Page:Popular Science Monthly Volume 76.djvu/20

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extended for three or four weeks, and were made at Ingolstadt. Apian first established the fact that the comet's tail is constantly directed away from the sun. This was the first substantial item of evidence towards showing that comets, instead of being simply terrestrial phenomena, are in some way connected with the cosmic universe. The system of Copernicus had not then appeared, so the true solution of the problem could not be expected, though here at least was a beginning. Earthquakes, showers of blood and fiery appearances in the heavens are charged to this comet, but from now on, we have less and less of these matters. The next appearance, 1607, was detected by Kepler, though it had been seen a few days before by a monk in Swabia. Kepler furnishes a series of observations from September 26 to October 26, but he was less fortunate in his speculations regarding its nature and movements than had been his lot in his planetary researches.

The year 1682 brings us again to Halley. In these attempts to identify the early appearances, the Chinese annals have been of great assistance. In some cases all of the substantial evidence which we possess comes from this source. These records were kept in a much more systematic manner than the chronicles of the western people. The times when the comet was first and last seen are carefully recorded. The path, observed among the stars, is often given, not, of course, with extreme accuracy, but sufficiently so as to admit of the determination of an approximate orbit, and thus furnish valuable data for identification. The Chinese appear not to have been disturbed by the superstitious dread of comets which pervaded Europe. Their accounts of the physical characteristics are unsatisfactory, the length of tail and similar matters being given, not in angular, but in linear, measure, which, of course, means nothing.