1890.] Rayefs Bright-Line Stars in Cygnus. 45 



In No. 4001, Vogel saw a line at the position of the F line of 

 hydrogen. It is probable that this line, as is the case in so' many 

 stars in which it appears bright, is variable, as we were not able 

 to see it when the H/3 line from a vacuum-tube was thrown in. In 

 the similar star D.M. + 37 3821, as we have stated already, the F 

 line of hydrogen was very bright. 



We were unable to detect in any of the stars a brightening of the 

 spectrum at the position of the chief line of the bright-line nebnlae. 

 For this examination the lead line at A, 5004 - 5 was thrown in, and 

 the continuous spectrum of the star near to this position carefully 

 scrutinised. 



In their original paper, Wolf and Rayet state that they were not 

 able to detect any nebulosity about the stars. They say : " Elles ne 

 presentent non plus aucune trace de nebulosite " (loc. cit., p. 292). 



In a recent paper, Mr. Keeler, of the Lick Observatory, confirms 

 this view. He says : " At my request, Mr. Burnham and Mr. Barnard 

 examined the Wolf-Rayet stars in Cygniis for traces of surrounding; 

 nebulosity, but with only negative result."* 



Notwithstanding these negative results, it appeared to us of great 

 interest to ascertain further if any nebulosity would come out in a 

 photograph of the stars taken with a long exposure. 



Mr. Roberts responded at once to our wish when we asked his in- 

 valuable assistance, and on November 1st, of this year, he took a 

 photograph of this region of Cygnus, with an exposure of two hours. 



The three stars come out strongly upon the plate, but there is no 

 nebulosity to be seen near any of them. There are faint stars in close 

 proximity to the three stars, and apparently surrounding them, and, 

 in the case of No. 3956, six of these faint stars are seen close to it, 

 in an apparent spiral arrangement. 



Though this surrounding of faint stars should be pointed out, 

 it should, at the same time, be stated that the whole neighbouring 

 region is so densely studded with similar faint stars that it would be 

 rash, perhaps, at present to suggest that this apparent connexion of 

 the bright-line stars with faint ones near them may be other than 

 accidental. | 



* ' Publications of the Astronom. Soc. of the Pacific,' No. 11. 



f [Mr. Roberts has furnished us with the following description of the stars as 

 they appear on his photograph : 



" No. 4001 appears as a multiple star made up of one bright, two fainter, and 

 one very faint star partly behind the others ; there is also a fourth bright star close 

 to the multiple star. The group is surrounded by at least eight faint stars within 

 a radial distance of 86" of arc from centre to centre. 



" No. 4013. The photo-image of this star is made up of three stellar images 

 touching each other in a line slightly curved. Two are bright and one faint ; and 

 there are indications of two other faint stars behind the two bright ones. This 



