S. P. Langley—Minute structure of the Solar Photosphere. 97 
and one difficult of explanation at first, is that which I can 
best compare to the trunk of a fallen tree covered with snow, 
entirely smooth and straight upon one side, and hung with 
icicles on the other (I, to I,). 
In the spot whence this was taken, the appearance was so 
strikingly suggestive of crystalline structure, that it was 
necessary to recall that each “crystal” was from one to two 
thousand miles in length, to dispel the illusion. It is probably 
due to a rift in the photosphere (however caused), the filaments 
on aproene edges being partly drawn out and partly dissi- 
pated. 
than heat. 
The umbra of a spot, as seen with this eye-piece, is a com- 
aoe structure. The tips of the filaments, though usually 
right as if turned up by an ascending current around the 
ges, are sometimes darker toward their extremities, as in an 
. 
sketch. The awkward termination of the bridge, bearing a 
penumbra. These ordinarily here show traces of cyclonic ac- 
tion. Incipient penumbre they are, in fact, and the better our 
