Sheppard in his patent (#1623499) mentions that "sodium hyposulfite" can be used, but then immediately says that this compound is in name correct in the scientific sense and not the compound with the same name used by photographers which is sodium thiosulfate...
By hyposulfite, if he means salts in the archaic system where it's sulfite (SO3=) but with one less oxygen (making SO2=), then (As taken from wikipedia): "However salts containing SO2= and the corresponding acid, hyposulfurous acid (H2SO2) are not believed to exist." - then what would he have been referring to?
OK - I guess I can see it in my 1932 CRC Handbook - it has NaHSO2 and calls is sodium hyposulfite. But I think this is what is called sodium dithionite - not to be confused with sodium dithionate, Na2S206.
So why did he miss thiosulfate in the original patent. He sure listed a lot of other compounds, it seems like thiosulfate would have been something to try, and something they had at hand, too.