OF ARTS AND SCIENCES. 273 



7} Geminorum. — These observations precede by seventy years those 

 taken elsewhere. They will therefore have great value in determin- 

 ing the period when the nature of the variations is more accurately 

 established. The small change in light, however, makes the result 

 derived from any small number of observations somewhat doubtful. 



^ Geminorum. — A comparison of the results obtained by Arge- 

 lander* with the photometric measures gives the variation in light of 

 this star from 3.6 to 4.2. It was therefore apparently observed by 

 Herschel near its minimum. The light curve indicates that the obser- 

 vation preceded or followed a minimum by about nineteen hours, but 

 the chanee in brightness durijij; this time is much less than the uncer- 

 tainty of the observation. The ephemeris of Schonfeld indicates a 

 minimum for Ep. — 2434 at 1795, Nov. 8*^ 5*^.6, which does not differ 

 from the time of observation by as much as the uncertainty of the 

 comparison. 



8 Cephei. — According to the curve of Argelander,t this star has 

 the magnitudes of 3.5 and 4.3 at maximum and minimum. The obser- 

 vation of Herschel would correspond to 8.0 grades. This indicates a 

 minimum preceding it by 1'^ 2^ or 2'^ 20'', according as the light was 

 increasing or decreasing. The star is above the horizon nearly all 

 night, hence the time of observation is fixed only by the limits of twi- 

 light. We may therefore call the time of observation, 179G, Nov. 

 5^ 12'' ± G*". The elements of Schonfield give for Ep. — 2987 a 

 minimum at 1796, Nov. 4*^ 7'' 24"\ which agrees as well as could be 

 desired with the observation. As in the case of t} Aquilce, the obser- 

 vations of contemporaneous observers fix the period of this star so 

 accurately that a correction based upon a small number of observa- 

 tions does not seem justifiable. 



yS Lyr(£. — The variations of this star have been so thoroughly de- 

 termined by other observers that these observations cannot add much 

 to our knowledge of the subject. Only one observation, No. 28 

 of Table L, is sufficiently precise to be of value, and the interval 

 hei'e employed — , is too large to be estimated with accuracy. This 

 observation has therefore not been reduced. 



R Lyres. — The variations of this star are so small that it is doubt- 

 ful if the observations of Herschel can be utilized. 



p Persei. — The same remark may be applied to this star as to 

 g Ilerculis. 



X Tauri. — This star belongs to the Algol class. The maximum 



* Bonn Beob., vii. 389. t Astron. Nach., xix. 39-3. 



VOL. XIX. (n. S. XI.) 18 



