"Celestial choir! enthron'd in realms of light, Columbia's scenes of glorious toils I write. While freedom's cause her anxious breast alarms, She flashes dreadful in refulgent arms. See mother earth her offspring's fate bemoan, And nations gaze at scenes before unknown! See the bright beams of heaven's revolving light Involved in sorrows and the veil of night!"
I am assuming that the above quotation is the excerpt of the poem that we need to read before answering the question above question.
The iambic pentameter in the poem creates an even RHYTHM and complements the poem as a SORROWFUL ELEGY.