The quill whizzed across the parchment between them, back and forward as though it were skating.
I've never seen "back and forward" before. I doubt if it means the same as "back and forth". Is there any difference between these two phrases?
The phrases "back and forth" and "backward and forward" mean basically the same thing. The phrase "back and forward" seems to be an inconsistent combination of the two phrases. This particular phraseology may have been unintentional, as this seems to be the only time in the seven books that the author used it. Throughout the rest of the books, "backward and forward" is used approximately 27 times and "back and forth" is used once.