Christopher Columbus Believed in a Smaller Earth Than Eratosthenes Had Measured and That Is Why He Sailed
The Eratosthenian Earth circumference (about 250,000 stadia, accurate to 2%) was the standard ancient figure but had been substantially undermined by a competing late-antique calculation by Posidonius. Columbus took the smaller Posidonian figure as his planning baseline. If he had used Eratosthenes's number, he would never have sailed.
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