Using Eratosthenes' results in measuring the angle of the sun's elevation (7.2 degrees), I have determined the sun's elevation to be 3,958 miles or approximately 4,000 miles. Proof is shown below:

The angle of the sun's elevation between Syene and Alexandria during Alexandrian noon of the summer solstice is 7.2 degrees. The distance between Syene and Alexandria is approximately 500 miles. If I divide the 500-mile distance by the tangent of 7.2 degrees, the resulting elevation becomes 3,958 miles.

Thus I have corrected the 3,000 mile calculation of Rowbotham and his contemporaries.