History of Astronomy | Page 4

was a great
step to look on the vault as a hollow sphere carrying the sun too. It
must have been difficult to believe that at midday the stars are shining
as brightly in the blue sky as they do at night. It must have been
difficult to explain how the sun, having set in the west, could get back
to rise in the east without being seen if it was always the same sun. It
was a great step to suppose the earth to be spherical, and to ascribe the
diurnal motions to its rotation. Probably the greatest step ever made in
astronomical theory was the placing of the sun, moon, and planets at
different distances from the earth instead of having them stuck on the
vault of heaven. It was a transition from "flatland" to a space of three
dimensions.
Great progress was made when systematic observations began, such as
following the motion of the moon and planets among the stars, and the
inferred motion of the sun among the stars, by observing their _heliacal
risings_--i.e., the times of year when a star would first be seen to rise at

sunrise, and when it could last be seen to rise at sunset. The grouping of
the stars into constellations and recording their places was a useful
observation. The theoretical prediction of eclipses of the sun and moon,
and of the motions of the planets among the stars, became later the
highest goal in astronomy.
To not one of the above important steps in the progress of astronomy
can we assign the author with certainty. Probably many of them were
independently taken by Chinese, Indian, Persian, Tartar, Egyptian,
Babylonian, Assyrian, Phoenician, and Greek astronomers. And we
have not a particle of information about the discoveries, which may
have been great, by other peoples--by the Druids, the Mexicans, and the
Peruvians, for example.
We do know this, that all nations required to have a calendar. The solar
year, the lunar month, and the day were the units, and it is owing to
their incommensurability that we find so many calendars proposed and
in use at different times. The only object to be attained by comparing
the chronologies of ancient races is to fix the actual dates of
observations recorded, and this is not a part of a history of astronomy.
In conclusion, let us bear in mind the limited point of view of the
ancients when we try to estimate their merit. Let us remember that the
first astronomy was of two dimensions; the second astronomy was of
three dimensions, but still purely geometrical. Since Kepler's day we
have had a dynamical astronomy.
FOOTNOTES:
[1] Trans. R. S. E., xxiii. 1864, p. 499, On Sun Spots, etc., by B.
Stewart. Also Trans. R. S. 1860-70. Also Prof. Ernest Brown, in _R. A.
S. Monthly Notices_, 1900.
[2] _R. A. S. Monthly Notices_, Sup.; 1905.
[Illustration: CHALDÆAN BAKED BRICK OR TABLET, Obverse
and reverse sides, Containing record of solar eclipse, 1062 B.C., used
lately by Cowell for rendering the lunar theory more accurate than was

possible by finest modern observations. (British Museum collection,
No. 35908.)]
[3] _R. A. S. Monthly Notices_, vol. x., p. 65.
[4] R. S. E. Proc., vol. x., 1880.

2. ANCIENT ASTRONOMY--THE CHINESE AND CHALDÆANS.
The last section must have made clear the difficulties the way of
assigning to the ancient nations their proper place in the development
of primitive notions about astronomy. The fact that some alleged
observations date back to a period before the Chinese had invented the
art of writing leads immediately to the question how far tradition can be
trusted.
Our first detailed knowledge was gathered in the far East by travellers,
and by the Jesuit priests, and was published in the eighteenth century.
The Asiatic Society of Bengal contributed translations of Brahmin
literature. The two principal sources of knowledge about Chinese
astronomy were supplied, first by Father Souciet, who in 1729
published _Observations Astronomical, Geographical, Chronological,
and Physical_, drawn from ancient Chinese books; and later by Father
Moyriac-de-Mailla, who in 1777-1785 published _Annals of the
Chinese Empire, translated from Tong-Kien-Kang-Mou_.
Bailly, in his Astronomie Ancienne (1781), drew, from these and other
sources, the conclusion that all we know of the astronomical learning of
the Chinese, Indians, Chaldæans, Assyrians, and Egyptians is but the
remnant of a far more complete astronomy of which no trace can be
found.
Delambre, in his _Histoire de l'Astronomie Ancienne_ (1817), ridicules
the opinion of Bailly, and considers that the progress made by all of
these nations is insignificant.
It will be well now to give an idea of some of the astronomy of the

ancients not yet entirely discredited. China and Babylon may be taken
as typical examples.
China.--It would appear that Fohi, the first emperor, reigned about
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