How would You prove the World is Round?

[Heyo]

If "all the knowledge of previous generations has been lost in the mists of time", we would be back to hunting and gathering. My fellow cave dwellers would write me off as a nut case for contemplating whether the Earth is round or not. We would have more pressing issues to wrestle with.

My fellow cave dwellers would write me off as a nut case for setting sail to a land they can't see but they'd be happy to trade the goods I bring back.

 

[Jedster]

This photograph taken by my extra-spacial camera proves the world is not round