20 Report 8. A. A. Advancement of Science. 



Half a century ago this relation between the form, movements and 

 evolution of a s^'stem and its light changes was unknown, or, if known, 

 had not become a working hypothesis in astronomy. Consequently 

 fifty years ago the study of variable stars was a line of research leading 

 nowhere. It is not to be wondered at, therefore, that the study was 

 intermittently pursued and the search for variable stars indifferently 

 and unsystematically carried out. I have in my possession a treatise 

 on Asti'onomy dated 1718. In this book \ariable stars are dis230sed of 

 in six lines. The writer says there is evidence that one or two stars in 

 the sky vaiy iia brightness. This is all he has to say on the matter. 

 Another history a hundred years later in time devotes a single page to 

 the subject. 



Herschel's Ontlines of Astronomy, published in 1851, gives four 

 pages to variable stars ; while Grant in his History of Astronomy, pub- 

 lished a year later, gives the same proportion of his classical treatise to 

 stellar variation as Herschel did, viz., one-hundredth part. 



So much for the past. What a different position the subject 

 occupies in the astronomical literature of the present day. In one of 

 the most recent treatises on Stellar Astronomy, ^■iz., Newcomb's Stars, 

 a fourth of the whole book is devoted to stellar variation and its allied 

 problems. 



AVhat I have thus instanced regarding the ever-increasing interest 

 and importance A\hich is attached to variable star research has been 

 adduced to claim and secure more interest in a science which bids fair 

 to Ijecome the main avenue of advance into the very heart of cosmical 

 science. It must also stand as my prologue and apologue. 



In dealing with the subject of variable star research 1 purpose 

 considering : — 



(1) History of the Research. 



(2) Methods of Research. 

 (8) Results of Research. 

 (4) Problems of Research. 



The History of the Research. 



From time to time in the history of the human race there has 

 been witnessed the rare phenomenon of a star suddenly blazing forth 

 into unwonted lustre, then slowly dying away, and finally disappearing 

 from the speculation of men. 



It is natural that these signal-lights of hea\en, prophets probably 

 of a coming doom upon star, and sun, and planet, should compel the 

 attention of such thoughtful men as were privileged to witness their 

 surpassing glory. 



It is also natural that it is such major changes in brightness, 

 rather than the minor and minuter changes which periodically affect 

 so large a immber of stars, that would be observed and recorded by 

 ancient astronomers. It is improbable that they were unaware of the 

 fact that the light of many stars vary, waxing and waning like the 

 brightness of the inconstant moon. Still no record has come down to 



