PHOTOGRAPHS OF THE CORONA. 



119 



Comparing the photographs taken at Creston, Wyoming, with 

 Prof. Newcomb's drawing (see p. 1 64) to which allusion has already' 

 been made, when, by the use of a black disk to screen his eyes 

 from the glare of the inner corona, he was able to trace its 

 extent in two great equatorial wings to a distance of twelve 

 diameters from the centre of the sun, it would seem possible 

 that the two great wings which he has described were not 

 wings indeed, but two pairs of straight rays forming the 

 completion of the synclinal groups east and west of the sun. 1 

 However this may be, the resemblance is certainly great between 



CONTOUR LINES FROM THE PHOTOGRAPHS, 1878, JULY 29. 



the double ray in the N.W. in 1878, and the triple straight ray 

 in the same neighbourhood in 1898. In any case we may take 

 it that the essential difference between a maximum and a 

 minimum corona is that at maximum the synclinal groups 

 are numerous and distributed indifferently round the sun, 

 whilst at minimum they are few and are restricted to the 

 neighbourhood of the equator. 



The synclinal groups are far from being the only type of 

 coronal form. The 1898 eclipse brought into very beautiful 

 relief those plume-like forms which, because they are seen most 

 easily and distinctly in the neighbourhood of the pole, are 



