148 Mr. W. Huggins and Dr. W. A. Miller on the [May 17, 



separates F from G, a second and less brilliant line was seen. Both 

 these lines were narrow and sharply defined. Beyond these lines, and 

 at a distance a little more than one-third of that which separates the 

 second bright line from the strongest bright one, a third bright line 

 was observed. The appearance of this line suggested that it was either 

 double or undefined at the edges. In the more refrangible part of 

 the spectrum, probably not far from G of the solar spectrum, glimpses were 

 obtained of a fourth and faint bright line. At the extreme end of the 

 visible part of the less refrangible end of the spectrum, about C, appeared 

 a line brighter than the normal relative brilRancy of this part of the 

 spectrum. The brightness of this line, however, was not nearly so marked 

 in proportion to that of the part of the spectrum where it occurs, as 

 was that of the lines in the green and blue *. 



General Conclusions. — It is difficult to imagine the present physical 

 constitution of this remarkable object. There must be a photosphere of 

 matter in the solid or liquid state emitting light of all refrangibiUties. Sur- 

 rounding this must exist also an atmosphere of cooler vapours, which give 

 rise by absorption to the groups of dark lines. 



Besides this constitution, which it possesses in common with the sun and 

 the stars, there must exist the source of the gaseous spectrum. That this 

 is not produced by the faint nebulosity seen about the star is evident by 

 the brightness of the lines, and the circumstance that they do not extend 

 in the instrument beyond the boundaries of the continuous spectrum. The 

 gaseous mass from which this light emanates must be at a much higher 

 temperature than the photosphere of the star ; otherwise it would appear 

 impossible to explain the great brilliancy of the lines compared with the 

 corresponding parts of the continuous spectrum of the photosphere. The 

 position of two of the bright lines suggests that this gas may consist 

 chiefly of hydrogen. 



If, hovjever, hydrogen be really the source of some of the bright lines, 

 the conditions under which the gas emits the light must be different from 

 those to which it has been submitted in terrestrial observations ; for it is 

 well known that the line of hydrogen in the green is always fainter and 

 more expanded than the brilliant red line which characterizes the spectrum 

 of this gas. On the other hand, the strong absorption indicated by the 



end of the spectrum, when the amount of dispersion necessary for these observations was 

 employed, the exact coincidence of the line in this part of the spectrum with the red line 

 of hydrogen, though extremely probable, was not determined with equal certainty. 



* The spectra of the star were observed again on the 17th, the 19th, the 21st, and the 

 23rd. On these evenings no important alteration had taken place. On the 17th and suc- 

 ceeding evenings, though the spectrum of the waning star was fainter than on the 16th, 

 the red bright line appeared a little brighter relatively to the green and blue bright lines. 

 On the 19th and 21st the absorption lines about b were stronger than on the 16th. From 

 the 16th the continuous spectrum diminished in brightness more rapidly than the 

 gaseous spectrum, so that on the 23rd, though the spectrum as a whole was faint, the 

 bright lines were brilliant when compared with the continuous spectrum. 



