Anecdote of the Jar
The sounds of this poem are round and smooth. We imagine them floating around our tongue just like the glass of a jar would feel in our hands. We hear the word "round" itself twice, but get that same sound in the words "surround," "around," and "ground." We also hear a lot of "air" in "everywhere" and "bare."
So, the dominant sounds in this poem are soft, smooth, and easy to deal with. There's no set rhyme scheme, but there's lots of repetition, and for the most part, there's a steady four beats to a line, in a pattern called iambic tetrameter (check out the "Form and Meter" section for more on this).
But just like the jar, alone in the wilderness on the Tennessee hill, there are some parts of the sounds of this poem that don't quite fit. First of all, we've got the word "jar" itself. The noise of this word is just like that—a noise. It's more clunky, forced, and strange than the rest of the smooth and easy sounds in the poem. We've also got lines like line 8:
And tall and of a port in air.
This stands out as rough after the super-smooth line 7 ("The jar was round upon the ground"). If you read line 8 aloud in the four beat a line rhythm, the word "of" sticks out.
So pay attention to these tiny bumps in the rhythm of the poem. We're betting that they are there because their... jarring effect catches our attention, letting us know that there's conflict in the world of this little poem, even in its sounds.