168 SPECIAL RESULTS IN THE URANOLOGICAL PORTION 



shew, that in longer intervals of time small fluctuations 

 occur ; not, however, exceeding about 20 seconds. The 

 change of light even proceeds with so much regularity, that 

 hitherto no deviations have been perceptible which may 

 not be explained by errors of observation. At its minimum 

 this star is a gradation fainter than t Aquilae ; it then 

 increases, at first slowly, then more rapidly, and then 

 more slowly ; and 2d. 9h. after the minimum it attains its 

 greatest brightness, when it is almost three gradations 

 brighter than /3,but still 2 gradations fainter than 3 Aquilae. 

 The decrease from the maximum is less regular, for when 

 the star has declined to the brightness of /3, which it 

 reaches 1 day and 10 hours after the maximum, it alters 

 more slowly than before or afterwards. 



7. Lyra, K. A. 281 8', Decl.-f 33 11'; a remark- 

 able star, in having two maxima and two minima. At its 

 lowest minimum it is Jrd of a gradation fainter than 

 Lyrse ; it then rises in 3d. 5h. to its first maximum, in 

 which it continues to be f ths of a gradation fainter than 

 y Lyrse. It then sinks in 3d. 3h. to its secondary mi- 

 nimum, in which its brightness exceeds that of by 5 

 gradations. After 3d. 2h. more, it reaches its second 

 maximum, when it has again the same brightness as in the 

 first, and then sinks again in 3d. 12h. to its lowest mi- 

 nimum ; so that it passes through its whole variation of 

 light in 12d. 21h. 46m. 40s. This duration, however, 

 only holds good for the years 1840 to ]844 : before that 

 time the period was less; in 1784 by 2J hours, in 1817 

 and 1818 by more than an hour, and now there is 

 evidently again a shortening of the period. No doubt, 

 therefore, it will be possible, in the case of this star also, 



