[ALES 
THALES AS ASTRONOMER 139 
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. i. 23. 
» 
sun’s diameter as l/720th part of the sun’s circle (Aristarchus 
of Samos). 
From Thales to Pythagoras. 
We are completely in the dark as to the progress of geometry 
between the times of Thales and Pythagoras. Anaximander 
(born about 611/10 b. C.) put forward some daring and original 
hypotheses in astronomy. According to him the earth is 
a short cylinder with two bases (on one of which we live) and 
of depth equal to one-third of the diameter of either base. 
It is suspended freely in the middle of the universe without 
support, being kept there in equilibrium by virtue of its 
equidistance from the extremities and from the other heavenly 
bodies all round. The sun, moon, and stars are enclosed in 
opaque rings of compressed air concentric with the earth and 
filled with fire; what we see is the fire shining through vents 
(like gas-jets, as it were). The sun’s ring is 27 or 28 times, the 
moon’s ring 19 times, as large as the earth, i.e. the sun’s 
and moon’s distances are estimated in terms (as we may 
suppose) of the radius of the circular face of the earth; the 
fixed stars and the planets are nearer to the earth than 
the sun and moon. This is the first speculation on record 
about sizes and distances. Anaximander is also said to have 
introduced the gnomon (or sun-dial with a vertical needle) 
into Greece and to have shown on it the solstices, the times, 
the seasons, and the equinox 1 (according to Herodotus 2 the 
Greeks learnt the use of the gnomon from the Babylonians). 
He is also credited, like Thales before him, with having 
constructed a sphere to represent the heavens. 3 But Anaxi 
mander has yet another claim to undying fame. He was the 
first who ventured to draw a map of the inhabited earth. 
The Egyptians had drawn maps before, but only of particular 
districts; Anaximander boldly planned out the whole world 
with ‘ the circumference of the earth and sea ’. 4 This work 
involved of course an attempt to estimate the dimensions of 
the earth, though we have no information as to his results. 
It is clear, therefore, that Anaximander was something of 
1 Euseb. Praep. Evang. x. 14. 11 (Vors. i s , p, 14. 28). 
2 Hdt. ii. 109. 3 Diog. L. ii. 2. 
4 Diog. L. 1. c.