Page:Popular Science Monthly Volume 76.djvu/10

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6
THE POPULAR SCIENCE MONTHLY

usual custom to dismiss the entire matter as belonging to the realm of astrology or myth, especially as nothing is said regarding the system employed. This would seem, however, to be a somewhat arbitrary procedure in view of what we know of their methods and results in other problems. It is well known that by comparison of long series of eclipses, these ancient people were able to predict their occurrence by

Edmund Halley.

means of the cycle of 6,585 and one third days, or 18 years 11 and one third, or 10 and one third days, depending on whether the particular cycle included four or five leap years. It appears also, from comparatively recent investigation, that the same methods were employed in the planetary motions, and with success. It seems, then, a very natural