What is the history of 1840 Parker double barrel shotgun?

To answer your question quickly,the answer is none.Parker Bros.began production of there shotguns in the year 1866.They continued production until 1934 when Remington took over production and then moved the plant to Ilion,New York in 1938.While you mave have a shotgun dated to 1840,this would not be a Parker Brothers shotgun.