The Becker Hand is one of the longest-running hand-shape prosthetic products around, and has been well described by Wolf Schweitzer in this post. I have been trying one out, thanks to John Becker, who is still in the family business, and plan to do a more detailed evaluation of this very cool old technology.
As I was doing some patent research, I came across this patent, issued to a Mr. William McElroy, for a hand which I think you'll agree bears a striking resemblance to the Becker hand (externally, at least).
I hadn't heard of McElroy before, but he patented some interesting things, including this hook. Here's the first Becker patent, filed six months after McElroy, and issued to Edward Laherty three years after McElroy's patent. Laherty assigned 49% to Becker.
By 1938, when Becker's second patent was filed, his hand looks very much like the Becker Mechanical Hand that is still sold today.
As with some of the other figures involved in prosthetic arms last century, it would be interesting to understand some of these relationships, beyond the suggestions that we get from patent records.