Forehand and Wadsworth made revolvers from about 1871 to 1890. It should be a Forehand and Wadsworth, Indian model, pretty much the same as the British bulldog. I suspect the picture is a bulldog. Heres a link to a detailed picture of a British Bulldog. http://collectableweapons.com/Listings/info.php?id=91

Its seems that these were cheaply made revolvers and dont hold a ton of value. Although I would never sell if it was my grandfathers.