92 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



and followed the Sun's border to the instant of disappear- 

 ance. The bright, long, narrow crescent was sharply and 

 regularly defined throughout; the extremities were clear- 

 cut and pointed. As the width and length of the crescent 

 decreased, this sharpness of outline and regularity of form 

 were maintained until it became a fine line of living white; 

 and, shortening rapidly, it disappeared as a very short, fine, 

 distinct line, and not as a star at its disappearance. There 

 was no breaking of this line into points or heads; no wave 

 motion along it; no disturbance whatever of continuity or 

 regularity of form." 



"A feature of the phenomenon of totality was the vivid 

 impression that the dark body of the Moon stood out clearly 

 and unmistakably in relief in the space between the 

 observer and the coronal brightness around the obscured 

 body of the Sun, and did not lie flat and upon it, as in a 

 picture." This perspective effect resulted from the seren- 

 ity of the atmosphere, the sharpness of the Moon's outline, 

 and an impression that the dark Moon was very close to us. 



Graphic Exhibitions of Unsteadiness. 



If it were necessary to add graphic demonstration to the 

 effect of the disturbed atmosphere already described, we 

 have it in the photographs referred to in the following note 

 by Warren de la Rue, 1 where he describes the method of 

 photographing the Sun's disc, in a very small fraction of 

 a second. He says, "So rapid is the delineation of the 

 Sun's image that fragments of the limb, optically detached 

 by the ' boil ' of our atmosphere, are frequently depicted 

 on the collodion, completely separated from the remainder 

 of the Sun's disc; more frequently still from the same 

 cause the contour of the Sun presents an undulating line." 

 To this case can be added a photograph of the Sun taken at 

 the Lick Observatory January 14, 1897 ; wherein the facti- 

 tious limb is like a flocculent border of cotton or wool with 

 ragged holes through the relatively faint, irregular outline 



1 Proc. Brit. Assn. Adv't. Sci., Aberdeen, 1859, page 151. 



