In the last chapter, we reached some firm conclusions about the rhythmic structure that underlies the types of verse that were our prime concern there. Almost all nursery rhymes, ballads, hymns, and other forms of popular verse and song use the four-beat rhythm as the basis of their metre, most often in groups of four lines or in simple variations on this basic structure. Lines with three main stresses usually imply a fourth, unrealised, beat; and lines with six main stresses usually resolve into two units o f three, each with an unrealised fourth beat, as, for instance, in the first line of the poulter’s measure couplet. Similarly, lines of seven main stresses are for the most part felt as two four-beat groups, with a final unrealised beat, as in fourteeners or the second poulter’s measure line. Eight main stresses are interpreted as four plus four, though it is unusual to find lines of this length unless the rhythm is dipodic, making the whole line a larger-scale four-beat unit. The metrical pattern which realises the basic four-beat group is sometimes divided, as in the limerick, where the third group appears as two and two; and occasionally two-beat lines occur alone with the rhythmic effect of a half-line.