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POPULAR SCIENCE REVIEW. 
Mr. Darwin arrives at the conclusion that the moon and earth originally 
formed part of the same body, and gradually separated into two ; the present 
order of things having arisen from the tidal effects subsequently produced 
on each other by the two portions of what had once been a single mass. 
How far this theory would have to be modified if the dynamical theory of 
the tides be substituted for the statical theory thus made the basis of Mr. 
Darwin’s reasoning, we have not yet ascertained. But it is certain that a. 
rotating fluid mass, such as the planet is in the very beginning described to 
be, would not, apart from frictional effects, assume the form described by 
Mr. Darwin. On the contrary, the longer axis would lie in a direction at 
right angles to the line joining the centres of the planet and its satellite, for 
precisely the same reason that the orbit of the moon around the earth has 
its curvature increased at the quadratures and diminished at the syzygies. 
There is an excellent explanation of this, the true theory of tide in a fric- 
tionless ocean, in Sir Edmund Beckett’s “ Astronomy without Mathematics.” 
Another was given by Sir George Airy in a paper read before the Astrono- 
mical Society, the substance of which (with the illustrations) will be found 
in the “ Popular Science Review,” vol. v. pp. 356, 357. The writer of the 
astronomical summary then described the explanation as “ a very beautiful 
geometrical proof that, contrary to generally received notions, were the tides 
to move without friction, there would always be low water under the moon.” 
Babylonian Astronomy . — In the last four numbers of the a Notices of the 
Astronomical Society,” there is an interesting paper (described as preliminary 
only) by Professor Sayce and Mr. Bosanquet, on ancient Babylonian Astro- 
nomy. We need not here consider the nature of the Babylonian calendar, 
because much space would be required duly to elucidate the subject. But 
there are some points relating to the identification of stars which may be 
noticed as apparently requiring further examination by the authors of the 
paper. It appears that the inscriptions are written in at least two languages 
— Assyrian and Accadian ; and “ everything has in consequence two names 
at least, though these are generally represented by the same character.” 
This is an obvious source of difficulty. But still more likely to mislead is 
the circumstance that “the planets frequently assume the names of stars 
in whose neighbourhood they were observed.” It will be manifest that 
extreme care must be taken in the investigation of Babylonian records of 
observations, under this perplexing system. Professor Sayce and Mr. 
Bosanquet consider only in their present paper a star called Icu or Dilgan, 
the former name being Assyrian, the latter Accadian, and signifying the 
11 messenger of light.” This star was used to determine the arrangement of 
lunar months in each year. Thus the following rule is given : u When on 
the first day of the month Nisan the star of stars (or Dilgan) and the 
moon are parallel, that year is normal ” (or has twelve months) ; “ When 
on the third day of the month Nisan the star of stars and the moon are 
parallel, that year is full ” (or has thirteen months). This inscription is 
in Accadian, the most ancient language of the inscriptions. “ It may be 
expected to belong to a time earlier than 2000 b.c.” From this rule the 
authors of the paper deduce the conclusion that Dilgan, the “ star of stars ” 
or the “ messenger of light,” is Capella. Now Capella is a very fine star, 
but unless it has diminished wondrously in lustre in recent times, it could 
