Page:The fairy tales of science.djvu/247

Rh with the Comets seen in 1105 and 575, and also with that seen in 44 or 43 B.C., of which mention has already been made.

Another great Comet—the one which, as I have told you, frightened poor Charles V. in 1566, and is expected to reappear in 1860—is held to be identical with certain comets observed in 104, 683, 975, and 1264, to which latter attaches the reputation of having presaged the death of Pope Urban IV., who died on the 2nd October, just when that Comet was making its last appearance in the heavens.

Another, again, which appeared in 1661, is supposed to be the same as that seen in 243, 891, 1145, 1402, and 1532.

The Comet discovered by Olbers, in 1815, in the constellation Musca, has a period of 74 years. Some of our family revolve in comparatively short periods round the sun. One of the most remarkable of these is the one called Encke’s Comet—so named from Professor Encke, of Berlin, who first ascertained its periodical return. This Comet revolves round the sun in the short period of $3 1⁄3$ years; it has been observed in 1786, 1795, 1805, 1818, and regularly ever after, there being, however, a very strange and anomalous circumstance connected with it—viz., that its periods of revolution are found to be successively and equably shorter, a circumstance which forebodes its ultimate fall into the sun, unless it should previously be dissipated altogether—a termination of its career by no means