36 Dr. and Mrs. Iluggins. On Wolf and [Dec. 11, 



showed at once the substantial accuracy of Yogel's measures, and the 

 striking difference of position of the band in the star No. 4001 from 

 tint which it holds in the other two stars. 



The obvious want of agreement of the star bands with the blue 

 band of the Bunsen flame was seen at once. Their relative positions 

 appeared to agree substantially with the positions represented in No. 2 

 and No. 3 of the diagram, which are based on Vogel's measures. 

 More careful and repeated observations brought out clearly, as is 

 indeed shown by Vogel's curve, that the star bands differ in character 

 as well as in position from the blue band of the hydrocarbon flame, 

 and also in some respects from each other. 



Before giving in more detail the results of our observation on each of 

 the three stars, it should be stated that in all the stars the continuous 

 spectrum is not in our instruments a short one, ending before the 

 position of the bright blue band is reached. On the contrary, an 

 examination with all three spectroscopes showed that the continuous 

 spectrum, though enfeebled by absorption a little before reaching the 

 blue band, can be traced, as is shown in Vogel's curves, quite up to 

 the band, and indeed extends for a long distance into the violet beyond 

 the bine band. The blue band does not in our instruments stand out 

 bright beyond the end of a short continuous spectrum, but falls upon 

 a fairly luminous continuous spectrum, which can be traced past the 

 blue band into the violet, apparently as far as the eye could be expected 

 to follow it. 



We suspected blight lines or bands in the region more refrangible 

 than the blue band, but in such faint objects this is a point which 

 should be determined by photography. 



Professor E. C. Pickering has since kindly informed us that his 

 photographs of the star No. 4001, which extend into the ultra-violet 

 region, show beyond the blue band the bright hydrogen lines at 434, 

 410, 397, and 389 ; and also other bright lines at 462, 455, 420, 406, 

 402, 395, and 388. 



In his photographs of the stars 4013 and 3956, however, the only 

 well-marked line is in the blue at 470. 



Star 4001. In this star, as is shown by Vogel's measures and 

 curve, the bright blue band is less refrangible than in the other 

 two stars, and approaches therefore nearer to the position of the blue 

 band of the hydrocarbon flame. The appearance and position of the 

 band in the star as contrasted with that of carbon, when observed in 

 spectroscope B, are represented in spectrum No. 4 of the diagram. 



The brightest part of the band, from about X 468 to X 469, falls off 

 rather suddenly in brightness at about these wave-lengths, but can be 

 traced towards the red as far as about X 471 '5, and as far in the blue 

 ns about X 465*5. 



