Thomas A. Fine, writing at Sentence Spacing:
So I was on twitter last month when Marcin Wichary asked “Any ideas on what this key/glyph was for in the early Sholes Glidden typewriter?”
This image is from a U.S. patent, applied for before the typewriter went to market, but it was definitely there on the first models.
It’s a fascinating piece of research, and I didn’t want to spoil it here. So I’d recommend reading the full piece, to see what the mysterious ⫶ character was used for.