Protos are a requirement for patent?
I'm not sure of that, I believe at least a working model is needed for most patents. Those listed as design patents apparently are different and I'm not sure exactly what they are, the one linked to above, D0142522 for the frame, states that the description goes with the "accompanying drawing" so it appears it only required a drawing.
Doing a quick history check...
*) A design patent is a patent for any article that can be manufactured - as opposed to a utility patent which covers processes, etc. There's now also patents for plants, probably animals, etc..
*) All patents up to 1880 had to have a small model submitted with the patent. it didn't have to work, but it had to show the patented invention.
--) Discontinued in 1880 due to lack of space and fire hazard (many old models were lost in a couple of fires that had broken out in the model storage areas).
*) From 1871 onwards, drawings had to be submitted.
I can't find any mention of working prototypes ever being required, though there were 2 year time limits on patents submitted by foreign nationals in regards to the patents being used or becoming voided. Another possible reason that Arthur might have assigned his early patents over to others even before he was employed by a company. They may have bankrolled him in exchange for ownership of his patents, or it was a workaround to avoid the 2 year limitation.
So drawings had to be submitted, but prototypes didn't have to exist. It doesn't mean that prototypes couldn't exist.. obviously Savage did build prototypes of many (most?) of their patents.
