polyphonic keyboard

Organistrum: new polyphonic keyboard

My reconstruction of the instrument is mainly based on my own interpretation of its possible musical function. Since I want to consider iit  as a genuine polyphonic instrument I  invented  a  special  keyboard, fit for 12th century two voices polyphonies, suggesting also a diffferent managing of the wheel.


By tuning the strings  either:  A – d – a   or:  A – e – a    we get an overall extension of two chromatic octaves (minus the last semitone). Before lifting each key, the performer  can choose which string he is going to touch, simply by turning the key to the proper position: the first one allows him to operate on the bass string, the second on the middle one, the third on the higher string.

Thus it is possible to play two different melodic lines simultaneously. In Santiago sculpture the hands of the musician on the right are on the third and on the fifth key. This means he is playing  -c, g -  rather than  -d, f -  bichord on bass and middle strings,  or  - g, c’  rather than  - f, d’- bichord on middle and higher strings (first tuning).


First string                              a..       a#      b     c’     c’#     d’

Middle string                         d..       d#      e      f      f#      g    

Bass string                            A..       A#      B     c     c#      d

Keys                                      0          1       2     3       4      5


 In position 4 the key is provided with two tangents so as to act on  second and  third strings (tuned either in Fifth or Fourth)  at the same time to perform  Organum parallelum, leaving the bass string as a drone. 

How they calculated the semitones progression

Known medieval texts neither describe  nor discuss about the possibility of a chromatic scale. But, reading Boethius's De institutione musica, easy to be found in monastic libraries since 9th century on, the monks could learn a lot about semitones both from pythagorean tradition and from Aristoxen's. There are only few lines, but enough, dedicated to the description of Aristoxen's practical method to divide the monochord. From this source the medieval scholar could learn a practical method in order to draw a correct chromatic scale of 12  tempered semitones. We discuss about this in another blog in this website


connecting astronomical and musical  knowledges through 10th and 12th centuries. Anyway, this idea comes from very early roman sources: Plinius and Boethius. In case the author of Santiago instrument intended to describe a revolutionary full chromatic/polyphonic keyboard we can suppose he was aware of that very ancient tradition.



On the other side, the musician who is in charge of turning the crank, by a smooth, even movement of his right hand,  can also lift one or even two of the strings from the edge of the wheel with his left hand in order to stop them vibrating. This way you can either avoid conflicts between the voices or stop  undesired drone effects.  








SYMPHONIA (CAELESTIS) should be preferred

- Reading Ch.Page articles in GSJ 1982, 83 convinced me to reject the name Organistrum

- Guido D'Arezzo Micrologus, XVIII, 1-18  pushed me to prefer the name Symphonia:

"...symphoniae, id est aptae vocum copulationes dicuntur, cum symphonia et de omni cantu dicatur." trad.: "...symphoniae are sound combinations, but this name indicates all songs"

Then, in Regulae rhythmicae the same author writes:

"Quinque habet ipsa tonos, duo semitonia;

Habet in se diapente et diatessaron;

maxima symphoniarum et vocum est unitas"


"(the diapason) contains 5 tones and 2 semitones/the fifth and the fourth/is the highest unity of symphoniae, or sounds"

SYMPHONIA matches with the medieval highest idea of music and sound, while ORGANISTRUM sounds like a deformation of the word ORGAN and like a ridiculous nickmame.

I believe that the name Organistrum  fits better the later "one-man Lyre", a diatonic, melodic instruments with drones, sort of early hurdygurdy used for secular music.

(Ch.Page is of the same opinion)



I chose one big  Red Willow (Salix purpurea) planck, seasoned in nature, from which I  carved the sound box and the base of the keyboard in one piece, average thickness  8-10 mm. Flat back, flat sides as in the original. 

GENERAL MEASURES:                      

 Total length    940mm                                                                                                           

Max width      230mm                                                                                                              

 Depth              80mm                                                                                                                

 Diapason        720mm


In the bottom of sound box I drilled a 10mm hole for the wooden axis, made of Beech (Fagus silvestris). Axis ends into another hole of 10mm drilled directly with no axle box in a wooden bar (Spruce) 15mm thick, glued between the two lobes of sound box which has been carved out of one piece of Spruce (Picea  abies) 8mm thick with no other bars glued underneath. Keyboard  box is independent from the body of the instrument and can be easily removed to modify  general level of the bars, changing their angle with the strings or making reparations. The 11 bars of the keys, diameter 10mm, are of Pine (Pinus nigra) and the 55 pivoting tangents of Beech. The problem of the distances among the bars is discussed in the present article. To avoid noise made by the bars returning to their previous position, after being pulled up to play, a stripe of cloth has been glued at the bottom of the keyboard. The carved lid has been made of Spruce, 8mm thick and is simply interlocked with the body of the keyboard without any hinge or other device.

