A source-book of ancient history - The Search For Mecca

The Shape and the Size of the Earth 307
servations of the sea and sky, for here the evidence of the
senses, and common observation, is alone requisite. The
convexity of the sea is a further proof of this to those who
have sailed; for they cannot perceive lights at a distance
when placed at the same level as their eyes, but if raised
on high, they at once become perceptible to vision, though .
at the same time further removed.
So, when the eye is
raised, it sees what before was utterly imperceptible.
Homer speaks of this when he says.
Lifted up on the vast wave he quickly beheld afar. Odyssey v.
393-
Sailors, as they approach their destination, behold the
shore continually raising itself to their view; and objects
which had at first seemed low, begin to elevate themselves.
Our gnomons also are, among other things, evidence
of the revolution of the heavenly bodies; and common
sense at once shows us, that if the depth of the earth
were infinite, such a revolution could not take place.
Further, endeavoring to support the opinion that it is
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in accordance with natural philosophy to reckon the and the
greatest dimension of the habitable earth from east to us^ircuinwest,
he (Eratosthenes) says that, according to the laws of
navigation,
natural philosophy, the habitable earth ought to occupy a
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Eratosthe-
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greater length from east to west, than its breadth from by Strabo i.
north to south. The temperate zone, which we have 4- ^
already designated as the longest zone, is that which the
mathematicians denominate a continuous circle returning
upon itself. So that if the extent of the Atlantic Ocean
were not an obstacle, we might easily pass by sea from
Iberia to India, still keeping in the same parallel; the remaining
portion of which parallel, measured as above in
stadia, occupies more than a third of the whole circle:
since the parallel drawn through Athens, on which we