ery natural and
sufficient theory. The Pythagoreans, it is true, argued that our earth
must be spherical, but why? Oh, said they, because in geometry the
sphere is the "most perfect" of all solid figures. Aristotle, being
scientific, gave better reasons for believing that the earth is
spherical or ball-shaped. He said the shadow of the earth is always
round like the shadow of a ball; and the shadow of the earth can be seen
during any eclipse of the moon; therefore, all who see that shadow on
the moon's disk know, or ought to know, that the earth is ball-shaped.
Another reason given by Aristotle is that the altitude of any star above
the horizon changes when the observer travels north or south. For
example, if at London a star appears to be 40 deg. above the northern
horizon, and at York the same star at the same instant appears 42-1/2 deg.,
it is evident that 2-1/2 deg. is the difference (increase) of altitude at
York compared with London. Such an observation shows that the road from
London to York is not over a flat, level plane, but over the curved
surface of a sphere, the arc of a circle, in fact.

Herodotus, the father of history, was a good geographer and an
experienced traveler, yet his only conception of the world was as a
flat, wide-extending surface. In Egypt he was told how Pharaoh Necho had
sent a crew of Phenicians to explore the coast of Africa by setting out
from the Red Sea, and how they sailed south till they had _the sun on
their right hand_. "Absurd!" says Herodotus, in his naive manner, "this
story I can not believe." In Egypt, as in Greece or Europe generally,
the sun rises on the left hand, and at noon casts a shadow pointing
north; whereas in South Africa the sun at noon casts a shadow pointing
south, and sunrise is therefore on the _right hand_. The honest sailors
had told the truth; they had merely "crossed the line," without knowing
it. If Herodotus had known that the world was spherical or ball-shaped,
he could easily have understood that by traveling due south the sun must
at last appear at noon to the north instead of the south. A counterpart
to the story of the Phenician sailors occurs in Pliny: he tells how some
ambassadors came to the Roman Emperor Claudius from an island in the
south of Asia, and when in Italy were much astonished to see the sun at
noon to the south, casting shadows to the north. They also wondered, he
says, to see the Great Bear and other groups of stars which had never