* The gradual disappearance of ships over the horizon, the tops of the sails disappearing last;
* The shape of the curved shadow of the earth on the moon during eclipses;
* The variation of the sun's elevation with latitude (this was the basis of Eratosthenes' measurement);
* The variation of a star's elevation with latitude. The fact that one sees new stars as one moves north or south on the earth's surface;
* Matter tends to form into drops or globs, and the earth, in forming from chaotic matter, did the same;
* Proof by elephants. When one travels west from Greece, one finds elephants (African). When one travels east one finds elephants (Asian).
26 March 2008
Aristotle argued for a spherical earth for these reasons: