VOL. LXXXII.] PHILOSOPHICAL TKANSACTIONS. 127 



it was seen only of the magnitude of y Ceti nearly; or between y and S; but, as 

 bad weather has occasioned many interruptions, it may possibly have been larger. 

 The period of 333 days, assigned by Bouillaud, does not agree with present 

 observations compared to those of Fabricius made on the 13th of August, 15Q6, 

 when this star was in its greatest lustre. M. Cassini also found, that his obser- 

 vations, in the beginning of August, 1703, when the star was brightest, did 

 not agree with the interval of 333 days; and therefore, supposing the star to have 

 changed 1 17 times since the epoch of Fabricius, he gave it a period of 334 days. 

 This will however not agree with the present time of the changes; and it appears 

 now that M. Cassini ought to have assumed 1 18 instead of J 17 variations; which 

 would have pointed out a period of 33 1 days, and some hours. 



That this is probably very near the real time of the star's variation, will be 

 seen when we admit it to have undergone 214 changes between Aug. 13, i5g6, 

 and Oct. 2 1 , 179O; by which long interval we obtain the period of 33 1 days, 10 

 hours, 19 minutes. It will indeed be necessary, in order to reconcile all obser- 

 vations, to admit of some occasional deviations in the appearance of the star, 

 amounting almost to a month: besides, a period of 334 days could not be ad- 

 mitted without totally giving up all regularity in the returning appearance of 

 the star. 



On the disappearance of the 55th HercuHs. — Among the changes that happen 

 in the sidereal heavens we enumerate the loss of stars; but though the real de- 

 struction of a heavenly body may not be impossible, we have some reasons to think 

 that the disappearance of a star is probably owing to causes which are of the 

 same nature with those that act on periodical stars, when they occasion their tem- 

 porary occultations. Two stars of the 5th magnitude, whose places we find in- 

 serted in all our best catalogues, were to be seen in the neck of Hercules. They 

 are the 54th and 55th of Flamsteed's, in that constellation. In the year 1781, 

 Oct. 10, Dr. H. examined them both, and marked down their colour, red. April 

 11, 1782, he looked at them again, and noted having seen them distinctly, with 

 a power of 46O; and that they were single stars. Last May 24, he missed one 

 of the two, and examining the spot again the 25th, and many times afterwards, 

 found that one of them was not to be seen. The situation of the stars is such 

 that, not having fixed instruments, he could not well determine which of the 

 two was the lost one. He therefore requested the favour of the astronomer royal 

 to ascertain the remaining star; and it appears from Dr. Maskelyne's answer to 

 his letter, that the 35th Herculis is the one which we have lost. 



Remarkable phenomena in an eclipse of the moon. — Oct. 22, 1 7go, when the 

 moon was totally eclipsed. Dr. H. viewed the disk of it with a 20-feet reflector, 

 carrying a magnifying power of 360. In several parts of it he perceived many 

 bright, red, luminous points. Most of them were small and round. They 



