Davis, Brown & Company
Samuel Davis and Robert Johnston Brown were partners from about 1808 to 1818 and likely later. They were located on the corner of Mild and Marlboro Streets in Boston. Davis & Brown were wholesale dealers and importers, and their suppliers in England included Peter Stubs for clock movements, castings and other parts. This watch imported and sold by them in about 1815.
The movement is serial number 1000 with verge escapement and fusee. Consular case is marked 18 carat gold with Chester assay date for 1815 and case maker mark "HH" for Hannah Howard, Lombard Street, Liverpool, England.
Although hallmarked 18 carat, gold cased watches during this time period with Chester marks are known to be under 18 carat including watches that were sold by this Boston retailer. Some have faux Chester marks (and may lack a date mark), while others have full hallmarks. This example has not been tested. More study is needed in the area of substandard English and American 18K gold cases made for the American market.
HH Case Maker's Mark
Additional References and recommended reading:
Spittler and Bailey, Clockmakers and Watchmakers of America by Name and by Place, Columbia, PA., National Association of Watch and Clock Collectors, 2011