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simultaneously Oppolzer, the great comet computer, published his of Tempel's comet of 1866 (1866 I.), and the two were found to be practically identical. Here were two identities which could hardly be the result of chance. Researches since have added to the number of such comet-meteor associations. Professor Herschel catalogues seventy-six; and four pairs—the Leonids and Tempel's comet, the Perseids and Tuttle's comet, the Andromedes and Biela's comet, and the Lyrids and the comet of 1861 (1861 I.)—are shown in the diagram on the opposite page.

Thus are comets and meteors connected. But we know more about their connection than this simple fact of association. We know that the one becomes the other, for we have seen the process of transformation take place practically under our very eyes. Biela's comet was for many returns a well-ordered member of Jupiter's comet-family, of which family we shall have more to say in the fifth chapter. Up to 1839 it had returned with due regularity and without incident. In 1846, it again appeared on time, but thereupon proceeded to do something very strange and then unheard-of. In mid-career it split. It was first seen on November 28, and presented the appearance of the usual comet. By December 19 it had