Photography of the Skies 



been hidden for ages to come but for photography, 

 because until that discovery was made there 

 was no apparent reason for every-day examina- 

 tion of the spectrum of a star. Indeed, until 

 then, when the lines were once carefully measured 

 they were put aside by the observer as finished 

 and definite records of the star's spectrum. 

 These first results indicate that the components 

 of Beta Aurigae are separated by an angular 

 interval of only one nine-hundred-thousandth 

 part of a degree, a quantity so small that twenty 

 years ago no one would ever dream of being able 

 to measure it. "* 



New demands give the eye new refinements: 

 the duplicity of the spectral lines of Beta Aurigag 

 was discovered by Miss A. C. Maury. Mrs. 

 W. P. Fleming of Harvard Observatory has be- 

 come so expert in detecting variable stars by 

 their spectra that she recognizes them instantly 

 among hundreds of other spectra on the same 

 plate. And mark the value of these photographic 

 spectra for subsequent investigation. Mrs. 

 Fleming says: "While an astronomer with a 

 telescope, be it ever so powerful, is at the mercy 

 of the weather, the discussion of photographs 

 goes on uninterruptedly, and is much more 

 trustworthy than visual work, since, when a 

 question of error arises, any one interested in the 



* Address by Professor H. C. Russell, government astrono- 

 mer, Sydney, to Section A, astronomy, mathematics, and 

 physics, Australian Association for the Advancement of 

 Science, 1893. 



