I 14 



Report S.A.A. Advancement of Science. 



is a succession of waves. That is the two stars which make up this, 

 system circle round one another in contact. 



In the case of X Carinae separation has taken place. The 

 component stars are nearly half the diameter of either of them 

 apart. 



It would be entirely out of place to present the s)stem of 

 equations which connect the light changes of any Algol binary 

 system, as exemplified by its light curve, with the orbital movements 

 and rragnitudes which produce them. 



FIG. 2. 



y^ 



\ 



\ \ 

 \ 



/■ 



/' 



' V ^ \ 





It will be more pertinent to the present line of inquiry to con- 

 sider one or two of the problems which have arisen out of the 

 foregoing statement of our present knowledge of close binary systems. 

 These problems I take it are of considerable interest and import- 

 ance. Some of them have already been indicated. 



(A.) It may be demonstrated, as already stated, that the varia- 

 tion of such stars as S Velorum — there is another exactly similar. 



