mm octave span, split
sharps, and split C's, E's, F's, G's, and B's. This is playable, if not
exactly comfortable - the instrument has other problems as well, so I
hope it's just an early attempt...

Harding reports a root-controller piano invented by Clagget in 1788
called the Telio-chordon: "Every octave could be divided into
thirty-nine gradations of sound and any key could be made to sound one
of these degrees of intonation. In order to produce these variations he
added two extra bridges placed nearer to the hammers," between(? she
writes above) which were placed bars that could be lowered by means of
pedals to engage the alternate speaking lengths. (Clagget and Dr. K.
Chr. Fr. Krause each had keyboards with keys identically-shaped and all
in the same plane, the latter without color cues)

Eivind Groven designed two related instruments, one an organ still in
use in Oslo, the other an unfinished piano which made use of switching
arrays to select between 36 (JI) tones from three separate instruments.
David Loberg Code continues this work using MIDI-equipped,
solenoid-driven player pianos <http://eeyore.cc.wmich.edu/~code/groven/>
(The same, or a similar system was used to perform Antheil's "Ballet
Mechanique" with a mass of pianos).

While these devices are limited only to 12 simultaneously available
notes, Yamaha proposes in US Patent no. 5516981 a 19-tone keyboard
through logic which can switch between 12- and 19tET (from John
Chalmers' links page at
<http://www.ixpres.com/interval/chalmers/links.htm>).

A microtonal Rhodes would be super, but where to get parts?

Clark