Unidentified Boatswain?

Date:
1860s
Creator:
C. Marmu
Seated portrait of an unidentified boatswain?. He is wearing his uniform coat as well as light trousers and shirt. Insignia confusing as to rating.
Description (physical):
8x11
Location:
301 East Pratt Street Baltimore, Maryland 21201
Identifier:
LMP1.49
Institution:
USS Constellation Museum