SECT. IT. SPECTRA OF FIXED STARS. 155 



may be concluded that their structure is to a certain 

 extent the same with that of the sun. 



Numerous observations have been made on the spectra 

 of the fixed stars, both in Britain and on the Continent. 

 In England, Mr. Huggins and Professor W. A. Miller 

 have published tables of the measures of about ninety 

 dark lines in the spectrum of Aldebaran, nearly eighty 

 in that of a Orionis or Betelgeux, and fifteen in that 

 of /? Pegasi, with diagrams of the two first which 

 include the results of a comparison of the spectra of 

 various terrestrial elements with those of the stars. 

 Thus coloured lines of sodium, magnesium, calcium, 

 hydrogen, iron, bismuth, tellurium, antimony and mer- 

 cury were found to be coincident with some of the dark 

 lines in the spectrum of Aldebaran, and besides these 

 there are numerous lines in the spectrum of this starj 

 which are probably due to forms of matter unknown teg 

 us. Coloured lines of sodium, magnesium, calcium, 

 iron and bismuth, coincided with dark lines in the 

 spectrum of a Orionis ; and /3 Pegasi had a spectrum 

 closely resembling that of a Orionis, but much fainter. 



Between forty and fifty stars were examined, and it 

 was observed that the solar lines C and F corresponding 

 to hydrogen, which are present in the spectra of nearly 

 all the stars., are wanting in those of a Orionis and /5 

 Pegasi. With a few exceptions, the terrestrial elements 

 hydrogen, sodium, magnesium, and iron, which appear 

 to be most widely diffused through the stars, are pre- 

 cisely those which with the exception of magnesium are 

 essential to life as it exists upon the earth. Besides, the 

 elements hydrogen, sodium, and magnesium, represent 

 the ocean, which is an essential part of a world similar 

 to the earth. Should any planets revolve round a Orionia 

 and Pegasi, they probably would have no hydrogen, 

 consequently, no ocean and no water : therefore, they 

 could not be inhabited by beings constituted as we are. 



