260 FRAGMENTS OF SCIENCE. 



light of our electric lamp shining through such a composite 

 flame would give us a spectrum cut up by dark lines, 

 exactly as the solar spectrum is cut up by the lines of 

 Fraunhofer. 



Thus by the combination of the strictest reasoning with 

 the most conclusive experiment, we reach the solution 

 of one of the grandest of scientific problems the constitu- 

 tion of the sun. The sun consists of a nucleus surrounded 

 by flaming atmosphere. The light of the nucleus would 

 give us a continuous spectrum, like that of our common 

 carbon-points; but having to pass through the photosphere, 

 as our beam had to pass through the flame, those rays of 

 the nucleus which the photosphere can itself emit are 

 absorbed, and shaded spaces, corresponding to the partic- 

 ular rays absorbed, occur in the spectrum. Abolish the 

 solar nucleus, and we should have a spectrum showing a 

 bright line in the place of every dark line of Fraunhofer. 

 These lines are therefore not absolutely dark, but dark by 

 an amount corresponding to the difference between the 

 light of the nucleus intercepted by the photosphere, and 

 the light which issues from the latter. 



The man to whom we owe this noble generalization is 

 Kirchhoff, professor of natural philosophy in the Uni- 

 versity of Heidelberg;* but, like every other great dis- 

 covery, it is compounded of various elements. Mr. Talbot 

 observed the bright lines in the spectra of colored flames. 

 Sixteen years ago Dr. Miller gave drawings and descriptions 

 of the spectra of various colored flames. Wheatstone, 

 with his accustomed ingenuity, analyzed the light of the 

 electric spark, and showed that the metals between which 

 the spark passed determined the bright bands in the 

 spectrum of the spark. Masson published a prize essay on 

 these bands; Van der Willigen, and more recently Pliicker, 

 have given us beautiful drawings of the spectra, obtained 

 from the discharge of RuhmkoriFs coil. But none of these 

 distinguished men betrayed the least knowledge of the 

 connection between the bright bands of the metals and the 

 dark lines of the solar spectrum. The man who came 

 nearest to the philosophy of the subject was Angstrom. 

 In a paper translated from Poggendorffs Annalen by 

 myself, and published in the Philosophical Magazine 



* Now professor in the University of Berlin. 



