S. P. Langley— Minute structure of the Solar Photosphere. 98 
To represent the gradations of light from the intensest splen- 
dor to the darkness of the nuclei, we have here only the limited 
range between a white and a black pigment. This almost 
compels partial falsity in the degrees of shade, and there is, for 
instance in the drawing, a relative exaggeration of the shade 
which marks the outer boundary of the penumbra, and without 
but wholly ade up, as it appears on a first examination, of 
Cloud-forms whose structure makes them seem like r 
Sheaves of some elongated objects. These sheaves Mr. Dawes 
tenuity, which by their aggregation make the “thatch,” just as 
the minute granules of the photosphere compose the ‘* rice- 
grains.” These filaments I have observed to have a tendency 
