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These empty spaces create a bad effect especially in forte passages. For this reason widely-divided harmony, which is fundamentally based on the extension of intervals, can be used but seldom and only in piano passages. Close writing is the more frequent form in all harmony devoted to the wood-wind, forte or piano.
2. As a general rule a chord of greatly extended range and in several parts is distributed according to the order of the natural scale, with wide intervals (octaves and sixths), in the bass part, lesser intervals (fifths and fourths) in the middle, and close intervals (3rds or 2nds) in the upper register:
3. In many cases correct progression of parts demands that one of them should be temporarily doubled. In such cases the ear is reconciled to the brief overthrow of balance for the sake of a single part, and is thankful for the logical accuracy of the progression. The following example will illustrate my meaning:
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In the second bar of this example the D is doubled in unison on account of the proximity of the three upper parts to their corresponding parts an octave lower. In the fourth bar the F is doubled in unison in both groups.
4. The formation of the harmonic basis, which is essentially in four parts, does not by any means devolve upon the wood-wind alone. One of the parts is often devoted to the strings, arco or pizz. More frequently the bass part is treated separately, the chords of greater value in the three upper parts being allotted to the wood-wind. Then, if the upper part is assigned to a group of strings, there remains nothing for the wind except the sustained harmony in the two middle parts. In the first case the three-part harmony in the wood-wind should form an independent whole, receiving no assistance from the bass; in this manner intervals of open fourths and fifths will be obviated. In the second case it is desirable to provide the intermediate parts with a moderately full tone, choosing no other intervals except seconds, sevenths, thirds or sixths.