The Greek World around 450 BC This is the Golden Age of Athens, the time of Pericles and Socrates. Very few ordinary citizens would have travelled outside this area. Athens Alexandria Troy

The “sinking” appearance of a departing ship relative to the observer’s horizon. Observational evidence for a Spherical Earth

All of the ship would remain visible as apparent size diminishes. Whereas on a flat Earth

Positioning on the Earth’s Surface Latitude and Longitude together enable the fixing of position on the Earth’s surface.

Can you figure out what he did and arrive at an estimate for the circumference of the Earth? Eratosthenes measured angle  as approximately 7½o Taking the true value as 25,000 miles, find his percentage error. 4% Alternate angles are equal.