Jonson's short poem is written mostly in iambic pentameter, the most common meter in English poetry. Each line of iambic pentameter contains five (pent-) groups, which we call feet. Each group consists of an unstressed syllable, followed by a stressed syllable. Take a look at line 9, for example: "Like mel-ting snow u-pon some cragg-y hill." "Like mel" is an iamb, and it's followed by four more. Voilà! Iambic pentameter.
By the way, line 11 also contains all iambs, but it contains six groups (feet). A line with six feet is called a hexameter, and thus the last line of the poem can be classified as iambic hexameter. Phew.
Not every line in the poem is as neat as lines 9 and 11, though. Jonson wouldn't want us to get bored, now would he? Take the first line of the poem as an example: Slow, slow, fresh fount, keep time with my salt tears. The line is composed almost entirely of spondees, a group of two stressed syllables, which makes us slow down as we plod through all the stressed syllables.
But we can't forget that shy fourth foot, which contains two unstressed syllables. This is called a pyrrhic, and it usually only occurs next to a spondee. There is another line in the poem that contains all spondees. Can you locate it? What effect do all these spondees have on your reading of the poem? Do you think they help to reinforce its themes?
It wouldn't be a "Form and Meter" section without a little shout out to poetry's oldest friend: rhyme. "Slow, Slow, Fresh Fount" has lots of it, and those rhymes fall into a nice, neat pattern we call a rhyme scheme. The rhyme scheme for the poem is as follows: ABABCCCDDED. In the scheme each letter represents the end of a line. The lines marked "A" rhyme with each other, as do those marked "B," and "C," and so on.
The strange thing is, what starts off as a stock and standard ABAB alternating rhyme quickly becomes something quite different. Check out those three C's (lines 5-7) in the middle of the poem, and that one lone wolf (line 10) that has no rhyming partner. When you hear these rhymes, how do you feel? What effect do they have on you? Do they slow you down? Speed you up? Do you think Jonson was being sloppy? Probably not.
We also can't forget that, form-wise, this is a song. If you were singing it, how would it go? We're betting it would be a slow jam. Are we right or are we right?