In THE ANVIL by the great Rudyard Kipling we hear an (I think) unprecedented rhythm. In each of the three stanzas the lines are arranged with six stresses in the first line, five in the second, six in the third and seven(!) in the last. 6-5-6-7! Who else but Kipling would have dared? The miracle of the poem is that the oddity of the line length does not (at least to my ear) intrude on our minds as we read it. It is hardly noticable.
But what it does for us is important. By starting with a long line he sets the standard. Then in the shorter (5 stress) line we feel a release and freedom in reading, thus our voice becomes naturally a couple of notes lower--perfect for a foreshadowing line. Then back to the standard, the six stress before we move in the opposite direction. The final line of each stanza, with its extra syllable that we feel pressed to squeeze into our mouths with an equal amount of breath as we used in what he had set up as the standard, is tense. The effect is that our voice naturally raises a few notes. We feel and hear tension, not only in the thoughts of the poem, but in our own voices! And that happens naturally, whether we are paying attention or not. His variation of line length is not accidental, but integral to the overall effect of the poem.
England's on the anvil--hear the hammers ring--
Clanging from the Severn to the Tyne!
Never was a blacksmith like our Norman King--
England's being hammered, hammered, hammered into line!
England's on the anvil! Heavy are the blows!
(But the work will be a marvel when it's done.)
Little bits of Kingdoms cannot stand against their foes.
England's being hammered, hammered, hammered into one!
There shall be one people-- it shall serve one Lord--
(Neither Priest nor Baron shall escape!)
It shall have one speech and law, soul and strength and sword.
England's being hammered, hammered, hammered into shape!