Why is the ninth month called September?
in musical notation, sign that indicates the metre of a composition. Most time signatures consist of two vertically aligned numbers, such as , , , and . The top figure reflects the number of beats in each measure, or metrical unit; the bottom figure indicates the note value that receives one beat (here, respectively, half note, quarter note, eighth note, and sixteenth note). When measures contain an uneven number of beats falling regularly into two subgroups, the division may be indicated as, for instance, instead of