Since when have we known that the Earth is a Globe?

Extract

There are still people who believe that only during the last four-hundred years have we known that the Earth is a globe. They were taught this at school when they were told the story of Christopher Columbus. Columbus, it was said, went to King John of Portugal with the proposal to reach the fabulously rich Cathay, situated in the Far East, by sailing across the Atlantic Ocean to the west. The king consulted a committee of mathematicians who rejected the idea with scorn. The Earth was round and flat like a trencher, they said, and not a globe as Columbus maintained. And some teachers added that not until the circumnavigation of Magellan's ship, Victoria, was there any proof of the shape of the Earth.