The previous answer is generally quite insightful and helpful, but I must correct its mistaken understanding of the poem's meter. It is not in iambic pentameter; in fact, the meter is extremely irregular, varying from line to line. Line 2, for example, is in anapestic tetrameter with an initial iamb....
The previous answer is generally quite insightful and helpful, but I must correct its mistaken understanding of the poem's meter. It is not in iambic pentameter; in fact, the meter is extremely irregular, varying from line to line. Line 2, for example, is in anapestic tetrameter with an initial iamb. An anapest is two unstressed syllables followed by a stressed syllable, while the root "tetra" means four, like a tetrahedron. So there are four anapests in a row. Anapests create the feeling of galloping along. We are familiar with anapestic meter that begins with an iamb from the limerick form:
There WAS a young LAdy named MAY
Who READ a love STOry each DAY
There are only two anapests in each of these lines, but it's the same gallop that makes the limerick funny, though humor is not always the effect. Sometimes, the gallop can simulate a heart beating faster, for example. So when Birney writes, "All WEEK in the VALley for WAGes in AIR that was STEEPED," he is simulating the feeling of their hard work's rhythm.
Line 9 creates even more of a galloping feeling, with no initial iamb for a deep breath: "Into VALleys the MOON could be ROLLed in. ReMOTEly unFURLing." Note the association of anapests with valleys for Birney. This line also has what's called a feminine ending—that is, a single unstressed syllable attached to the end of the line.
The lines vary radically throughout the poem: line 13 alternates anapests and iambs; line 21 gets into dactyls—the opposite of iambs, with one stressed syllable before two unstressed; line 33 goes back to the same meter as number 2. All this is to say that metrical regularity is definitely not an element of this poem, even as a standard framework against which the rhythm can ebb and flow. I could not find even a single iambic pentameter line in it, at least not in the first five sections. So be sure not to assume a metrical regularity when you write about this piece.