( 471 ) 



The minimum or maximum of light takes place when q takes 

 "extreme" values, consequently when 



— =. cos V sin V sin^i -f- e sin u = (2) 



dv 



In formula (2) sin t; = for the principal minimum, easy :^ — -. 



sin^i 



for the "secondary maximum". This is in the assumption that the 



time of the principal minimum coincides with the time of periastron. 



Therefore if, at the moment of the maximum, we know e and v, 



then we know also i. Terkan adopts the value 0.07, derived for e 



by Belopolsky from his spectroscopic observations^). He determines 



the mean anomaly at the maximum from the interval found by 



Plassmann *) : 



II min. — II max. = 3,05 days, 



and then expands this anomaly in a series ^) by the aid of 



e 

 cos V =^ ] — ;. This series has an argument «, which contains smh. 



sin^i 



He thus finds 



i=5V.S. 



Afterwards, in his Hungarian paper ^), he takes e = 0.06. From his 



own observations he derives: I min. — I max. =r 3,48 days and then 



e 



finds, using the usual equations of Kepler, by the aid of cosv =^ ^ — ; : 



sin^i 



i=i30°. 



Even if we disregard the very doubtful value of the numerical 

 data, the hypothesis seems unfounded that the maximum of the light 

 occurs at the moment that ^ is a maximum. If, moreover, we assume 

 with Dr. Terkan, both the celestial bodies to be spherical, then the 

 light must be constant as long as the two spheres do not cover each 

 other as seen by the observer. This is not confirmed by observation. 

 Besides there can be no question of a clearly defined epoch of 

 maximum in such a case. The way in which Dr. Terkan meets this 

 objection by saying: "that our eye or the telescope is unable to 

 separate the system and that the rays of light which^ in space come 



») See p. 462. !«* footnote. 



') A. N. nr 3242. 



^) ' In this series e has been erroneously substituted for sin <p cos <p and 



— (instead of / — - — for tg (45°— i^). 



■*) (3 Lyrae palyaelemeinek etc. p. 412. 



