[12.]—The commonest errors in simple time are not in regard to notes, but rests. This is because silence cannot be divided or syncopated, and therefore that would often be quite right as a representation of sound which is quite wrong as a representation of silence. Thus a beat should not be represented by two rests where one would do, though it might be by two notes (see a, [Fig. 7]). Nor one rest represent parts of two beats (see b, [Fig. 7]). Nor one rest represent an unaccented and an accented beat (see c, [Fig. 7]). In triple time it is better to avoid a single rest representing the latter and greater part of a measure (see d, [Fig. 7]), indeed, it may be said that half-note rests should not be used in triple time.
Fig. 7.
[13.]—But in compound time errors, if not more numerous in kind, are much more common anyway in regard to notes as distinct from rests. A note should never be written which represents a beat and part of another. The commonest violation of this principle—and it is very common—is in writing a dotted half note in six-eight time; this divides the measure into three thirds instead of two halves, by representing a beat-and-a-third and two thirds of a beat (see a, [Fig. 8]). A beat-and-a-third, if required, should be represented by a note of the value of a beat tied to one of the value of a third, never by a single note equalling both—a half note in this case (see b, [Fig. 8]). A similar principle applies to rests. A measure's silence should be represented by rests divisible into beats, not by rests which fuse a beat and part of the next (see c, [Fig. 8]). Two dotted quarter notes in twelve-sixteen time are not so bad as a dotted half note in six-eight time, as they correctly represent the division of the measure into two halves, but they misrepresent these halves as consisting of three sixths of a measure whereas they rhythmically consist of two quarters (see d, [Fig. 8]).
Fig. 8.
A twelve-sixteen measure of silence is much easier to write, since it can be done by a single whole note rest, which is also commonly used as a measure-rest, irrespective of the value of the measure. (Hence the German name taktpause.) The six-eight measure of silence (see c, [Fig. 8]) might also, of course, have been written in the above way, or by quarter, eighth, quarter, eighth rests in place of the dotted rests.
Placing of Notes.