"Henry Sleeper Pearson, son of David and Elizabeth Sleeper Pearson was born at Newburyport, Massachusetts in May 1789.  He died in Portland, Maine in August 1878.  He is listed in the Portland directories from 1823, which was the first one issued, to 1875, as a mathematical instrument and watch maker.  In 1877 he is listed as a watch and nautical instrument maker with William Senter & Company of Portland."

Reference:  Smart, Charles E.   The Makers Of Surveying Instruments In America Since 1700  Troy, New York:  Regal Art Press.  1962