1864.] 



some of the Fixed Stars, 



243 



details of the methods adopted for testing the exact coincidence of the 

 corresponding metallic lines with those of the solar and lunar spectrum, 

 are given, and the authors then proceed to give the results of their obser- 

 vations. 



Careful examination of the spectrum of the light obtained from various 

 points of the moon's surface failed to show any lines resembling 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 disco- 

 vered, though the characteristic aspect of the solar spectrum was recognized 

 in each case ; and several of the principal 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 com- 

 pletely examined ; and tables of the measures of about 90 lines in Alde- 

 baran, nearly 80 in a Orionis, and 15 in /3 Pegasi are given, with dia- 

 grams of the lines in the two stars first named. These diagrams include 

 the results of the comparison of the spectra of various terrestrial ele- 

 ments with those of the star. In the spectrum of Aldebaran coincidence 

 with nine of the elementary bodies were observed, viz. sodium, magnesium, 

 hydrogen, calcium, iron, bismuth, tellurium, antimony, and mercury ; in 

 seven other cases no coincidence 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 

 other 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 accu- 

 rate 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 par- 

 ticular, 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 

 13 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, mag- 

 nesium, and hydrogen was also shown by the same means. In Capella 

 sodium was shown, and about twenty of the lines in the star were mea- 

 sured. 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 Pollux they obtained evidence of the presence of sodium, 



VOL. XIII. U 



