360 FRAGMENTS OF SCIENCE 



the solar nucleus, and we should have a spectrum show- 

 ing a bright line in the place of every dark line of Fraun- 

 hofer. These lines are therefore not absolutely dark, but 

 dark by an amount corresponding to the difference be- 

 tween the light of the nucleus intercepted by the photo- 

 sphere, 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; 1 but, like every other great discov- 

 ery, 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 descrip- 

 tions of the spectra of various colored flames. Wheat- 

 stone, 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 es- 

 say on these bands; Van der Willigen, and more recently 

 Pliicker, have given us beautiful drawings of the spectra, 

 obtained from the discharge of RuhmkorfTs coil. But 

 none of these distinguished men betrayed the least knowl- 

 edge 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 Angostrom. In a paper translated from PoggendorfFs 

 "Annalen" by myself, and published in the "Philosoph- 

 ical Magazine" for 1855, he indicates that the rays which 

 a body absorbs are precisely those which it can emit when 

 rendered luminous. In another place, he speaks of one 

 of his spectra giving the general impression of a reversal 



1 Now Professor in the University of Berlin. 



