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MIXTURES AND MUTATIONS

Mr. HENRY WILLIS

This subject is one of outstanding interest to us for Mixtures and Mutations belong to the Organ and no other musical instrument.
As is well known, the Organs of 1,000 years ago and for some time later, were one big mixture-based upon the harmonic series:-
e.g. 11, 8, 12, 15, 17, 19, 22.
The first separation of the upper work from the foundation stops that can be traced was at Halberstadt Cathedral in 1361, and it is from that date that development took place with rapidity and mixtures became the crowning glory of the flue work.
Let us consider the many different names given to mixtures, mostly indicative-of the type and composition:--
Mixture, Sesquialtera, Furniture, Cornet, Plein-Jeu, Scharf, Scherp, Acuta, Cymbel, Glockenspiel, Carillon, and the Italian and Spanish generic terms-Ripieno and Lleno respectively.
Perhaps the most happy generic term for the Mixture is the Italian Ripieno meaning "filling in" for this describes the true function of a mixture to perfection.
The normal use of unison ranks ceasing at the Fifteenth, the requirements of adequate accompaniment and lead to massed voices - as instanced in the lusty singing in German Churches in the latter middle ages - necessitated the development of the mixture to that end.
In the old days of short manual compass, the 17 rank could be taken throughout the compass - but the addition of 19, 22, 24, 26, 29 and higher ranks rendered "breaks" essential - these breaks were at first carried out by breaking back all ranks together at appropriate points and the earlier German Mixtures broke back at the octaves: indeed, these mixtures were as Cymbels in which every rank breaks back every octave. An example is given of a typical German design of the 17th century-a Furniture and Cymbel each of three ranks superimposed when an already adequate flue chorus complete, with mutations, to the 15th or super-octave.
Furniture:-1-12. 19, 22, 26, G.C.G.
13-24. 15, 19, 22. C.G.C.
25-36. 8, 12, 15. C.G.C.
37 - 49.1, 8, C.C.G.
Cymbel.-1-12. 29, 33, 36.
13-24. 22, 26, 29.
25-36. 15, 19, 22.
37-43. 12, 15, 19. strictly speaking should he
43- 8, 12, 15.8, 12, 15.
1, 5, 8.

The excellent internetting of the two will he readily observed and, combined, the ranks read as follows:-
1 - 12.19, 22, 26, 29, 33, 36.
13 - 24.15, 19, 22, 22, 26, 29.
25 - 36.81 12, 15, 15, 19, 22.
33 - 43.1, 8, 12, 12, 15, 19.
43 - 49.1, 8, 8, 12, 12, 15.

In the above, the doubling of the unison in the first and second breaks, that of the 12 in the third break and both the 8 and the 12 at the top, will be appreciated-the production of strong resultant tones being sought and achieved.
should be noted that in both Germany and Italy from the 16th century onwards, with certain exceptions, the use of tierce sounding ranks was eschewed and a little later study of French mixtures indicates a similar position, tierce sounding ranks being used as individual ranks.
The German organ builders did not slavishly adhere to mass breaks at the octave or at any selected point-the principle of breaking one rank at a time was known and followed by individual artist-craftsmen. An example is now given:
Silbermann. Hofkirch-Dresden, giving the composition of Cornet, Mixture and Cymbel:-
Cornet: 1, 8, 12, 15, 17.C.C.G.C.E.No breaks.
Mixtures:1-12. 15, 19, 22, 26.C.G.C.G.
13-24. 12, 15, 19, 22. G.C.G.C.breaking one rank
25-36. 8, 12, 15, 19. C.G.C.G. at a time.
37 - 5, 8, 12, 15. G.C.G.C.
Cymbel: 1-12. 22, 26, 29. C.G.C.
13-24. 19, 22, 26. G.C.G.not a true Cymbel as not
25-36. 15, 19, 22. C.G.C.repeating every octave,
37-48. 12, 15, 19. G.C.G.
49- 8, 12, 15. C.G.C.

Silbermann and others of the period were masters in the design and use of mixture work and while their use was, no doubt, empirical, it has scientific endorsement-but some errors occurred and an unfortunate example was, later, at
Weingarten
Photograph:- By Andreas Praefcke - Self-photographed, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=126695
where the ranks of the Cornet are recorded as:-
1, 8, 12, 15, 19,
and 19 is, of course, incorrect, it should have been a 17: a Cornet must include the 17.

Scores of individual examples could be quoted but lack of time forbids and it will be best to give historical examples of the various types:

Mixture: 3 ranks.
(one break) 15, 19, 22. (two breaks) 15, 19, 22.
8, 12, 15. 8, 15, 19.
8, 12, 15.

Mixture: 4 ranks.
(one break) 12, 15, 19, 22. (two breaks) 12, 15, 191 22.
5, 8, 12, 15.8, 12, 15, 19.
5, 8, 12, 15.

Mixture: 5 ranks.
(two breaks)15, 19, 22, 26, 29.
8, 12, 15, 19, 22.
1, 5, 8, 12, 15.
(four breaks) 15, 19, 22, 26, 29.
12, 15, 19, 22, 26.
8, 12, 15, 19, 22. breaking one
5, 8, 12, 15, 19.rank at a time.
1, 5, 8, 12, 15.

