This is a U.S. Navy enlisted sailor's uniform that is currently on display in the museum's Age of Sail gallery. The coat is called a shell jacket, which was a common military uniform item for land and sea forces. This particular coat dates to 1852. U.S. Navy uniforms like this are quite rare and it is thought that this jacket is one of only about five that have survived. The buttons on the jacket have an eagle holding a fouled anchor, which was the common emblem of American sea service uniforms.
U.S. Navy enlisted uniforms in the early 19th century lacked formal standards, so there were some minor differences from ship to ship. However, sailors generally wore a shell jacket or equivalent type coat, a white shirt, and either blue or white trousers. Rear Admiral George Preble, who did invaluable work in retirement as a historian for the Navy in the 1880s, wrote this about Navy uniforms: "Previous to 1830, and I believe some little time after, the sailors wore red waistcoats when in their mustering suit. A neat pair of stockings and light pumps completed his full-dress costume. The sailor's uniform in 1835-39 was a blue cloth jacket and trousers and a white shirt, with a large blue nankeen collar and front, trimmed with rows of white tape. White trousers were worn in warm weather. His head was protected by a tarpaulin or hat of white sennit."
Shown here is an engraving of George Brown, a boatswain's mate aboard the frigate USS Columbia in the 1840s. It is frequently used by historians to illustrate the enlisted sailor's uniform during this time period.