Is 686 chains as long as The Diameter of Earth?
It's about one-nine-hundredth as long as The Diameter of Earth
The length of The Diameter of Earth is about 634,110.450 chains.
(Equatorial)
The Earth — not a perfect sphere, but rather an oblate spheroid with bulged middle — has a diameter of approximately 634,110.450 chains at the Equator. The first complete view of Earth's diameter was in a photograph taken from a V-2 rocket launched in 1946 by the United States Army, which reached an altitude of 5,200 chains.
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