S. P. Langley— Minute structure of the Solar Photosphere. 89 
laws which govern the solar rotation and the motions of the 
spots in longitude and latitude, and all are familiar with the 
results obtained by Mr. Rutherfurd; but however excellent 
these are, they show that photography in the most skillful hands 
is at present incompetent to seize multitudes of details which 
the eye recognizes. Drawings, then, are necessary, but rather 
such as imitate the fidelity of the topographical draughtsman, 
than such as aim chiefly at striking pictorial effect; and in the 
absence of the skill of an artist, I am used to try to secure accu- 
racy by reducing everything as far as is possible to micrometrie 
measurement. 
and whose faint intricate outlines tease the eye, which can 
neither definitely follow them, nor analyze the source of its im- 
pression of their existence. : 
lese appearances haye been mentioned, lest they should be 
confounded in any way with the far minuter structure now to 
scribed 
orms seen before, and which we now perceive to be due to their 
aggregation. The “dots” seen before are considerable openings 
caused by the absence of the white nodules at certain points, an 
the consequent exposure of the gray medium which forms the 
general background. These openings have been called pores; 
