NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2017 Jan 1, 11:54 -0800
David P, you asked:
"Do the points along them actually mean anything, or are the curves there just to indicate which latitude the yellow circles represent? "
They represent the influence of a refractive medium with refractive index n(r) within the cylinder deflecting thr rays out towards the perimeter in the general Mercator projection.
Ha ha ha ha. :) No, as you guessed, the curves simply provide a visual indication of the way in which the projected lines differ from the pure perspective cylindrical projection. But if you had to explain it to someone, you could say that it's "as if the rays are refracted outward by some medium in the cylinder that is less dense along the axis of the cylinder and more dense near the walls" --with a heavy emphasis on the words "as if"!
By the way, I would have answered this question in my previous reply, but we were posting at exactly the same time (within a minute).
Frank Reed
