Thanks, nycellist!

Just one note: what he calls "bow angle" is not perpendicularity (or non-perpendicularity) between the bow and the string; rather, it is what we often call "bow plane" (as in "your bow is in one plane playing an open CG double-stop, and in a different plane when playing an open GD double-stop'). The article might be a bit confusing unless you realize that.