What literary device does Poe use in the following line And silken sad uncertain rustling of each purple

The literary device Poe uses in the line "And silken sad uncertain rustling of each purple" is alliteration. Alliteration is the repetition of the same consonant sound at the beginning of two or more words. In this case, the consonant sound "s" is repeated in the words "silken," "sad," "uncertain," and "rustling." This repetition creates a sense of rhythm and musicality in the line.