Tetley, post one link to one website that supports what you've just said. Otherwise, you're once again making a claim without evidence to support it.
I'll take that one for him.
Eratosthenes of Alexandria
Eratosthenes knew that on the summer solstice
at local noon in the Ancient Egyptian city of Swenet
(known in Greek as Syene) on the Tropic of Cancer
, the sun would appear at the zenith, directly overhead. He also knew, from measurement, that in his hometown of Alexandria, the angle of elevation of the Sun would be 1/50 of a full circle (7°12') south of the zenith at the same time. Assuming that Alexandria was due north of Syene he concluded that the distance from Alexandria to Syene must be 1/50 of the total circumference of the Earth. His estimated distance between the cities was 5000 stadia
(about 500 geographical miles or 950 km). He rounded the result to a final value of 700 stadia per degree, which implies a circumference of 252,000 stadia. The exact size of the stadion he used is frequently argued. The common Attic stadium was about 185 m, which would imply a circumference of 46,620 km, i.e. 16.3% too large. However, if we assume that Eratosthenes used the "Egyptian stadium"
of about 157.5 m, his measurement turns out to be 39,690 km, an error of less than 1%.
Not only did Eratosthenes of Alexandria successfully argue for the Earth being round in or about 240 BC, he got an estimate that was, at most off by a factor of 16%, and with the reasonable assumption that, being in Egypt, he was using the Egyptian standard for a stadia, it was under 1% off.
The Flat earth theory was actually never as prevalent, even during the middle ages, as is often credited to them, although it's adherents during that period were primarily influenced by Biblical passages that presumed a flat earth, as are (in my experience) most flat earthers today.
What do you want though? I'm too lazy to do a whole research paper for the sake of an argument.
You're also too lazy to google "Round Earth", which is all I needed to do (Well, I also clicked the link to open the wikipedia article, and then another one to read about Eratosthenes.). This is a somewhat laxer standard for lazy than "too lazy to do a whole research paper" - many people too lazy to do a whole research paper are not too lazy to google two words. Too lazy to use google is a 'special' kind of intellectual sloth.