Poole appreciated "all musical
ratios derived from the
primes 3, 5, and 7" and more tentatively, 11, and he also asserted the melodic beauty of
microtonal commatic shifts. He described a 7-
limit double diatonic just scale to distinguish it from the usual
diatonic scale, which he called the
triple diatonic, with
common tones from
tonic,
dominant and
subdominant major triads. The new scale replaced subdominant pitches with the "perfect seventh and ninth of the dominant
harmony" to correspond better with what he heard harmonically and melodically in all kinds of music. Poole proposed using five parallel
chains of fifths from 1/1, 5/4, 25/16, 7/4 and 35/16, which he distinguished by
type and
case. One
octave needed 100 different
pitches to play in 19 different
keys.
triple diatonic (9/8) (10/9) (16/15) (9/8) (10/9) (9/8) (16/15) C D e F G a b C C D e (F7) G A b C (9/8) (10/9) (21/20) (8/7) (9/8) (10/9) (16/15)
double diatonic The 1849 organ was described being capable of playing eleven musical
(major) keys from the ordinary keyboard in
pure intonation by furnishing multiple pipes for each physical key, with foot pedals operating intermediate levers inserted into the tracker works to switch between pairs of pallet valves furnished for each note. The inventors described great benefits due to the tuning - they even claim it stayed in tune better - and argued how these balanced its greater size (up to 8 feet wider) and reduction in loudness compared with instruments of similar cost and number of pipes. They estimated one having "two Diapasons, the Trumpet, the Oboe, the Dulciana, the Flute and the Clarabella, in perfect tune" to cost between $4000 and $5000, and one third more if a Great Organ was desired. On the suggestion of
Thomas Perronet Thompson Poole developed a special keyboard to compel a "musician to know what he is doing", although A. U. Hayter, the King's Chapel organist, had complained about the care required by the existing plan. The new keyboard organized pitches in a similar fashion to an ordinary piano keyboard but also emphasized the different classes of pitches by using different shapes and colors of keytops. The 1/1 series was assigned to large white
natural keys arranged rising in diagonal rows, the 5/4 series on raised black
sharp keys between the white keys, the 7/4 series on square red keys followed by square yellow 63/32 and blue 45/32 keys behind the white keys (a 6/5 series could be added using buttons raised above the
sharp keys if desired). Key motion was linear and used two guide pins. The staggered keyboard arrangement separated distant key signatures and aligned octaves and was transpositionally invariant but not
generalized, although the abbreviated
pedalboard implied 3, 5, and 7 axes for 14 key-notes using three ranks of identical key levers. Poole outlined methods to increase the versatility of similarly arranged instruments, including a slightly tempered 78-tone scale, and a 106-tone scale with two cycles of
53 equal temperament (a
Bosanquet "multiple system"). On April 6, 1871 an enharmonic reed organ constructed by Joseph Alley using more uniformly shaped keys was demonstrated at a meeting of the Society of Arts in Boston by
Edward C. Pickering, and played by Edwin H. Higley. ==Publications==