It’s an interesting arrangement that gives the Keaton Music Typewriter its distinctive look. In terms of engineering, thanks to a curved meter on the left that Keaton called the Scale Shift Handle and Scale Shift Indicator, it’s easy to control exactly where the notes and characters fall on the page. By moving the handle up or down a notch, the typewriter adjusts to print 1/24 inch in either direction. Moving one notch up or down will cause the character to fall one musical step either way.
It appears that the typed sheet music in the museum display (the 2nd image) is turned 90 degrees from the way the machine types, or perhaps it’s a different model.