STUDIES ON THE VARIABLES OF THE ALGOL-TYPE. 5 



fitable for us to remember the cause of tlie class of variables. 

 It is well known fact that Algol is the phenomenon produced by 

 a companion around the principal star w^iose orbital plane passes 

 through the solar system or very near it. Then theoretically 

 considered, eclipsing variables are not confined in Algol types only. 

 Keally, for the stars belonging to the ß Lyrae type, the cause 

 is pretty fairly established from the spectroscopical considera- 

 tions. Still, at present, the classifications divides these stars 

 into two different types ; tbe one, being the Algol and the other, 

 the variable of short period. 



At the first meeting in 1903 of the South African Associa- 

 tion for the advancement of Science, A. W. Roberts presented 

 a paper concerning the eclipsing star and in it, he arrived at 

 the conclusion that S Verolum, one which shows the stationary 

 minimum during some interval ; R Arae, an ordinary Algol-type 

 variable ; KR Veloruin showing a secondary minimum ; X 

 Carinae, having an intermediate state between the Algol-type 

 and C Geminorum-type as Avell as RR Centauri of the type of 

 C Geminorum or of the type of ß Lyrae belong to the eclipsing 

 star. 



But if we should classify the variable stars according to the 

 commonly adopted standards, it would be difficult to include the 

 stars like RR Centauri in the Algol-type. And if we do so, we 

 shall have much trouble to distinguish such stars from the 

 variables belonging to the type of the short period. Thus, the 

 cause of the phenomena might not be the foundation of the 

 classification, in the present state of things, although the Algols 

 will possibly be explained by the eclipse theory in all of them. 

 Previously, the Algols w^re confined for the variables whose 

 period does not exceed over ten days, but recently the length of 



