1890.] Rayefs Bright- Line Stars in Cygnus. 41 



surprised to find the blue band, which is very brilliant, not in the 

 position of the band in the stars No. 4013 and No. 3956, but less 

 refrangible, corresponding to the position of the band in the star 

 No. 4001. 



The bright band begins about X 467 and runs on to nearly X 470 - 5. 

 It is clearly not made up of flutings similar to those of the Bunsen 

 flame, but is a group of lines nearly uniformly bright throughout 

 the length of the band. The band did not appear to extend in our 

 instruments towards the red quite so far as the band of No. 4001 ; 

 it stops near the place assigned by Vogel to the beginning of the 

 band of No. 4001. 



The band is represented in spectrum No. 7 in the diagram. Direct 

 comparison with hydrogen showed that the line at F is brilliant in 

 this star. 



After some scrutiny of this part of the star's spectrum, we became 

 conscious of a very feeble brightening of the spectrum beyond the 

 bright band towards the violet, and as far as we could estimate its 

 position, at about from X 464 to X 467, that is to say, about the posi- 

 tion assigned to the band by Dr. Copeland in 1884. 



We then re-examined the spectrum of No. 4001, and were able to 

 feel pretty sure that a similar faint brightening of the spectrum 

 occurs in this star also at the same place, namely, about the more 

 refrangible position of the blue band in the stars No. 4013 and 

 No. 3956. 



Dr. Copeland, during his travels in the Andes in 1883, observed 

 7 Argus, and five small stars with bright lines in their spectra. He 

 says : " As far as my measures and estimates go, all of them belong 

 to the same class as the three Wolf -Rayet stars in the Swan, to which 

 Professor Pickering has since added a fourth outlying member."* 



Dr. Copeland gives the position of the bright blue band in <y Argus 

 as X 464-6. 



Among the stars in the great cluster G.C. 4245, near " Scorpii, 

 Dr. Copeland found a star, P. XVI 204 = Stone 9168, which has a 

 similar spectrum, namely, with a bright band in the blue and two in 

 the yellow. He found the position of the blue band to be X 465'1 . 



In the case of two other small stars with similar spectra, he found 

 respectively for the blue band the approximate measures X 463'3 and 

 X 463-6. 



These four stars were similar, therefore, at the time of the observa- 

 tions to No. 4013 and No. 3956, in which the maximum of the blue 

 band is not far from X 464, and therefore outside and beyond the 

 ordinary visible limit of the blue carbon band. 



* " An Account of some recent Astronomical Experiments at High Elevations in 

 the Andes ; " ' Copernicus,' vol. 3, 1883. 



