^ The earliest showing I have of that monstrous A2285 5/8" square female drive model is in that catalog from 1932 - the same year that AA says the 1/2" square female drive model 916 was issued.
I posted the photo of the A2285 because it appears to be very similar in design to the 916 model posted above by Targa68.
Purely wild speculation on my part, but considering the number of patents issued to Warren S. Bellows, and the number of times his name appears on datamp.org pages at lower left under "witnesses", I'm inclined to think that he applied for or was issued a patent on that 916.
If NOT, is it using the same internals as those earlier two?
I tend to doubt that.
And yes, it would be most interesting to see exactly what's inside that thing.