I don't know the history of the Whitemore model, like when, how long, and who, etc. But, I do know it is a very beautiful hammer gun with a unique top-lever, which you push upwards to open the action. They were offered in steel, and an extra cost option was Damascus.
Here's a listing for one on GA. This is a rather plain-Jane. I thought there was an e in the model name, but this seller spells it Whitmore.
http://www.gunsamerica.com/928793381...1874_10ga.htm#