; for in this case the phrasing cannot be indicated clearly without dividing the beat.
2. When there is a ritardando and it becomes necessary to give a larger number of beats in order to show just how much slower the tempo is to be. The second point is of course covered by the general rule already referred to.
The conductor must train himself to change instantly from two beats in the measure to four or six; from one to three, et cetera, so that he may be able at any time to suit the number of beats to the character of the music at that particular point. This is particularly necessary in places where a ritardando makes it desirable from the standpoint of the performers to have a larger number of beats.
THE DOTTED-QUARTER AS A BEAT NOTE
Although covered in general by the preceding discussion, it may perhaps be well to state specifically that the compound measures 6-8, 9-8, and 12-8 are ordinarily taken as duple, triple, and quadruple measures, respectively. In other words, the dotted-quarter-note (
) is thought of as the beat note, some modern editors going so far as to write
in place of 6-8 as the measure sign;