four antique American teaspoons maker IC

in rectangle. Is this Joseph Carman? John Chalmers? Joseph Carpenter? Am I failing to Inspire Confidence? Truly, as with many initial marks, the answer may never be known. Length 5 7/8 inches, monogrammed "M" in period script, the bowls are a bit chewed up (see fourth photo) and there is some tip wear-- priced accordingly.