The lens looks a bit like a Petzval, but isn't big enough (!) to be a Petzval intended for 8x10". So I'm guessing a Portrait Rectilinear of some sort - at f:6, a 3" front lens corresponds to 18" focal length. So I'm guessing it's a 16" f:6 Portrait Rectilinear of some sort. "One careful owner"?