A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Robin Stuart
Date: 2018 Mar 13, 12:17 -0700
Correct, these are cartesian (x, y) pairs just as you describe it. Note that I was missing a minus sign in my previous post that strictly should have read:
"The three scales can be produced by plotting the curves (0, sin d ), (-k cos L, cos2L) and (k cos Z, cos2Z) for some arbitrary k,"
In the diagram you provided it looks like k is about 1/4,