Actually, if I recall correctly, you would have to repostion the paper by visual guesstimate, since the carriage only moved in designated steps. I remember having to do just that on old Selectrics. But why would Killian bother with such a fractional centering detail in a memo to himself, especially since he didn't type at all?
Bingo.
I actually remember from the bad old days when I had to type college papers on a real, fixed pitch, typewriter.
Centering is a bloody pain in the Rather.
You'd have to count the letters, center the carriage, then backspace half the count.
With proportional fonts, nobody but a typesetter would bother.