Flat earthers claim we can see too far for the earth to be a sphere. They actually never test it. They also miss the elephant that for flat earth you cannot ever see far enough and bottoms of distant objects are obstructed, contrary to all known behavior of light.
When “testing the globe” you need to use the globe when you are testing. Flat earthers rarely use the globe, instead, they use their misunderstanding of the globe. When testing a “See too far” claim, they typically use the wrong formula to start. They love “8 inches per mile squared”. They actually have no idea where this formula came from, nor how to properly apply it.
The proper application of “8 inches per mile squared” is for the linear drop from a horizontal. Take a theodolite or auto level, measure to some distant object. The drop from 90° is the proper usage for “8 inches per mile squared”.
They are so unaware of how to properly apply this formula that they try to use it for everything.
Chicago Skyline from Michigan
A photo of the Chicago skyline taken from Grand Mere State Park in Stevensville Michigan shows the skyline of downtown Chicago.
Flat earthers claim ridiculous amounts of predicted obstruction, never bothering to include the observer’s height. They also tend to get sloppy on the distance. The observer was 180 feet above the water and the distance to downtown Chicago is 53 miles.
When analyzed using an earth curve calculator that has the capability to adjust for common conditions near water, the predicted hidden of the Willis Tower is about 300 feet. The tower is 1450 feet tall. There is no problem at all with the observation on a globe.
However, the bottom of the city is obstructed by the water. Either Chicago is flooded, or the earth is not flat.