80 
Proceedings of Royal Society of Edinburgh. [sess. 
The orbit of the system is therefore circular. At principal 
minimum, the star falls from its normal brightness, 10 m *05, to 
10 m, 90, that is, it loses 
0-543 
of its light. 
At secondary minimum the star falls from 10 m, 05 to 10 m T5, 
that is, the system loses 
0-088 
of its light. 
Assuming, as a first solution, 
7*1 = r 9 
equation (8) becomes 
Lji 
/2<£ — sin 
2 <j>\ 
) = 0-543 
\ 7T 
) 
L 2 i 
/’2<jy - sin 
2 <f>\ 
( = 0-088 
\ 7T 
) 
+ L 2 
= 1* 
L 1 = 
0-860 
L 2 = 0-140 
e£ = 72°-53' 46". 
From equation (7) 
cos l = 
O^M^ 
9219 
43'. 
vs 
0-995 
Since 
K _ 2 h 1 5 m x 360° _ 1 g 0 10 , 
44 h 30 m 
then from equation (9) 
2 r= JO-1057 = 0-325 
r = 0-163 . 
The foregoing determination of some of the principal elements 
of the binary star C.P.D. - 41°*4511 enables us to arrive at a value 
of the density of the system. 
In the Astrophysical Journal , vol. x. Ho. 5, I pointed out that 
a very simple relation existed between the orbital elements of an 
Algol system and the mean density of the system. 
