Variation of tJie Star C.P.D. - 41°-451]. 41 



as observation makes us acquainted with, we are limited in two 

 directions. 



(1) We must apply to all facts that come within the range of our 

 knowledge only such explanations as are rational and intelligible, 

 and which are warranted by our experience of that which is more 

 immediate. 



(2) The explanations preferred must be applicable to, and sufficient 

 for, all the phenomena of a well-defined class or type. 



If the theory fails in any one single instance it is inferior, as an 

 explanation, to that which meets every case. 



Judged by these criteria, the meteoric theory of stellar variation 

 fails. 



Far more sufficient, valid, and intelligible is the theory which 

 regards variable stars as the first stage in that long spiral evolution 

 of stellar systems which, starting with contiguous homogeneous 

 gaseous bodies, ends in such binary systems as Alpha, Centauri, and 

 Castor. 



The successive stages of stellar development thus form a unified,, 

 orderly, related sequence. 



In the early stages we have contiguous bodies of gaseous density 

 and of apiodal figure revolving round one another in a few hours. 

 When these contiguous stars move in orbits the plane of which passes 

 through the earth, their movement is made evident as Algol variation. 

 The orbits of stars in this stage of development are nearly all 

 circular. 



As the component stars move further and further apart, their 

 orbits take to themselves a greater eccentricity ; the influence of 

 this eccentric motion is made evident as short period variation. 



And then in the process of ages the star becomes a visual 

 binary. 



There is nothing in this statement of cosmic evolution to offend 

 either our sense of the necessity to make observation and theory 

 agree, or our appreciation of that unity and order which compasses 

 the heavens as a garment. 



Mr. E. T. A. Innes adds : — 



This star was first suspected to be variable by Professor J. C. 

 Kapteyn, of Groningen, from his examination of the plates taken for 

 the Cape Photographic Divichmusterung. Four plates, covering the 

 region of the sky where this star is situated, were sent him from the 

 Eoyal Observatory ; on three, the star appeared of the 9'6 magnitude,, 

 but on the fourth plate it was only of the 10-5 magnitude. Lest this 

 might be due to some photographic defect, Professor Kapteyn 



