Many of Dickinson's poems have a singsong, hymn-like quality, and that's because they're mostly written in ballad stanza. (It's no coincidence that you can sing pretty much any Dickinson poem to the tune of "Amazing Grace" – they're written in this same meter.) Poem in ballad stanza are written in quatrains of alternating iambic tetrameter and trimeter, with an ABCB rhyme scheme.
What does that all mean? Let's break it down piece by piece.
First up, iambic. This poem has the rhythmic, da-DUM da- DUM da- DUM feeling of an iambic meter. An "iamb," a popular kind of metrical "foot" (or unit), is made up of two syllables, the first unstressed (da), and the second stressed (DUM). When you put several iambs in a row, you get that two-step rhythm that makes Dickinson so fun and easy to read aloud.
This particular form has alternating lines of four and three iambs. When lines have four iambs we call that "iambic tetrameter" (tetra = four, as in Tetris); when they have three iambs we call that "iambic trimeter (tri = three, as in triangle).
Make sense? No? Yes? Maybe? To be safe, let's read aloud together. Below we've put slashes between each of the iambs, and put the stressed syllables in bold. Try to really exaggerate the difference between stressed and unstressed syllables to feel the even beat of these lines:
The Light-|ning is | a Yell-|ow Fork
From Tab-|les in | the Sky
Get it? As for rhyme, you can easily pick out the rhyme pattern here, even when it's a little wonky. The last words in the second and fourth lines of each stanza rhyme. This is commonly called an ABCB rhyme scheme. Check out the second stanza to see what we mean:
Of mansions never quite disclosed (A)
And never quite concealed (B)
The Apparatus of the Dark (C)
To ignorance revealed. (B)
This works out beautifully here, because the words marked with a "B" rhyme ("concealed" and "revealed"). However, in the first stanza the last words in the second and forth lines ("sky" and "Cutlery") aren't a perfect rhyme. They're what's called a slant or sight rhyme. That is, we can see that the two words "rhyme" because of their common ending, but it doesn't sound exactly right when you read it out loud. That's not an accident – rather, it's one of Dickinson's trademarks, and the common occurrence of slant rhymes in her poems keeps them from being dully consistent in form (in our humble opinion).