When you realize that the dimensions of the Great Pyramid of Giza are a reduction of the earth’s northern hemisphere by a factor of 43,200, the denomination of the hindu yugas of time, it becomes obvious that the calculations were from the rate of precession, the slow wobble rate of the earth’s axis, 72 years/degree, a base six number proving that a six-sided polygon (hexagon) was circumscribed by a geometric circle of the earth to have determined the radius length of the earth against the backdrop of the stars (see now article #2 at http://iceagecivilizations.com), and so thereby, the circumference length of the earth.
Mainstream scientists don’t want to digest and disseminate this ancient geometric mapping method because it legitimatizes scientifically the Maps of the Ancient Sea Kings (Hapgood), the ancient source maps for those medieval maps demonstrating ancient navigation of all the world actually during the ice age. This notion is unthinkable to those of the darwinian bent, but within the young earth creationism template, it makes perfect sense, the ice age having ended actually circa 1500 b.c. corroborated by that Plato wrote of bronze age ships, cities, and technology in his account about Atlantis. Refer to http://genesisveracityfoundation.com.