As you can see from this patent drawing of the first typewriter, just next to the A key there’s a vertical ellipsis. What this was for is (almost certainly) elucidated by Keith Houston’s Shady Characters blog post. He has sussed out that it’s all to do with Morse code, transcription of which was a big use for the Type-Writing Machine.

Those of us in production who have bitched about authors who randomly use lower case “L” instead of 1 will note that Mr Sholes invited this trouble — though he wanted you to use Cap “I” as his machine ignored lower case.