That was part of my reasoning for bringing this up. If you Google questions like, who invented the first ratchet, or first socket set, or you can pose this question several different ways and J.J. Richardson is what you'll get. I agree Lugz that when you think in the sense of an actual socket set, Contal (pre Mossberg) I would agree was first. I like Rockets & your term "adapters" or "reducers" rather than sockets. I would agree the automobile industry brought about the need to have a set of sockets of all different sizes. Actually, when you look at Richardson's two "sockets", both of them only reduce the size of the larger gear in the ratchet (see pic). So, I think the term of "adapter or reducer" fits the bill more so than calling them sockets.
It's just a little frustrating that Richardson gets all the credit on Google searches when there where men before & after him that played a major role in the historical aspect of ratchet & socket invention. And worst of all, Contal almost always doesn't even show up or get mentioned in these searches or conversations.
