44 Dr. and Mrs. Huggins. On Wolf and [Dec. 11, 



As the main object of our examination of these stars was to deter- 

 mine whether the bright band in the blue was to be regarded a 

 showing the presence of carbon by its coincidence with the blue band 

 of the hydrocarbon flame, we were not able, from the pressing claims 

 of other work, to extend our examination to many other points in con- 

 nexion with the spectrum of these faint stars, for an exhaustive exami- 

 nation of which, indeed, our instruments are not sufficiently powerful. 



We have stated already that the fairly luminous continuous 

 spectrum reaches up to the bright band in all three stars, and extends 

 beyond into the violet, as far as the eye could be expected to follow it. 



The spectra are weakened at many points by what appear to be 

 absorption bands, and are crossed by several brilliant lines, the 

 positions of some of which have been given by Vogel and by Copeland. 



An examination with spectroscope B of some of these bright lines, 

 as they appear under small dispersion, showed them to be really not 

 single lines, but short groups of closely- adjacent bright lines. 



One of the brightest of these lines is found in the star No. 4013, at 

 the position, according to Vogel, of X 570. 



Dr. Copeland's measure for this line is X 568'9 in star 4013, and 

 X 570-4 in the star 3956. 



As this position is not very far from that of the green pair of 

 sodium lines at X 5687 and X 5681, it has been suggested that the line 

 in the star is due to sodium, though there is no line of comparable 

 brightness in the star's spectrum at the position of the dominant pair 

 of the sodium spectrum at D,* 



On confronting in spectroscope B the star line with the green 

 sodium lines, the bright space in the star's spectrum was seen to con- 

 sist of a short group of several bright lines close together, and nearly 

 equally bright. This group appeared to extend through about four 

 times the interval of the sodium pair, which would make the length 

 of the group about X 0024. The green sodium lines cross the group 

 at about one-fourth to one-third of the length of the group from its 

 more refrangible end. The group in the star is rather less bright at 

 the two ends, but there is no gradual shading off in either direction, 

 as in the case of a fluting. 



When we examined this part of the spectrum with the small disper- 

 sion of a prism of 45, we were pretty sure of a feeble bright line, less 

 refrangible than the pair of bright groups in the yellow, and not far 

 from the position of D. We were not able to see this line in spectro- 

 scope B with sufficient clearness to enable us to fix its position. It 

 may be D, or, perhaps more probably D 8 . 



* The 570 line is most probably the green sodium line 569, the absence of the 

 yellow sodium being explained by the half-and-half absorption and radiation men- 

 tioned in the discussion of the causes which mask and prevent the appearance of a 

 line in a spectrum (Bnkerian Lecture for 1888, ' Roy. Soc. Proc.,' vol. 44, p. 41). 



