THE FIRST PART

This diagram demonstrates that the earth is spherical.

A series of four horizontal diagrams illustrating how the shape of the Earth would affect the shape of its shadow during a lunar eclipse.

1. The first diagram shows a round Earth casting a round shadow on the Moon. The Moon is depicted with a face on the left, and the Sun with a face on the right. The Earth in the center is labeled "NIGHT" (NOX) and "DAY" (DIES).
2. The second diagram shows a square (tetragonal) Earth casting a diamond-shaped shadow on the Moon.
3. The third diagram shows a triangular Earth casting a triangular shadow on the Moon.
4. The fourth diagram shows a hexagonal Earth casting a hexagonal shadow on the Moon.

If the earth were tetragonal, a shadow of a tetragonal figure

would also appear in a lunar eclipse.

If the earth were trigonal, the shadow would also have

a triangular form.

If the earth were of a hexagonal figure, its shadow would also appear

hexagonal in a lunar eclipse; yet it is seen to be round.