Back to the meters, many hymns are set to folk tunes - if you look in the back of most hymnals, you find a listing by tune name, source, and even the meters. I tried counting out the meters to some of the songs in one of my folk song books. It's hard to do, but basically, you just count the syllables in each line, through enough verses to identify the pattern. It's a huge project - probably for someone really bored, but it would be a way to reattach lyrics to songs that had been appropriated for church use.