The base is not of uniform thickness around its perimeter.Here is a photo of the interior surface. It does have a small punt-like, off-center bulge of glass on the interior.
This bottle base was found at an 1830's Potawatomie Catholic mission in eastern Kansas. The remaining lettering says "HAUT" and "AUTERNES." After a quick google search, it appears that it probably originally said "Haut Sauternes." Sauternes is a wine produced in the Sauternais region of France...