...a sphere with a radius of the exact value for pi in MILES 3141.592653 miles gave a volume which is half that of the planet Earth.
The coffer seems to me to be similar to the Heart of, or perhaps the brains of the concept behind the Giza complex.
An interesting thought, Jim.
From 'as above, so below', perspective: representing stars, the Memphis pyramid cartography -- scale: Giza to Meidum -- portray the Globe from equator to the N.pole. The 1/2 sphere measure is corroborated by the GP shafts, that target the celestial equator & celestial pole -- respectively defined by Earth's geometry -- its girth & apex (polar finite).
The World's rotational speed, through 360degrees, is measurable by means of G3 causeway, in alignment with d-Orionis aka the star Mintaka. Such is accordingly determinable by its alignment with the Sun on equinox day.
a.o. G1 represents a Solar/tropical year - reiterated by its causeway, in conjunction with that of G2, whereby the slant of the polar axis is captured at minimum in its gyration cycle. Its two turn-around points, coinciding with the 180deg. reversal of the equinoxes, incur 14deg. & 58deg. obliquity - opposite respective the vertical. True Polar wander, therefore, occurs in a circle of 72 degrees diameter - at a rate somewhat under 1deg. in 72years.
more context on astronomical alignments at Giza