YET A YEAR LATER. 95 



photograph was removed by the circumstance that two 

 other gaps, less marked but still recognisable, appeared 

 in both photographs. 



I have dwelt somewhat at length on this V-shaped 

 gap, because it is in reality of extreme importance. 

 On no former occasion had any distinctive feature of 

 the corona been unmistakably recognised at stations 

 far apart. It happened strangely that on the first 

 occasion upon which the corona was successfully photo- 

 grapli^d, a very remarkable and characteristic pecu- 

 liarity was presented by the corona. Favourable as 

 are the circumstances of the approaching eclipse, it is 

 not by any means certain that the photographs taken 

 at distant stations will be so well suited for comparison 

 as those taken during the eclipse of last year. So that 

 it is well to set store by the great fact which was 

 established by the observers of the latter eclipse. The 

 following words taken from a letter addressed to Mr. 

 Brothers by Sir John Herschel, serve to indicate the 

 importance which he attached to the photographic 

 records of the V-shaped gap : ' Assuredly,' he wrote, 

 'the decidedly marked notch or bay in both photo- 

 graphs ' (those taken at Cadiz and Syracuse) * agreeing 

 so perfectly in situation (marked so definitely by its 

 occurrence just opposite the middle point between 

 two unmistakable red prominences) is evidence not to 

 be refused, of its extra-atmospheric origin. 1 ... A 



1 The omitted words relate to the absence of any signs which could 

 show the corona to be a phenomenon produced within the space sepa- 

 rating the earth from the moon. On this point, further, I may remark 

 that I had occasion to submit to Sir John Herschel certain considera- 



