None of these charts is graduated, and the horizontal and vertical lines which cross many of them represent neither parallels nor meridians.
The maritime discoveries and surveys of that age of great discoveries were laid down upon so-called " plane-charts," that is, charts having merely equidistant parallels indicated upon them, together with the equator, the tropics and polar FIG.
The latter, to which parallels in geologically similar regions in America are not unknown, is the most probable natural explanation that can be offered.
The Cretan "larnax" coffins, also, have no parallels outside the Aegean.
The sphere is then coated with plaster or whiting, and when it has been smoothed on a lathe and dried, the lines representing meridians and parallels are drawn upon it.