Wednesday's Random Slang-o-rama: Flop-up and sot-down

Here's a pair of interesting expressions: flop-up and sot-down. I'd hate to even venture a guess as to their meaning...
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However, I don't have to guess, because Americanisms, Old and New by John Stephen Farmer provides a tidy definition of both:

Flop-up.—A day's tramp; a sot-down being equivalent to half a day's travel. Flop-up time is bedtime.

And here is the example offered, straight from the Detroit Free Press, September 15, 1888:

"Stranger, did ye lope it?"**
"Yes."
"A mile or a sot-down?"
"More'n that. About a dozen flop-ups."

I guess my little daily perambulations through the neighborhood don't count as even a quarter of a sot-down...

Going for a flop-up or a sot-down?
(Travelers in Hilly Countryside c. 1650, Aelbert Cuyp [Public domain])

** (In other words, did you come on foot.)