I think you are talking about the curvature calculation of 8" per miles squared there is a problem here, the curvature can not be observed and this goes back hundreds of years starting of here with the Bedford level Experiment <iframe width="420" height="315" src="
https://www.youtube.com/embed/VWl1pWiMLyo" frameborder="0" allowfullscreen></iframe> no curvature observed over 6 miles and there should be 16 ft but now we have the Chicago skyline seen from Michigan 60 miles away it should be a full 2,600 feet below the curvature Sears tower is only 1,482 ft so you should not see anything below 1,118 ft above the sears tower 2.600 feet, there is Zero curvature because it's flat <iframe width="560" height="315" src="
https://www.youtube.com/embed/aLlNKy5j_O8" frameborder="0" allowfullscreen></iframe>.