1 ET. XX. PHÆNOMENA OF THE FIXED STARS. 341

But of all the phænomena of nature, the sud-den appearance of new stars, and the disappear-ance of old ones, is one of the most singular,and difficult to be accounted for. A circum-stance of this kind first led Hipparchus to com-pose his catalogue of the stars, in order that pos-terity might be apprized of the true state of theheavens at that period; and since his time manychanges of the fame nature have been observed,both by ancient and modern astronomers. Someof the larger stars have not the fame precisesituations which are attributed to them by theancients, and others are found to have a perio-dical increase and decrease of magnitude. Thebright stars, Sirius and Arcturus, have been ob-served to change their places, by moving to-wards the south, about two or three minutes ofa degree in a century; and the stars, Aldebaranand Aquila, have also a like motion, but some-thing flower, and less easy to be determined.

Among the new stars which have been disco-vered by the moderns, that which appeared onthe 8th of November, in the year 1572, was themost remarkable. Its splendor exceeded that ofJupiter when nearest the earth, and was suchthat it could be seen in the day-time. CorneliusGemma first observed it in that part of the hea-vens which is called Castiopeia’s Chair, forminga perfect rhombus with the three stars «, ( 3 ,and y, of that constellation ; ^nd Tycho Brake,

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