I should add that of course the measuring-scales that I mentioned, for latitude, magnification, NS/EW scale disproportion, etc., could be added, as part of a map, up the two vertical sides of the map, instead of on a separate ruler.

The scale for measuring longitude between adjacent meridian grid-lines could be between two meridians somewhere along the bottom of the map, or maybe all along the bottom of the map.

Adding some of those position-&-properties measurement-scales to a map would give information that a flat-map can't directly show.

Michael Ossipoff
Aprilis 13, 2020