The wheel, 11cm  wide and 20mm thick is of Walnut (Juglans regia) and forced on  wooden axis without any screw, nail, or wedge. No axle box at the end. The Beech crank , stuck in the square end of the axis, can be easily removed. The soundboard is glued to the body of the instrument , no sound pole in it. The bridge is of Poplar (Populus nigra) reinforced with a Beech edge. The tailpiece  of Chestnut (Castanea sativa) is linked to the bottom of sound box by a leather lace. Tuning pegs are of Beech, no need for a tuning key. Two light  layers of pure almond oil have  been used as  finishing . Gut strings: 0.80, 1.10, 1.40mm.






Congrés du CTHS, Paris 23-27 avril 2018

Congrés du CTHS, Paris 23-27 avril 2018


“Livres en pierre” est une denomination donnée de très longtemps aux portails des églises  romanes et gothiques. La doctrine catholique y était très clairement exposée à travers la présentation des scènes bibliques, voilà donc  une effective transmission de connaissances théologiques. Mais d’autres savoirs pouvaient etre tout aussi transmis: histoire, astronomie, musique. Parfois , au moyen d’un language codé, on exposait des connaissances secrètes.

Nous avons étudié trois exemples excéllentes: les portails  des cathédrales de Chartres,  Arles  et Saint Jacques de Compostelle, en mettant en évidence une transmission de connaissances de musique et d’astronomie. On voit que les sculpteurs ont représenté avec le plus grand souci les instruments de musique, leur tenue, les détails de fabrication, les decorations et meme les figures des musiciens, des chanteurs, des anges, leur expression, leur attitude. Le nombre, la position des sujets, les endroits occupés dans la composition, les relations entre les personnages, tous ces eléments donnent indications et suggestions au regard  des études de théorie musicale conduits à l’époque (1143-1188): numérologie musicale à Chartres, intervalles de l’exachorde à Arles, Musica mundana avec références à la cosmologie platonicienne et à l’astronomie et gamme chromatique à Saint Jacques de Compostelle  .

Dans le portail Royal de Chartres plusieurs instruments de musique sont representés. Les deux “Psalterions decacordes” on étés mis bien en evidence, l’un sur les genoux de “la Musique”, l’autre dans la main d’un des veillards de l’Apocalypse, mais pourquoi présentent-ils seulement 9 choeurs ?

Dans l’archivolte de Saint Trophime on voit que les anges sont disposés sur un sorte de pentagramme, la position de leur tetes indiquant les notes musicales, tandis que les chiffres qu’on découvre en analyzant les figures, mises en relation, donnent les fractions correspondantes aux intervalles entre ces notes.

Enfin, dans le portail de Saint Jacques de Compostelle, on voit les 24 veillards de l’Apocalypse qui portent des differents instruments à cordes. Les deux au centre tiennent leur instrument sur les genoux: le premier tourne une manivelle, l’autre actionne des touches. On voit 11 touches dans l’octave, plus le sillet, donc la gamme de l’instrument est certainement chromatique. Mais pourquoi faire un instrument chromatique si l’on n’employait à l’époque que des gammes diatoniques, sourtout dans la musique sacrée? On analyse la structure et les decorations de l’instrument sculpté et on découvre des notions de cosmologie, d’astronomie et de théorie musicale.


La transmission des savoirs musicales à travers les sculptures des portails des églises était importante, car la Musique (des Sphères), liée à l’Astronomie, était considerée comme un moyen de communication avec Dieu. Quelques détails pouvaient etre compris uniquement par un public savant.


AAVV, El mensaje simbòlico del imaginario romànico. Aguilar de Campoo, Fundacion santa Maria la Real, 2012

Elena Ferrari Barassi, Testimonianze organologiche nelle fonti teoriche dei secoli X-XIV.  Cremona, Fondazione Claudio Monteverdi, 1983

Boethius Severinus Manlius Torquatus, De institutione musice.

Bruce Eastwood, Ordering the Heavens. Brill, 2007

Dieu Lionel, La Musique dans la sculpture romane en France, Centre de Développement en Art et Culture Médiévale, 2006



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