PHYSICAL BASIS OF SOLAR CHEMISTRY 361 



of the solar spectrum. Foucault, Stokes, and Thomson, 

 have all been very close to the discovery; and, for my 

 own part, the examination of the radiation and absorption 

 of heat by gases and vapors, some of the results of which 

 I placed before you at the commencement of this dis- 

 course, would have led me in 1859 to the law on which 

 all Kirchhoff's speculations are founded, had not an acci- 

 dent withdrawn me from the investigation. But Kirch- 

 hojff's claims are unaffected by these circumstances. True, 

 much that 1 have referred to formed the necessary basis 

 of his discovery; so did the laws of Kepler furnish to 

 Newton the basis of the theory of gravitation. But what 

 Kirchhoff has done carries us far beyond all that had 

 before been accomplished. He has introduced the order 

 of law amid a vast assemblage of empirical observations, 

 and has ennobled our previous knowledge by showing its 

 relationship to some of the most sublime of natural phe- 

 nomena. 



Science— V — 16 



