Don,
I know of only one other Langenhan like the one on the Beeman collection, and fortunately on this one the Langenhan name was clearly visible, so it was possible to make a positive ID.
Another version is known, also marked Langenhan, which has a cast steel rather than wooden frame, with a shape very reminiscent of the Quackenbush/ Bedford & Walker/Champion pistols of the late 1800’s. It presumably dates from similar period.
Unfortunately the Langenhan origin of the wood grip Beeman pistol was not known when the second edition of the Encyclopedia of Spring Air Pistols was published, and in there it was only briefly mentioned, wrongly assuming it to be a modified EG TB pistol.