The Compositional Basis

This music (cerdd dant) was composed according to a binary system in which the eight notes or strings of the octave were divided into two sets: principal and weak, prinsipal a gwan. A typical division might be:

, C, D, G (principal)

A,.Bb, Eb, F (weak)

corresponding closely to Boethius’ ‘fixed’ and ‘movable’ strings (De institutione musica, written before 510 A.D.) and the ‘hestotes‘ and ‘kinoumenoi’ of the ancient Greeks. The principal or fixed set is identified with the Pythagorean ratio – 12 : 9 : 8 : 6. Applied to the division of the monochord, this ratio gives rise to the octave, fifth, fourth and the wide, Pythagorean tone.

In cerdd dant a stave or line of music is divided into equal periods of time and each period is assigned either to the cyweirdannau (‘I’s) or tyniadau (‘O’s) the latter are usually made from the the lleddfdannau. A mesur or measure is one of the conventional binary patterns, The Twenty four Measures of String Music, Y Pedwar Mesur ar Hugain Cerdd Dant, the simplest of which is Tytyr Bach OOII OOII, the longest is Mak y Mwn Hir IIII OOOO IOIO IIII OOOO IOII. Sometimes the completion of a mesur once through is called a kaingk, in some cases shorter mesurau like Tytyr Bach should be repeated to make a kaingk.

Page 107, Robert ap Huw manuscript, transcribed by Robert Evans

llyma / r / pedwar mesur arhigain kerdd dant

Here are the twenty four measures of string music.

mak y mwn hir		IIII OOOO IOIO IIII OOOO IOII
korffiniwr		IIOOIOII . IIOOIOII
korsgoleff		IIOIIOOIOII
Rhiniart		IOOI.IOOII [sic] [recte.IOOII.IOOII]
koraldan		IIIOIOOIOOOI
tresi heli		IOOOIIIOOOIOII
wnsach		IIIIOOOI
kor dia tutlach		IOIIOOOIIOOIIII
korfinfaen		IOIIOII . IOIIOII
korwrgog		IOOIOIIOII
karsi		IOOOIOII . IOOOIOII
brath yn ysgol		IOIIOIOOIOIIOIOOIOII
fflamgwr gwran		IOII . IOIIOOIIOOII
mak y mwn byrr		IIOOIIII
kalchan		IIOOIIIIOI
bryt odidog		OOIO : OOIO : IIOI : IIOI
trwsgwl mawr		OOOOIIIIOOOOIOII
tytyr bach		OOIIOOII
mak y mynfaen		OO)IIOO : OOIIOOIIII
toddf		OIIOOOII
hatyr		OOIOII . OOIOII
mak y delgi		OIIIOII
alban hyfaidd		IOII . OIOO . OIOO . IOII
alfarch		OOOOOOOO IIIIIIII

Terfyn y pedwar mesur arhigain kerdd dant.

End of the twenty four measures of string music.

Page 107, Robert ap Huw MS, showing the names of the mesurau or measures and the mesurau in binary notation.

During a ‘I‘ the cyweirdannau are predominant and during an ‘O‘ or tyniad, the lleddfdannau are predominant. Generally the ‘I‘s and ‘O‘s are easy to discern in the bass part of the tablature. In the treble especially, notes or strings from the non-predominant set are recruited to make musical figuration. The bass is generally more stable than the treble. The figuration is not mere ornamentation. There are four main categories of figure each with one or more rhetorical functions.

Plethiadau,	in English, ‘plaitings’ or ‘weavings’, these may begin a cyweirdant (‘I‘) or tyniad (‘O‘), may beautify between a ‘I‘ or an ‘O‘ and cause contention, each with the other.
Tagiadau,	‘chokings’, these are stops or rests between ‘I‘s and ‘O‘s.
Cysylltiadau,	‘joinings’ or ‘connections’, these join ‘I‘s and ‘O‘s.
Crychiadau,	‘wrinklings’ or ‘ripples’ (tremulando effects), these complete or perfect ‘I’s and ‘O‘s or come between ‘I‘s and ‘O‘s.

Detail of p. 35, Robert ap Huw MS, showing part of the key for reading the tablature. The names of the figures are written first, then the figures are represented as columns of letters with different signs above them, as they appear in the tablature. The fingering and damping for each figure is shown in triangular notation on a stave. Robert ap Huw has used the free space at the end of the line to write a fingering chart for the lower hand.

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