THE AURORA. II 



stances which would lead us to anticipate that the light 

 is electric. 



We notice also in passing that we owe to the German 

 physicist Angstrom a large share of the researches on 

 which the above results respecting the spectrum of the 

 electric spark are founded. The reader will presently 

 see why we have brought Angstrom's name prominently 

 forward in connection with the interesting branch of 

 spectroscopic analysis just referred to. If the discovery 

 we are approaching had been effected by a tyro in the 

 use of the spectroscope, doubts might very reasonably 

 have been entertained respecting the exactness of the 

 observations on which the discovery rests. 



It was suggested many years ago, long indeed before 

 the true powers of spectroscopic analysis had been 

 revealed, that perhaps if the light of the aurora were 

 analysed by the prism, evidence could be obtained of 

 its electric nature. The eminent meteorologist Dove 

 remarked, for instance, that ( the peculiarities presented 

 by the electric light are so marked that it appears easy 

 to decide definitely by prismatic analysis, whether the 

 light of the aurora is or is not electric.' Singularly 

 enough, however, the first proof that the auroral light 

 is of an electric nature was derived from a very different 

 mode of inquiry. Dr. Robinson, of Armagh, discovered 

 in 1858 (a year before Kirchhoff's recognition of the 

 powers of spectroscopic analysis) that the light of the 

 aurora possesses in a peculiar degree a property termed 

 fluorescence, which is a recognised and characteristic 

 property of the light produced by electrical discharges. 



