Here is a place to let your words do your talking for you.
Wow, that is really interesting, I never knew that!
Are you going to write again soon? 
Ignorance is seizing on one man's widely discredited paper (see: Inventing the Flat Earth, above) and claiming it to be proof of the ignorance of progressives. Ignorance is seeking to place the acquisition of knowledge in reverse. Ignorance is the failure to recognize what is real today and the failure to acknowledge what was wrong with yesterday.
Ignorance is seizing on one man's widely discredited paper...
That's a false claim. As for evidence with respect to the ignorance of progressives numerous editorials could be cited in which the flat earth myth is cited as an example of Progress or used against conservatives who disagree with progressives, etc.
Hi Mynym:
You are right.
Back in about 300 BC, Eratosthenes basically measured the angle of the shadow of the sun at noon on a certain day when it was straight overhead at Syene [Aswan]. At Alexandria, more or less due N by a known distance, it was at a certain angle from Vertical. From that, he inferred the circumference of the Earth, well within 10% on reasonable assumptions about how many Stadia make a mile or a kilometre . . . 10,000 km is 1/4 circumference, more or less -- by design; and oddly the inch is about 1/500 000 000 of the N-S diameter, pole to pole.
Before that, Aristotle I think it was argued that since the shadow of the earth on the moon in a lunar eclipse is always round , the earth is the shape that does that: a sphere.
The debate with Columbus was that his estimate for circumference was far, far too low.
(Remember he was trying to reach ASIA by sailing W, for 90 days or so, at Caravel sailing rates, 90 * 150 mi/day = 13,500 mi. 150 mi/day = 6.25 mph. You have to get to a more unrealistic average of 10 mph, before you are looking at 21 - 22,000 mi in 90 days. Sailing ships of that general era had a very hard time crossing the Pacific, as Magellan's voyage shows!)
What CC did was to recognise the implication of tropical trade winds pushing generally Westwards, whether with a S or N wards component, and of temperate ones pushing generally eastwards. He could sail S, sail W, then back N and home. And, he had evidence of something out there, including washed up canoes with bodies on the coasts of Ireland, as I recall.
GEM of TKI
The debate with Columbus was that his estimate for circumference was far, far too low.
And it was, if the Americas were not here and he really had to sail to where he thought he was sailing (thus the name "indians" and so on) he would have perished.
Commenting by HaloScan
