THE ECLIPSE OF 1870. 65 



of the moon's seemingly black disc, light of the same 

 quality as that from the corona was received and 

 analysed by the spectroscopist. Yet, on reflection, it 

 will appear that this result was to have been antici- 

 pated ; for since during the whole eclipse the corona 

 continues visible, it follows that the air around and 

 above the observer is during the whole eclipse illumi- 

 nated by the corona. This illuminated air, therefore 

 (if its light became sensible at all), would necessarily 

 supply the same spectrum as the corona, only consider- 

 ably reduced in brightness ; and this, as we have seen 

 above, is what actually happened. 



But then it may be argued, if this be the case as 

 respects this seemingly dark part of the sky, may not 

 a portion of the light which seems to be received from 

 the corona itself which comes at any rate from the 

 direction towards which the corona lies be similarly 

 due to atmospheric reflection ? It is certain that such 

 must, indeed, be the case ; but it is also certain, from 

 the greater brilliancy of the bright lines seen when this 

 part of the sky is examined, that a portion of the light 

 which produces these lines comes from the corona itself. 

 We must, indeed, subtract a certain portion, about as 

 much, perhaps, as is received from the direction in 

 which the moon's dark body lies, the balance which 

 remains belongs to the corona itself. . 



We should, indeed, at this point reinforce the 

 spectroscopic observations . by those results which the 

 telescope used in the ordinary manner supplied. We 

 must inquire what was the apparent form, where were 



III. F 



