Cosmographia Petri Apiani, per Gemmam Frisium ... iam demum ab omnibus vindicata mendis, ac nonnullis quoque locis aucta ...

A diagram shows four rows of celestial bodies (Sun, Earth, Moon) illustrating how the shape of the Earth affects the shape of the lunar eclipse shadow. The first row shows a spherical Earth casting a round shadow. The second row shows a square Earth casting a square shadow. The third row shows a triangular Earth casting a triangular shadow. The fourth row shows a hexagonal Earth casting a hexagonal shadow.

If the earth were square, the shadow also would appear as a square figure in a lunar eclipse.

If the earth were triangular, the shadow would also have a triangular form.

If the earth were of a hexagonal figure, its shadow also in a lunar eclipse would appear hexagonal, which, however, is observed to be round.