The fixed stars are liable to changes; several stars observed in former times by the ancients, are now no longer seen, and new ones have appeared, unknown to the ancients. Some of them have disappeared for a time, and then become again visible. Some have been observed to increase in superlative lustre; then decreasing, have, by degrees, vanished from the sight even of the best telescope.

Hipparchus observing an unknown star, in order that posterity should learn whether any of the stars perish, composed a catalogue of the stars. Tyeho Brake, after several ages, observed another new star, and in the philosophical transactions, we have accounts of several.

The first new star in the chair of Cassiopeia was not seen by Cornelius Gemmo, on the 8th of November 1572, although he that night considered the heavens in a very serene sky, and saw it not; but the next night it appeared, with a splendour surpassing all the fixed stars, and scarcely less bright than Venus. Tycho Brahe observed it on the 11th of the month; but from thence he assures us, that it gradually decreased and died away, so that in March 1574, after sixteen months, it was no longer visible, and at this day no signs of it remain.

September 30, O. S. 1604, such another star was seen and observed by the scholars of Kepler, in the constellation Serpentarius. It broke out at once with a lustre surpassing that of Jupiter; and like the former, in nearly the same time, died away gradually, and of this, there are no footsteps to be now seen.

Between these, in 1596, we have the first account of the wonderful star in Collo Ceti, seen by Fabricius on the 3rd of August, as bright as a star of the 3rd magnitude, which has been since found to appear and disappear periodically. Its period being precisely seven revolutions in six years, though it returns not always with the nine lustre, nor is it ever totally extinguished, hot may at all times be seen with a six feet tube Another new star was discovered by Hevelius, July 15, 1600, as a star of the third magnitude, hot so waned in lustre, that by the beginning of October it was scarce to be seen. In April following, it was brighter than before, yet wholly disappeared about the middle of August. The next year in March 1602, it Was seen again, but not exceeding the sixth magni-tode; since then, it has been no further visible, though fre-quently sought after by Astronomers.

Mr. G. Kirch in 1686 discovered another, whose period was 404½ days. In August this star is visible to the naked eye, but in December scarcely to be seen. It is brightest in the month -of September. Independently of these, may be mentioned a 'star, well known to Astrologers, Caput Algol, a variable star; its period is 2 days 21 hours. It remains for 2 days 14 hours, as a star of the second magnitude; in about three hours and a half it declines to a star of the fourth magnitude; and in three hours and a half more, it resumes its second magnitude, which it retains for 2 days 14 hours, as before. 8 in Lyra likewise has a period of 12 days 19 hours, during which time it appears of different magnitudes, from the third to the fifth; in Anti-nous, has a period of 7d. Ah. 38m.; and ) in Cepheus, of 5d. 8h. 37m. 'No doubt all these changes have a manifest effect on the earth, which may probably produce some of those strange • vicissitudes that baffle the wisest to determine, and for which, even the Astrologer may be at a loss to account.