STUDIES ON THE VARIABLES OF THE ALGOL-TYPE. 19 



solar density and liis constant is, converted into the standard 



density, 



52.2. 



Recently Stein gave the constant as follows (M. N. LXIX, 



449): 



44.0, 



which is also converted into the standard density. 



So far as I know, the density of the Algols was calculated 

 by the above four astronomers, Roberts on the four stars : Russell 

 on 17 Algols, then available for this purpose, using the data 

 from Chandler's Third Catalogue of Variable Stars and also 

 from other informations. Although André gave somewhat 

 different results for these stars, the data were used exclusively 

 according to Russell and the difference is the result from the 

 different value of the constant. Ristenpart restricted his deter- 

 mination on the stars for which Graff determined the circular 

 orbits. Stein extended his researches on the Algols for which 

 he was able to obtain the necessary data, and the number of 

 the star was 38. My work on this side were begun two years ago 

 before knowledge of Stein's work, adopting the value of constant 

 by Russell. Finally, at the close of the present investigation, I 

 w^as able to calculate the density for 74 stars, for which tore- 

 lably known data were collected. 



The formula for the calculation was 



0.0765 6 

 ^"^^l^^I^- C2.8840] 



^^ 0.07656 



r 



where the period is expressed in days and r denotes the ratio 

 between the period and the duration of the eclipse. 



