Apologies, confusion between childhood books and fact. According to the books, Columbus thought the earth was round in sea of unbelievers who took it as almost

Apologies, confusion between childhood books and fact. According to the books, Columbus thought the earth was round in sea of unbelievers who took it as almost religious fact that God made the earth flat. Or summat. Anyway, as you point out, everyone who gave it much thought knew the Earth to be round. Columbus' error was being bad at math.