On the Spectra of some of the Fixed Stars. 153 



lines with those of the solar and lunar spectrum, are given, and the 

 authors then proceed to give the results of their observations. 



Careful examination of the spectrum of the light obtained from 

 various points of the moon's surface failed to show any lines resem- 

 bling those due to the earth's atmosphere. The planets Venus, Mars, 

 Jupiter, and Saturn were also examined for atmospheric lines, but 

 none such could be discovered, though the characteristic aspect of the 

 solar spectrum was recognized in each case ; and several of the prin- 

 cipal lines were measured, and found to be exactly coincident with 

 the solar lines. 



Between forty and fifty of the fixed stars have been more or less 

 completely examined ; and tables of the measures of about 90 lines 

 in Aldebaran, nearly 80 in a Orionis, and 15 in j3 Pegasi are given, 

 with diagrams of the lines in the two stars first named. These dia- 

 grams include the results of the comparison of the spectra of various 

 terrestrial elements with those of the star. In the spectrum of 

 Aldebaran coincidence with nine of the elementary bodies were ob- 

 served, viz. sodium, magnesium, hydrogen, calcium, iron, bismuth, 

 tellurium, antimony, and mercury ; in seven other cases no coinci- 

 dence was found to occur. 



In the spectrum of a Orionis five cases of coincidence were found, 

 viz. sodium, magnesium, calcium, iron, and bismuth, whilst in the 

 case of ten otBer metals no coincidence with the lines of this stellar 

 spectrum was found. 



(3 Pegasi furnished a spectrum closely resembling that of a Orionis 

 in appearance, but much weaker : only a few of the lines admitted 

 of accurate measurement, for want of light ; but the coincidence of 

 sodium and magnesium was ascertained ; that of barium, iron, and 

 manganese was doubtful. Four other elements were found not to be 

 coincident. In particular, it was noticed that the lines C and F, 

 corresponding to hydrogen, which are present in nearly all the stars, 

 are wanting in a Orionis and j3 Pegasi. 



The investigation of the stars which follow is less complete, and 

 no details of measurement are given, though several points of much 

 interest have been ascertained. 



Sirius gave a spectrum containing five strong lines, and numerous 

 finer lines. The occurrence of sodium, magnesium, hydrogen, and 

 probably of iron, was shown by coincidence of certain lines in the 

 spectra of these metals with those in the star. In a Lyrce the 

 occurrence of sodium, magnesium, and hydrogen was also shown by 

 the same means. In Capella sodium was shown, and about twenty 

 of the lines in the star were measured. In Arcturus the authors 

 have measured about thirty lines, and have observed the coincidence 

 of the sodium line with a double line in the star- spectrum. In Pol- 

 lux they obtained evidence of the presence of sodium, magnesium, 

 and probably of iron. The presence of sodium was also indicated in 

 Procyon and a Cygni. 



In no single instance have the authors ever observed a star-spec- 

 trum in which lines were not discernible, if the light were sufficiently 

 intense, and the atmosphere favourable. Rigel, for instance, which some 

 authors state to be free from lines, is filled with a multitude of fine lines. 



