History of Astronomy | Page 3

remarkable conjunctions of the planets, as well as plagues and famines,
floods and droughts, wars and the deaths of great rulers. Sometimes
they thought they could trace connections which might lead them to say
that a comet presaged famine, or an eclipse war.
Even if these men were sometimes led to evolve laws of cause and
effect which now seem to us absurd, let us be tolerant, and gratefully
acknowledge that these astrologers, when they suggested such
"working hypotheses," were laying the foundations of observation and
deduction.
If the ancient Chaldæans gave to the planetary conjunctions an
influence over terrestrial events, let us remember that in our own time
people have searched for connection between terrestrial conditions and
periods of unusual prevalence of sun spots; while De la Rue, Loewy,
and Balfour Stewart[1] thought they found a connection between
sun-spot displays and the planetary positions. Thus we find scientific
men, even in our own time, responsible for the belief that storms in the
Indian Ocean, the fertility of German vines, famines in India, and high
or low Nile-floods in Egypt follow the planetary positions.
And, again, the desire to foretell the weather is so laudable that we
cannot blame the ancient Greeks for announcing the influence of the
moon with as much confidence as it is affirmed in Lord Wolseley's
_Soldier's Pocket Book_.

Even if the scientific spirit of observation and deduction (astronomy)
has sometimes led to erroneous systems for predicting terrestrial events
(astrology), we owe to the old astronomer and astrologer alike the
deepest gratitude for their diligence in recording astronomical events.
For, out of the scanty records which have survived the destructive acts
of fire and flood, of monarchs and mobs, we have found much that has
helped to a fuller knowledge of the heavenly motions than was possible
without these records.
So Hipparchus, about 150 B.C., and Ptolemy a little later, were able to
use the observations of Chaldæan astrologers, as well as those of
Alexandrian astronomers, and to make some discoveries which have
helped the progress of astronomy in all ages. So, also, Mr. Cowell[2]
has examined the marks made on the baked bricks used by the
Chaldæans for recording the eclipses of 1062 B.C. and 762 B.C.; and
has thereby been enabled, in the last few years, to correct the lunar
tables of Hansen, and to find a more accurate value for the secular
acceleration of the moon's longitude and the node of her orbit than any
that could be obtained from modern observations made with
instruments of the highest precision.
So again, Mr. Hind [3] was enabled to trace back the period during
which Halley's comet has been a member of the solar system, and to
identify it in the Chinese observations of comets as far back as 12 B.C.
Cowell and Cromellin extended the date to 240 B.C. In the same way
the comet 1861.i. has been traced back in the Chinese records to 617
A.D. [4]
The theoretical views founded on Newton's great law of universal
gravitation led to the conclusion that the inclination of the earth's
equator to the plane of her orbit (the obliquity of the ecliptic) has been
diminishing slowly since prehistoric times; and this fact has been
confirmed by Egyptian and Chinese observations on the length of the
shadow of a vertical pillar, made thousands of years before the
Christian era, in summer and winter.
There are other reasons why we must be tolerant of the crude notions of
the ancients. The historian, wishing to give credit wherever it may be

due, is met by two difficulties. Firstly, only a few records of very
ancient astronomy are extant, and the authenticity of many of these is
open to doubt. Secondly, it is very difficult to divest ourselves of
present knowledge, and to appreciate the originality of thought required
to make the first beginnings.
With regard to the first point, we are generally dependent upon
histories written long after the events. The astronomy of Egyptians,
Babylonians, and Assyrians is known to us mainly through the Greek
historians, and for information about the Chinese we rely upon the
researches of travellers and missionaries in comparatively recent times.
The testimony of the Greek writers has fortunately been confirmed, and
we now have in addition a mass of facts translated from the original
sculptures, papyri, and inscribed bricks, dating back thousands of years.
In attempting to appraise the efforts of the beginners we must
remember that it was natural to look upon the earth (as all the first
astronomers did) as a circular plane, surrounded and bounded by the
heaven, which was a solid vault, or hemisphere, with its concavity
turned downwards. The stars seemed to be fixed on this vault; the
moon, and later the planets, were seen to crawl over it. It