I’ll put my money on Gene.
Don't... I shared the link with a couple people sometime ago trying to figure this one out but we could not find anything. I have copies of patents for quite few sights on my computer and I could not find anything that looked like it. I know if I would have seen a patent for something like that I would have saved a copy but when a looked for patents several years ago I only went to 1946, so there might be a patent. The use of the term "patent pending' does not even require having filed for one yet. Now that I know a possible date range I might be able to find something.
My thoughts on the adjustment were that the circular part looked like it is in a spring base and that there must be an eccentric on the bottom to change elevation as it is turned, just a guess though.
