114 Colours of Stars. 



says, " The bright hues were not there, and greenish-white 

 and pinkish- white were all I could affirm. May 10, hues more 

 faint j I could only record them as dull white, both A and B. 

 Aug. 1, A, greenish-white ; B, yellowish : both changing 

 nightly till Aug. 12, when they showed as in the Cycle — A, 

 apple green ; B, cherry red. A first showed signs of deep- 

 ening colour, the hues becoming more apparent every night ; 

 B changing from yellow to red more rapidly. The change," 

 he adds, " was very palpable after an interval of three or four 

 nights." 



Our readers will no doubt avail themselves of the present 

 season to examine this (< crucial instance,'" as Smyth calls it, 

 " of sidereal colour-changing." I have observed it but once 

 with my present instrument — on Aug. 6 — when I found it rosy 

 and greenish, but thought the red more decided than the 

 green. Out of six eye-pieces, of different kinds, ranging from 

 111 to 451, one only, of Steinheil's construction, failed to show 

 the difference of colour. 



It would be well if those who feel an interest in the inquiry 

 would note down- — with the date of the observation — any 

 remarkable colour in a star, single or associated, which may 

 pass through their field of view, and which can be identified 

 on future occasions. This will involve very little trouble, 

 especially when it has become familiar to us ; the perception 

 of such colours, cultivated by practice, will become at once 

 more sensitive and more accurate; and the record of our 

 observations may ultimately be found of considerable value, 

 while we shall be at any rate sufficiently compensated by the 

 beauty and variety which we shall thus discover in every 

 quarter of the heavens. 



A few remarks on the subject of the distribution of star- 

 colour will close this already extended discussion. 



The statistics of colour occurring in pairs, as determined 

 by Struve, will be found in Intellectual Observer, March, 

 1862, p. 149. They lead at once to the conclusion thafc 

 although there is a preponderance, as we have already pointed 

 out, of the more refrangible end of the spectrum among the 

 minuter components, the reverse is decidedly the case with 

 the brighter ones ; and this is so evident, not merely among 

 associated but insulated stars, that Sir John Herschel has said 

 that "no green or blue star (of any decided hue) has, we 

 believe, ever been noticed unassociated with a companion 

 brighter than itself." So general an expression may not accord 

 in its fullest sense with the results of other observers ; yet 

 there can be no doubt of the general predominance, next after 

 white, of yellow, orange, and ruddy hues. The ancients recog- 

 nized only white and red stars among those visible without a 



