Purchased from antiquarian bookseller in Atlanta. He recalled that they came from the collection of a local university professor and thought she acquired them in the 1960s.
Condition
Unfortunately there is a 4" stress crack that has formed down from the rim. I have contacted a professional restorer (Andy Goldschmidt) and will likely get him to stabilize this and do some cosmetic restoration...the cost is nominal (under $250 including shipping).