VOL. VI.] PHILOSOPHICAL TRANSACTIONS. ' fiOQ 



it scarce appeared of the fourth magnitude. In the night of August 10, it wag 

 only of the fifth. And it has ever since decreased still more, so that at last it 

 became so small that it could no more be seen. 



And so it has remained for six months without showing itself, till March 17 

 last, when Dom. Anthelme spied it in the very same place where it was the 

 year before, and found that it was of the fourth magnitude. The assembly that 

 meets in the king's library having notice thereof, several of them observed this 

 star the 2d of April last, and found it in the same place where they had seen it 

 the last year. The 3d of the same month M. Cassini found it greater than the 

 two stars of the third magnitude that are below in the constellation of Lyra, but 

 a little smaller than that in the beak of Cygnus. The 4th of the same month, 

 it appeared to him almost as large and much more radiant than that of the beak 

 of the Swan. On the Qth he found it a little diminished, and almost equal to 

 the greater of the two stars that are below in Lyra. On the 1 2th it was equal to 

 the least of these two stars. On the 15 th he perceived that it increased, and 

 was equal the second time to the greater of these two stars. From the l6th to 

 the 27th it appeared of different magnitudes, being sometimes equal to the 

 larger of these two stars, sometimes equal to the smaller, and now and then be- 

 tween both. But the 27th and 28th it was become as large as the star in the 

 Swan's beak. The 30th it appeared a little clearer. And the first six days in 

 May it was greater. The 15 th of May it was seen smaller than the same star. 

 The 1 6th, it was in bigness between the two stars that are below in Lyra ; and 

 ever since it has diminished. 



Thus this star has been twice in its greatest splendour: first on the 4th of 

 April, and the second time in the beginning of May : which we read not to have 

 ever happened to any other star. As far as can be judged, from the few obser- 

 vations made of this star, it is likely it is returning about ten months to the 

 same appearance; whereas that in the Whale's neck makes its revolution in ele- 

 ven months. As for the star in the Swan's breast, we have as yet no certain 

 knowledge of the period of its revolution; yet we may be assured that it takes 

 not less than 14 years to finish it. 



The discoveries that have been made in the heavens this last age show, that 

 changes are not so rare there as formerly was believed. If that was true what 

 Pliny says, that Hipparchus, on the occasion of a new star he perceived, made 

 an enumeration of all those which appeared at that time, there would not be 

 any one constellation in which some change were not found since that time, 

 since there are few wherein there be not found more stars now than that astro- 

 nomer has noted in them. But as the little assurance we have of the exactness 

 of Hipparchus's catalogue, gives reason to believe, that many stars which were 



VOL. I. 4 H 



