238 The Eclipse of Last December. [April, 



berances clearly, and choosing the most brilliant part of the 

 corona, he directed the spectroscope towards it ; and whilst 

 the assistant kept it fixed, he was able to distinguish plainly 

 the spectrum of the protuberances from that of the corona. 

 This last was continuous, and had two very brilliant bands, 

 one in the green near Fralinhofer's e, and another in the 



yellow-green The shortness of the time, and the 



difficulty of calculating the scale would not allow us to fix 

 the lines in question with more precision." 



As regards the agreement of the line which has hitherto 

 been spoken of as Kirchhoff's 1474, with that well-known 

 iron line, Professor Young remarks, " the difference, if any 

 (and I have not found the slightest reason to suspect the 

 least want of coincidence in observations with the whole 

 dispersive power of thirteen prisms) is less than i-ioth of 

 one division of Kirchhoff's scale. There is no solar dark line 

 but 1474, therefore, with which this bright line can be sup- 

 posed to agree. 



There seems to be no valid reason for regarding this line 

 as belonging to a new element, as has been suggested. In 

 fact, without denying the possibility that elements unknown 

 on earth may exist in the interplanetary spaces, or elsewhere, 

 it could only be on the score of very striking evidence that 

 terrestrial physicists would admit the actual existence of such 

 elements in any special instance. In this case, we have a 

 line which appears to be absolutely identical with a known 

 iron line, and is also recognisable in the spectrum of the 

 terrestrial aurora. We may reasonably inquire, therefore, 

 under what conditions the metal iron can supply this line 

 without exhibiting the other lines belonging to the iron 

 spectrum ; but we certainly seem to have no evidence 

 favouring the supposition that a new element is in question. 

 On the contrary, the evidence, as far as it goes, is opposed 

 to such a supposition.* 



But we must now turn to the evidence afforded by direct 

 observation, supplemented as such observation has in this 

 case been by the evidence of photographic records. 



I lay no stress on the recognition of a very striking dif- 

 ference between the luminosity of the inner part of the 

 corona and that of the outlying and seemingly radiated 

 portion. For this difference is a phenomenon which has 



* We now have Zollner's study of the auroral spe&rum to show that in all 

 probability the extreme tenuity of the medium, through which the ele&rical 

 discharges causing the auroral light take place, is to be regarded as the secret 

 of the nature of the auroral spedtrum. The presence of one line of iron both 

 n the auroral and coronal spe&ra, while all the remaining lines are absent, 

 n ty thus come one day to be satisfactorily interpreted. 



