Farther Vs. Further Poem by Stanley Cooper

The use of proper English just astounds me
The American poem creator that I am
The use of “further” or “farther” just confounds me
Their nuances are as foreign as Siam

How will I ever speak concisely?
With my Lack of “farther” “further” expertise
I reckon I would speak much more precisely
If I spoke, instead of English, Siamese

This poem has gone on “further” than it should have
Or is “farther” more English-y precise
To ascertain the more correct way, I could have
Simply rolled a lucky pair of dice

I ask you with much fervor
Since my brain’s now all at sea
Is it farther or is it further?
It’s a puzzlement for me