The Flagler Museum in Palm Beach, Fla., is lining its domed music room with newly restored seating that had long been shedding bits of gilding and threads from its tapestry upholstery. Meanwhile, the once-prominent original supplier of the furniture, Pottier & Stymus, is re-emerging from obscurity.

The oil and railroad magnate Henry Flagler and his third wife, Mary Lily Flagler, bought roomfuls of Pottier & Stymus furnishings around 1902, as Mr. Flagler’s longtime favorite architecture firm, Carrère & Hastings, was completing construction of the couple’s showplace Beaux-Arts house.