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PROCEEDINGS OP THE AMERICAN ACADEMY 



taken from the light curves, and the time of the minimum, assuming 

 that it lies midway between them. This last column is found by add- 

 ing to the second column 10** 3.7*, or the period of the star ; add- 

 ing to this the third column, and dividing the result by two ; finally 

 subtracting the quotient from the period, 10** 3.7^. The mean of 

 this value, or 7.4, agrees closely with that given above. 



TABLE IV. — Minimum of ^ Geminorum. 



^ Lyrce. Light curves of this star were given by Argelander in 

 1842, Asti'on. Nach., xix. 397, and in 1844, De stella ^ Lyras variabili 

 disquisitio. In 1859 he gave a more complete discussion of the problem.* 

 He divided his previous observations into three periods, and derived a 

 curve from each ; concluding that they differed from each other only 

 by their accidental errors, he gave a curve representing the entire 

 series. 



Oudemans f gives a light curve from his observations, reduced to the 

 same system as that given in Argelander's second publication. This 

 differs so little from the last system of Argelander that the same curve, 

 for reduction to logarithms, has been used for both. In no case, within 

 the limits used, would the difference of the logarithms exceed one or 

 two hundredths. 



In 1870, Schonfeld gave another curve, Astron. Nach., Ixxv. 1. 

 His grades represent a smaller variation in the light than Argelander's, 

 and, like the latter, a grade is larger for the brighter stars than for the 

 fainter, as in the case of t, Geminorum. The relation of the grades to 

 the logarithms of the light is shown in Table V. The colunms have 

 the same meaning as in Table II., except that three additional columns 

 are given for the comparisons of Schonfeld. 



• De Stella /3 LyrsB variabili commentatio altera. 



t Zweijiiehrige Beobachtungen dcr nieisten jetzt bekannten veraenderlichen 

 Sterne. Verhand. Akad. Amsterdam, 1856. 



