NASA and modern astronomers claim we are living on an oblate spheroid 25,000 statute miles in equatorial circumference with a curvature of 7.935 inches to the mile, varying inversely as the square of the distance, meaning in 3 miles there is a declination of nearly 6 feet, in 30 miles 600 feet, in 300 miles 60,000 feet and so on. Therefore, if we wish to prove or disprove the validity of their convexity claim, it is a fairly simple, straight-forward matter of measurements and calculations.
For example, the distance across the Irish Sea from the Isle of Man’s Douglas Harbor to Great Orm’s Head in North Wales is 60 miles. If the Earth was a globe then the surface of the water between them would form a 60 mile arc, the center towering 1944 feet higher than the coastlines at either end! It is well-known and easily verifiable, however, that on a clear day, from a modest altitude of 100 feet, the Great Orm’s Head is visible from Douglas Harbor. This would be completely impossible on a globe of 25,000 miles. Assuming the 100 foot altitude causes the horizon to appear approximately 13 miles off, the 47 miles remaining means the Welsh coastline should still fall an impossible 1472 feet below the line of sight!