What is the poetic form of the poem "Richard Cory" by Edwin Arlington Robinson?

Edward Arlington Robinson's "Richard Cory" is a narrative
poem that has an ironic perspective.  In this narrative, Richard Cory is submerged in
the fastidious, and, as such, is perceived untruthfully by the people "on the
pavement."  For they envision a kingly figure who is "imperially slim, "quietly
arrayed," and polite--"and rich, yes richer than a king."  However, the exalted
adjectives deceive both those who "curse the bread" and the reader.  For, ironically,
Richard Cory leads "a life of quiet desperation" as Thoreau
wrote.

While the economic depression of 1893 impoverished
people, and they struggled to survive, Richard Cory--albeit wealthy--has his own
personal demons with which he struggles.  His wealth has separated him so much from the
ordinary people that he cannot converse with anyone.  When he smiles and says "Hello,"
his greeting goes no further.  The terrible loneliness of Cory may be at the heart of
this narrative poem by Edward Arlington Robinson.