Scharf or Acuta (including tierce sounding ranks):
(1)15, 17, 19. (2)17, 22, 26.
10, 15, 17. 15, 17, 22.
10, 12, 15. 12, 15, 17.
10, 12, 15.

Carillon or Glockenspiel:
(1) 17, 19, 22.(2)15, 19, 22.
15, 17, 19. 12, 17, 22.
12, 15, 17. 12, 15, 17.
10, 12, 15. 8, 12, 15.

Typical Plein-Jeu by Cavaillé-Coll
15, 19, 22, 26, 29, 33, 36.
8, 12, 15, 19, 22, 26, 29.
1, 8, 12, 151 19, 22, 26.
1, 5, 8, 12, 15, 19, 22.
(16), 1, 5, 8, 12, 15, 19.
(16) (10 2/3) 1, 5, 8, 12, 15.

There are many other examples well known to you and perusal of "The Art of Organ-Building" quotes.
I will now give the composition of some mixtures with which I am, naturally, exceptionally well acquainted:

ST. PAUL'S CATHEDRAL: 1872 and to-day exactly as when first installed
Swell Cornet: 3 ranks. 1-24.17, 19, 22.
(Great Furniture 25-43. 12, 15, 17. (Cornet)
is identical) 44 - 8, 12, 15.
(It will be observed that it is only a true Cornet at the first break.)
Great Mixture: 1-20. 24, 26, 29.
(an Acuta) 21-32. 17, 191 22.
33-45. 10, 12, 15.
46 - 3, 5, 8.

WESTMINSTER CATHEDRAL: 1922.
Great Grand Chorus:15, 19, 22, 26, 29.
12, 15, 19, 22, 26.
8, 12, 15, 19, 22.
5, 8, 12, 15, 19.
1, 5, 8, 12, 15.
(The scale of the unison is that of the Great Octave Diapason 4 ft.-the quints are two scales smaller.)

LIVERPOOL CATHEDRAL: 1924-26.
Great Mixture 5 ranks.
1 - 30.12,15,17,19,22.
31- 42.8,12,15,17,19.
43 - 505,8,12,15,17.
51 - 665,8,10,12,15.
Great Furniture 5 ranks.
1-2019,22,24,26,29.
21 - 3312,15,17,19,22.
34 - 465,8,10,12,15.
47 - 663,5,8,12,15.
Bombarde Grand Chorus: 10 ranks on 10-in, wind.
1-20.(16)1,5,8,12,15,19,22,26,29.
21-31.(16)(10 2/3),1,5,8,12,15,19,22,26.
32-42.(16)(10 2/3),1,1,5,8,12,15,19,22.
43-51.(16)(16),(10 2/3),1,1,5,8,12,15,19.
52-(21½)(16),(16),(10 2/3),1,1,5,8,12,15.
Scales: All unison ranks as at CC 8ft.- 6¾. Quint ranks 4 scales smaller. The Sub Unison (16), which runs throughout, is a Bourdon with a prominent harmonic, this for blending and binding purposes.
To deal briefly with combinative stops that are not mixtures in the true sense as there should be no breaks:-
Rauchquint or Quartane: 12, 15, throughout.
Sesquialtera: 12, 17, throughout.
Tertian: 17, 19 (break at the top of the 19 unavoidable)
Each of the above has value and use. It should be noted that the true Sesquialtera has only the two ranks - 12 and 17 _ and it should be of Diapason tonality, not flute.
Mutation: here we enter into a field of intense interest that could well form the subject of an entire lecture, so brevity is essential.
From the historical angle, it will be recognised that the first division of stop groups as at Halberstadt-foundation 8 ft. and all above a mixture was followed by sub-division.
The mixtures took up the story from a division already complete up to the is-but the second upper partial of the 8 ft. - the 12 - found its place either as an individual rank or combined with the 15 as a Rauchquint, mutations above the 15 were found their place in mixtures with, commonly, the tierce as a separately drawn rank.
The mutations of the 8ft. are, of course, 12, 17, 19, etc., and their use in that or octave pitches in appropriate design, is the making of mixtures.
Germany in the latter days of the 18th century and onwards developed a design based upon the Sub-unison, hence the gross-quints and gross-tierces found in specifications of that period: suitably utilised and with discretion, such have great binding power and should not be neglected in the largest instruments.
But it is desired to dwell upon the use of flute mutations and their remarkable qualities in combinational use: this was carried to great heights by, for example, - the 12, 17, 19, ranks having remarkable qualities if correctly designed and used. The Cliquot type of Cornet-whether one stop of ranks drawing individually-was the 12, 15, 17, with the 1 and 8, added on the larger examples, giving the complete Cornet - 1, 8, 12, 15, 17- to which no ranks should be added.
There is one mutation not yet mentioned and that is the b21 -to my mind a most dangerous and undesirable rank for use in mixtures but as a separate rank of undoubted value, especially in tonal synthesis. Apart from the fact that the b21 tends to introduce a grittiness in tonal texture, there is the fact that tuning presents a major problem-so great that in mixtures it is never in tune and its presence, therefore, most unfortunate.
We all know that the 17 needs an artist for correct tuning-the 21 presents almost unsurmountable difficulty.
I finish this talk with a strong plea for the closest possible study of the subject and the use of mixtures and mutations in the right way-always having regard to correct relation with the specification upon which they are to add beauty and embellishment.

Extract from :- Journal of the Incorporated Society of Organ Builders. Published 1947