I got this lens on Ebay. It is acting like a Petzval, but doesn't cover 8x10 well. It should be a nice lens for a digital 4x5 camera later. It is not very sharp but is full of soul. On the lens it says A.T. Thompson & Co Lens Boston, and France. It should be a magic lantern lens and made by Darlot in France. It is hard to find information about it. But I'd expect it to be from the late 1800's.
Founder of LargeSense, the maker of large format digital cameras and backs.