By sheer speculation Greece was well on the way of discovery.
Then the mists of philosophy fell between the mind of Greece and
nature, and the notions of Democritus were rejected with disdain;
and then, very speedily, the decay of the brilliant nation put an
end to its feverish search for truth. Greek culture passed to
Alexandria, where it met the remains of the culture of Egypt,
Babylonia, and Persia, and one more remarkable effort was made to
penetrate the outlying universe before the night of the Middle
Ages fell on the old world.
Astronomy was ardently studied at Alexandria, and was fortunately
combined with an assiduous study of mathematics. Aristarchus
(about 320-250 B.C.) calculated that the sun was 84,000,000 miles
away; a vast expansion of the solar system and, for the time, a
remarkable approach to the real figure (92,000,000) Eratosthenes
(276-196 B.C.) made an extremely good calculation of the size of
the earth, though he held it to be the centre of a small
universe. He concluded that it was a globe measuring 27,000
(instead of 23,700) miles in circumference. Posidonius (135-51
B.C.) came even nearer with a calculation that the circumference
was between 25,000 and 19,000 miles; and he made a fairly correct
estimate of the diameter, and therefore distance, of the sun.
Pages:
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30