14 W. A. Norton on the Corona in Eclipses of the Sun. 



"bustion or of electric discliarges. As it is hardly supposable 

 that an actual combustion could prevail at the distance of tens, 

 and hundreds of thousands of miles from the sun's photosphere, 

 in regions where, if any solar atmosphere exist, the results of 

 recent observations with the spectroscope by Lockyer and 

 Frankland lead us to believe that it can only be the faintest 

 possible trace of it, we must infer that the light of the corona is 

 of electric origin. 



In the hands of Prof Young and Prof. Winlock the spectro- 

 scope has obtained direct evidence of a physical correspondence 

 between the solar corona and terrestial auroras. Prof Young 

 observed in the spectrum of the corona a bright line the posi- 

 tion of which he gives as 1474 on Kirchoff 's scale, and which 

 proves to be in coincidence with a small line marked as iron on 

 Kirchofi's and Angstrom's maps. He remarks that " it turns 

 out also to coincide very closely if it is not (which is much more 

 probable) absolutely identical with a line recently discovered by 

 Prof Winlock of Cambridge, in the spectrum of the aurora 

 borealis. He also saw two other fainter lines in the spectrum of 

 the corona which coincided quite closely with other lines re- 

 ported by Prof Winlock as visible in the spectrum of the 

 aurora. In view of these results of spectroscopic observation 

 he remarks, as follows : "At present it seems pretty likely that 

 the spectra of the corona and the aurora borealis are identical, 

 with only such differences in the intensity of their lines as we 

 might naturally expect, and that very probably the identity 

 extends to the essential nature of the phenomena themselves." 



The detection of the same iron line in the aurora and corona, 

 taken in connection with the well established fact that the va- 

 por of iron is present in the photosphere and chromosphere of 

 the sun, and that the magnetic features of the aurora lead to 

 the natural conclusion that some form of ferruginous matter 

 the substance of auroras, for which no terrestrial 

 reasonably be assigned, conducts to the inference 

 that the terrestrial auroral matter is derived from the sun, and 

 adds to the weight of accumulative evidence in support of the 

 theory I have advocated that the corona is made up of material 

 emanations from the sun. 



Note.— Some personn have conjectured that the corona might be produced by 

 the passage of the sun's r.iys through the earth's atmosphere, but it may readUy 

 be shown that this ig impossible. When one reflects that the half width of the 

 moon's shadow, in the larger eclipse?, is as great as the estimated height of the 

 atmosphere, it will be seen that, to an observer on the central line of the eclipse 

 the line of sight will not fall upon the illuminated portion of the atmosphere ex- 

 e angle to the line of direction of the 



