A Terrible-y Petrarchan Sonnet
As we mentioned over in the "In a Nutshell" section, "Carrion Comfort" is one of a group of Hopkins' poems known collectively as the "terrible sonnets." Given that, it would be pretty weird if this poem were written in a form other than a sonnet. (Of course, it's also a little weird that "terrible" refers to the subject matter of Hopkins' depression, not the quality of the poems themselves.)
Specifically, what we have here is a Petrarchan sonnet, which features a rhyme scheme that reads ABBAABBA CDCDCD, where each letter is that line's end rhyme. Petrarchan sonnets typically consist of an eight-line stanza known as an octave, followed by a six-line stanza called the sestet.
The octave in a Petrarchan sonnet typically acts as the set-up for the poem's investigation, while the sestet includes a "volta," or turn, starting in line 9 and advancing a comment on that set-up that carries forward to the end of the poem. In the case of "Carrion Comfort," the speaker details the horrors of his despair in the octet, but then in the final sestet he turns to contemplate why he had those awful experiences to begin with.
Form and rhyme-wise, then, this poem is fairly straightforward. And then you get to the meter.
Typically, Petrarchan sonnets are consistent when it comes to their rhythmic patterns, but Hopkins was not big on consistency. Instead, he favored something he called a "sprung rhythm," which was his attempt to mimic the more natural patterns of human speech. To do that, he liked to put the stress on the first word of a line and also vary the number and consistency of his metrical feet.
As a result, a Hopkins poem can feel all over the place in terms of its meter. Just try to find a pattern in this line:
In me , most weary, cry I can no more. I can; (3)
It seems to be alternating between trochees and iambs, but even then it adds a final stressed syllable at the end of the line.
Also, note the accent over the word "ór." Hopkins used these accent marks to indicate words that should be stressed. He clearly thought long and hard about how to make each line sound as natural to human speech as possible. So, even though he was using a time-tested form in the Petrarchan sonnet, Hopkins made sure he put his unique rhythmic spin on things, which explains why a lot of readers get dizzy after they read his work.