Large, single-reeded circular dish with hammered booge and flat well; no foot ring. Underside struck with the incuse serif letters "A" and "M", two partial "SEMPER EADEM" touch marks of John Skinner, and a very faint "[LO]NDON" in raised serif letters in a scrolled reserve.
Maker is John Skinner (1733-1813) of Boston, MA; working 1756-1785 or 1790. A succession of Boston pewterers used the "Semper Eadem" touch mark and "London" banner.