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.
3) both parallels and meridians are curved.
The latter, to which parallels in geologically similar regions in America are not unknown, is the most probable natural explanation that can be offered.
For archaeological parallels one may compare the tombs of Rekhmire (15th cent.