on quiet days.
Another way of looking at it is to ask what is the "curvature" of the
-earth's surface Over a considerable length, how much does the surface
+earth's surface. Over a considerable length, how much does the surface
deviate (on the average) from perfect flatness. The flat-earth theory
would make it seem that the surface doesn't deviate from flatness at
all, that its curvature is 0 to the mile.
The difference between the longest and shortest diameters is 44
kilometers (27 miles), and that means that the "oblateness" of the
earth (its departure from true sphericity) is 44/12755, or
-0.0034. This amounts to l/3 of 1 percent.
+0.0034. This amounts to 1/3 of 1 percent.
To put it another way, on a flat surface, curvature is 0 per mile
everywhere. On the earth's spherical surface, curvature is 0.000126