The method of using three instruments of the same timbre in widely-divided three-part harmony is inferior:
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But if the third instrument is of low register (Bass Fl., Eng. horn, Bass cl., or C-fag.), the resonance will be satisfactory:
In chords of four-part harmony, three instruments of the same timbre should be combined with a fourth instrument of another:
In writing chords of 5, 6, 7 and 8 part-harmony, whether they are independent, or constitute the harmonic basis, the student should follow the principles outlined in the previous chapter, dealing with the progression of wood-wind instruments in octaves. As the 5th, 6th, 7th and 8th notes are only duplications in octaves of lower notes of the real harmony (in 4 parts), instruments should be chosen which combine amongst themselves to give the best octaves. The process of crossing and enclosure of parts may also be used.
A. Wood-wind in pairs (close distribution):
In widely-divided harmony chords in several parts are to be avoided as they will entail both close and extended writing:
_Note._ In the majority of cases this distribution is employed when the two upper harmonic parts have a special melodic duty to perform--this question is discussed above.
Overlaying of parts is the most satisfactory method in dealing with close three-part harmony. Crossing of parts is not so favourable, as octaves will be produced contrary to the natural order of register:
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A. If the wood-wind is in pairs it is a good plan to mix the doubled timbres as much as possible:
In chords of four-part harmony the classical method may be adopted:
In this case, though the high _C_ in the flute is fairly powerful, the resonance of the _G_ and _E_ in the oboes is softened by the duplication of the 2nd flute and 1st clarinet, while the _C_ in the 2nd clarinets (not doubled) is feeble in comparison with the other notes. In any case the two extreme parts are the thinnest and weakest in tone, the intermediate parts the fullest and strongest.
B. _Wood-wind in three's_ admit of perfectly balanced mixed timbres in chords of three-part harmony:
These timbres may even originate from three-fold duplication: