Potters Guild
Since the time of the Pharaohs, the Masonic Order had investigated lines of force in nature and ascertained through experiential knowledge those structures demonstrating “the path of least resistance,” getting the desired result with minimal effort.
From this perspective, the eggshell was the obvious candidate to mimic.
The catenary curve on pottery chard (2650 BC) was excavated in or near 1925 in Djoser's Pyramid in Saqqara, Egypt.