iv "BUNSENIANA" 69 



had begun their memorable work on spectrum analysis, 

 but on returning there in the summer of 1860 I soon 

 came into the thick of it, and translated their epoch- 

 making memoir in Poggendorf s Annalen for the Philo- 

 sophical Magazine. I shall never forget the impression 

 made upon me by looking through KirchhofFs magnifi- 

 cent spectroscope, arranged in one of the back rooms of 

 the old building in the Hauptstrasse, which then served 

 for the Physical Institute, as I saw the coincidence of 

 the bright lines in the iron spectrum with the dark 

 Frauenhofer's lines in the solar spectrum. The evidence 

 that iron, such as we know it on this earth, is con- 

 tained in the solar atmosphere, struck one instantly 

 as conclusive. And yet not more than forty years 

 had elapsed since Comte in his Systeme, arguing that 

 investigators should not waste their time in attempting 

 the impossible, used as an example of what he meant 

 by the impossible that the knowledge of the composi- 

 tion of the sun at a distance of 91 millions of miles 

 must for ever remain unattainable. Now we know 

 the chemical composition of the solar atmosphere 

 almost as well as we know that of our own. But who 

 can say how much more we have yet to learn of both ? 

 It was only a day or so ago that no fewer than four 

 elements, hitherto unknown and wholly unexpected, 

 were discovered in the air we breathe. 



One of the most successful lectures I ever gave 

 at the Royal Institution was that which I delivered 

 on March ist, 1861, on " Bunsen and Kirchhoffs 

 Spectrum Observations." It is interesting now to 

 remember that at that time no one in England had 

 been able to project the bright lines of the metals on 

 the screen. I had indeed heard that an optician in 

 Paris, Duboscq by name, had done so with a certain 

 amount of success. I wished, however, to try, and 



