I really don't see what I am doing mathematically that is all that complex compared to those AE's. Just using modern conveniences of a calculator to do those same old tedious ancient fraction calculations is all. Who's to say that interesting diagram of yours wasn't known to the AE's as well, only they scaled it up a bit to encompass Global dimensions. In the book called Ancient Geometry by Tons Brunes, he demonstrates a very primitive geometric square to circle Pi method, that I later realized was the sq.rt. of 10 or 3.16227766. How about I use that value on that OM unit Diameter 7875 Mi.,that Jim has recalled up to get a Circ. of 24,902.93657 Mi., which is only a hair's difference from my own model's calculation of the Equatorial Circ. of 24,902.34375 Mi. .59282 Mi. difference. Not bad at all really for such a primitive value of Pi, don't you think?