ON THE STUDY OF DOUBLE STARS BY AMATEUR 



OBSERVERS. IV. 



Bv G. F. CHAMBERS, F.R.A.S. 



VARIABILITY OF DOUBLE .STARS. 



On the question of the variabihty ami rolours of 

 Double Stars, Innes has some remarks which are 

 worth reproduction. After stating that onl\- in a 

 few striking cases has he gi\'en any attention to 

 questions of variability, he suggests that " It is 

 highly probable that the variation of light so often 

 recorded is in some sense real." In consequence of 

 this remark I have generally included in my notes 

 the question of variabilit\- where any materials were 

 available for doing so. It must never be forgotten, 

 however, when one has to deal with or consult 

 photographic magnitudes, that these are often fainter 



than the \'isual : a fact in nearh' all instances arising 

 in the case of stars which are \'ellow or reddish, these 

 colours, it is well known, having less actinic power 

 than white light. 



As regards colours, Innes's policv was substantiallv 

 adopted b\' myself long before I knew that it was his. 

 He says : " V'ery little attention has been given to 

 colours. Where, however, they seem generallv agreed 

 on, they are quoted. The minute differences of shade 

 recorded by some obser\'ers have been omitted as use- 

 less if not misleading." I have made some remarks on 

 the colour question at an earlier point in this paper. 



THE SOUTHERN CONSTELLATIONS. 



So man\- of the Stars which have come into notice 

 latel\- thiniigh the labours of Innes being Southern 

 Heniisi)here Stars, it is necessary to pay some special 

 attention to the allotment of constellation names to 

 them in default of his having done so in the xast 

 number of cases. The question of the boundaries. 

 and, indeed, of many of the names of those 

 constellations was long a thorny one, and matters 

 were not improved by the drastic proposals for the 

 radical reform of the boundaries of many of the 

 Southern Constellations put forth by the late Dr. 

 B. A. Gould in his i'raiioniefria Argeiititia. published 

 at Buenos Ayres in 1879. It is no wonder that Dr. 

 Gould's proposals have not met with favour, for 

 under his schemes the Constellations were cut up 

 into slices and pieced together in (to put it 

 mildh') a most inconvenient fashion. liad as 

 his divisions might have been when recorded on 

 maps, matters were tenfold worse when one tried by 

 consulting his Catalogue to find the whereabouts in 

 it of an\- particular Star whose magnitude one 

 wished to learn, or to read the " Notes " printed in 

 another part of the Book. Even w hen a Star was 

 found in the Catalogue, it was always a matter of 

 some minutes more to dig up the " Note." Anyone 

 who ma\' have access to a copy of the Umnoiiwfria 

 Argentina will readily be able to judge of the time 

 and labour which would be involved in attempting to 

 collate an)- Star magnitudes, as usually stated, w ith 

 the Cordoba magnitudes. The advantage of doing 

 this has, however, been in great jwrt removed, since 



the [Hiblicatiiin of Dr. Gould's results, b\' tlie issue of 

 the Southern Udrvard I'hotonictry. the value of 

 which two volumes, in combination with the 

 Northern volume, it is impossible to o\-er estimate. 

 I make these remarks on Gould's labours with regret, 

 because his criticism on the names and boundaries 

 of certain Constellations and on the lettering of 

 conspicuous Stars' are \'ery forcible in their wav, 

 but his endeavours to build a substitute for what he 

 would pull down ha\e, like many other "reform" 

 efforts, resulted in confusion worse confounded. 



The reader will perhaps now expect some statement 

 as to how I should treat the matter, which is one by 

 no means lacking in practical importance, having 

 regard to the large and increasing number of amateur 

 astronomers who are compelled to carry on their 

 labours unprovided with e<iuatoria] mountings, and, 

 therefore, are dependent on maps tor finding the 

 objects which the\' wish to observe. 



I ma\' state generally that I should for the most 

 part accept the jirinciples laid down by the late 

 Mr. E. J. Stone in the preface to his " Catalogue of 

 12.441 Stars for the epoch of 1880." Without quoting 

 in detail his statement of those principles, I may 

 gi\'e in his own words his jirefatory summary of 

 them, .\fter [irotesting against radical changes 

 (apparenth' ha\'ing Dr. Gould in his thoughts), he 

 sa\-s : " I have, therefore, in the present Catalogue, 

 followed the system introduced by Lacaille, but with 

 the rectifications of boundaries and modifications 

 recommended b\' Sir John Herschel. This system 



Unuioiii-iif'lnd Ariiciitnia, the 4to \(iliuiic. pp. 4<S-7y, 



426 



