I'm slowly reading through a book called the "History of Mathematical Notations" by Florian Cajori and it sounds like just what you're looking for. It goes int

I'm slowly reading through a book called the "History of Mathematical Notations" by Florian Cajori and it sounds like just what you're looking for. It goes into far more detail than probably anybody would wish for on the histories of various symbols and ways of writing addition, roots, ratios etc. Many of these notations were used only by a few medieval scholars for a few decades but they usually try to optimize for efficiency or clarity in some creative way. Really fascinating stuff.