You guys just posted links to two calculators, created by individual authors, which give different results to each other.
Yet that somehow demonstrates Rowbotham and the entire scientific community of the 1800's to be wrong?
Both calculators give the exact same result. Use any number in both calculators.
Actually, both calculators give
similar results: the one I linked to uses slightly more sophisticated and therefore accurate trigonometry.
Both calculators also agree, more or less, with "8 inches per mile squared" - thereby validating Rowbotham's simplified, 'ball park' equation.
"8 inches per mile squared" is only useful up to about 100 miles, though - after which something more precise is required.
For most practical purposes, though, it suffices for measuring "the drop".
Though, as stated above, "the drop" isn't that useful: "hidden amount" more so.
Are you a Flat Earther or Round Earther? Either way, you contradict both of them.
How can I contradict them with a question? (I.e., "what is the correct equation?")
I'm a 'Round Earther'.