It would be unnecessary in general to translate passages of this kind into correct notation before performing them, as in most cases the key-relations would be tolerably clear, in whatever way they were written. Should there be any chance of error in taking the accidentals literally, a large acute or grave mark might be drawn across the staff, to indicate that the notes are to be played twelve Fifths higher or lower than they are written. In the present instance, the acute mark could be used.
Sometimes the enharmonic change is real, and not merely a device of notation. Take the following extract from 'The people shall hear' in the 'Israel in Egypt':—
Here B♭ must be played in the second bar and A♯ in the third, a modulation which is rendered easy by the general construction of the passage. 'Enharmonic changes (Helmholtz remarks) are least observed when they are made immediately before or after strongly dissonant chords, or those of the Diminished Seventh. Such enharmonic changes of pitch are already sometimes clearly and intentionally made by violinists, and where they are suitable even produce a very good effect.'[1]
The necessity of avoiding 'wolves' in the meantone system sometimes restricts the choice of notes. Thus in a passage in the 'Lachrymosa' of Mozart's Requiem:—
the discord A♭—F—B♭—E♭ must be played exactly as it is written, owing to the B♭ and E♭ being prepared. Even if G♯ stood in the text, A♭ would be substituted in performance, as the 'wolf' G♯—E♭ is inadmissible. All such difficulties can be solved in a similar way. On the other side, we have to reckon the great variety of chords and resolutions which are available in the meantone system, but have no existence in equal temperament. Many chromatic chords may have two or more forms, such as the following:—
each of which may be used according to the key-relation of the context, or the effect required in the melodic parts. Again, the Augmented Sixth is much flatter in the meantone system than in equal temperament, slightly flatter even than the interval called the Harmonic Seventh. When the strange impression which it causes at first has worn off, its effect is peculiarly smooth and agreeable, especially in full chords. It is also available as Dominant Seventh, and may be written with the acute mark (G—/F), to distinguish it from the ordinary Minor Seventh got by two Fifths downwards (G—C—F).
It is important to recognise the fact that the forms of chords can only be settled by actual trial on an instrument, and that the judgment of the ear, after full experience of the different modes of tuning, cannot be set aside in favour of deductions from any abstract theory. Practice must first decide what chord or progression sounds best; and this being done, it may be worth while to ask whether theory can give any reasons for the ear's decision. In many cases our curiosity will be unsatisfied, but our preference for one effect rather than another will remain unchanged. Neither can theory solve those questions which sometimes arise as to the correct mode of writing certain chords. All questions of notation can only be decided by playing the disputed passage in some system of tuning which supplies a separate sound for each symbol. The reason why G♭ and F♯ were not written in the same chord was a purely practical one; these two signs originally meant different sounds, which formed combinations too rough for use. Our notation having been formed long before equal temperament came into use, it is not surprising that the symbols, do not correspond with the sounds. But they correspond exactly with the meantone scales, and it is on this system of tuning that all our rules of notation are founded. 'It is only necessary to remember that we have here the original system, which belongs from the very beginning of modern music onward to our musical notation, to see that by employing it we have the true interpretation of our notation; we have the actual sounds that our notation conveyed to Handel, to all before Bach, and many after him, only cured of the wolf, which was the consequence of their imperfect methods.'[2]
To carry out any system of temperament consistently in the orchestra is practically an impossible task. Tempered intervals can only be produced with certainty on a small number of the instruments, chiefly the wood-wind. The brass instruments have an intonation of their own, which differs widely from either of the temperaments we have described. Thus the French horn, whose notes are the harmonics
