While looking up something today, I got lost in the dictionary (an almost daily occurrence around here). I ended up finding out that scale in the sense of “a calibrated line” (etc.) isn’t related at all to scale from a fish or dragon, or scale “an instrument for weighing”.
Fishy or judicial scale comes from PIE *skel- “to cut” and is cognate with shell, shale, scalp, skill, shelf, etc.
Calibrated scale comes from Latin scalae “flight of steps; ladder”, and ultimately from PIE *skand “to jump, climb”, so it’s cognate with the –scend in descend, ascend (etc.) but also scan, scandal, slander, and echelon. Watkins (in the AHD) says the –nd– assimilates to a following suffix –slā– to form scalae and its derivatives.
I found all that out, and more besides, but I’m not sure if I found what I was originally looking for. Now I can’t remember what it was.
