I know how it works, I know, sort of, what lens is in it. I just don't have any idea who made it, when or where it was made and what camera it might have come from. The lens is, I believe, a Rapid Rectilinear, or Aplanatnot knowing where it came from makes that distinction tough to guesstwo cemented, symetrical doublets. It covers 5 x 7 (I shot two sheets with it set for infinity), maybe more. The focal length seems to be (WAG measurement) between 170 and 190mm, so about 7 in. It's on and old(ish) Masonite board, obviously not it's original home, but I'm showing the back to indicate the rather odd mounting holes. I've taken it off the board, and these are the only holes in the mount- no regular flange. It appears to have been mounted originally on a specific front standard. I can't find anything like it on the web. Any idea?