310 Dr. Herschel's Observations to investigate 
Feb. 4, 1801. Between flying clouds, I counted 31 openings 
in the sun. 
March 2, 1801. There are six different sets of openings in 
the sun. One of them consists of ten ; another of two ; the rest 
are single. 
Coarse a?id luminous Corrugations. 
Jan. 4, 1801. The corrugations are very coarse; and the 
luminous clouds seem to be very rich. 
Jan. 3, 1801. The elevations of the corrugations are all very 
luminous, like so many nodules. 
Feb. 18, 1801. The corrugations are every where very 
luminous. 
March 2. The general surface of the sun is so rich, that the 
indentations are a good deal covered by self-luminous clouds. 
From these two last sets of observations, one of which esta- 
blishes the scarcity of the luminous clouds, while the other 
shews their great abundance, I think we may reasonably con- 
clude, that there must be a manifest difference in the emission of 
light and heat from the sun. It appears to me, if I may be per- 
mitted the metaphor, that our sun has for some time past been 
labouring under an indisposition, from which it is now in a fair 
way of recovering. An application of the foregoing method, how- 
ever, even if we were perfectly assured of its being well founded, 
will still remain attended with considerable difficulties. 
We see how, in that simple instrument the barometer, our 
expectations of rain or fair weather, are only to be had by a 
consideration of many circumstances, besides its actual elevation 
at the moment of inspection. 
The tides also present us with the most complicated varieties 
