Shelley wrote “Ozymandias” in iambic pentameter, meaning that, on average, each line in the poem consists of five iambs. (Recall than an iamb has one unstressed syllable followed by a stressed syllable, as in “re–mains.”) Given that the poem approximates the sonnet form, iambic pentameter is an unsurprising choice, since English-language sonnets are typically written in this meter. For such a short poem, however, it’s worth noting the frequent metrical variations Shelley has introduced to the rhythm. In most cases, the divergences from strict iambic rhythm involve simple substitutions of trochees (stressed–unstressed), which reverse the stress pattern of the iamb. As a representative example, consider lines 10–14:

     My name / is O- / zy-man- / di-as, / King / of Kings;
     Look on / my Works, / ye Might- / y, and / de-spair!
     No-thing / be-side / re-mains. / Round the / de-cay
     Of that / co-lo- / ssal Wreck, / bound-less / and bare
     The lone / and le- / vel sands / stretch far / a-way.

All five lines in this passage have a clear iambic rhythm, but only the final line is in strict iambic pentameter. Each of the middle three lines features a trochee substitution, either in the first or fourth foot. Indeed, the third line has a trochee in both positions. These substitutions add texture to the poem’s language and prevent the kind of predictability that comes with perfectly strict rhythm.

Aside from the trochee substitutions, the passage quoted above also features a line that is noteworthy for the way it strains the pentameter line. The opening line of that passage is in fact an example of a six-foot, or hexameter, line. Admittedly, it’s possible to read this line as pentameter. But to do so requires the elision of the final two syllables in Ozymandias’s name:

     My name / is O- / zy-man- / dias, King / of Kings

If the reader doesn’t force this elision, then it becomes clear that the line has six stressed syllables rather than just five. However, this distribution of stresses introduces a new problem of scansion, since it means that the penultimate foot in the line is missing its initial unstressed syllable. It’s almost as if the word “the” is missing from the line:

     My name / is O- / zy-man- / di-as, / [the] King / of Kings

The subtle metrical complexity of this line is significant. Most obviously, the way it exceeds the pentameter limit references how Ozymandias aspired to have his outsized reputation last beyond his own lifetime. Yet the missing unstressed syllable also quietly reflects everything that time has caused to collapse and fall away, leaving Ozymandias little more than a name carved in crumbling stone.