30 THE PROGRESS AND SPIRIT OF 



graphy furnishes examples of the relations we are indicating. 

 Experiments show qualitative as well as quantitative differ- 

 ences in the chemical effects of light here produced ; some 

 of which we may attribute to the terrestrial media through 

 which the rays pass ; while others can hardly be explained 

 but by supposing differences in the solar light at its very 

 source, depending on the substance, configuration, or other 

 conditions of the sun itself. The singular changes, periodical 

 or otherwise, ever observable on the surface of this great 

 globe, warrant the belief in such fluctuations of its light, 

 though they may not yet tell us anything beyond this. 



But we have yet to speak of other discoveries more recent 

 in date, and illustrating, even more strikingly, these wonder- 

 ful relations of distant worlds. We allude to those researches 

 of Bunsen and Kirchhoff, which have just established a new 

 method -of analysis for metallic bodies incomparably more 

 simple, delicate, and perfect than any before known to us 

 through the coloured bands, severally produced in the spec- 

 trum by flames, in which infinitesimally small quantities of 

 these metals are present. We have not space here to dilate 

 on these remarkable discoveries, anticipated in some part by 

 the researches of Pliicker, Wheatstone, and other labourers 

 in this field ; but now well defined and opening a spacious 

 path to further enquiry. They have already brought to our 

 knowledge two metals before utterly unknown; and have 

 shown others to exist where their presence had been wholly 

 unsuspected. But the main achievement here is one which 

 forms another link between the earth and its great luminary. 

 By methods of research, equally ingenious and beautiful 

 (founded primarily on the exact coincidence of the coloured 

 bands from the metals with certain of the dark lines of the 

 spectrum, but confirmed by evidence of still higher kind), 

 these philosophers have proved the existence, in the photo- 

 sphere of the Sun, of six metals at least, familiar to us on 



