the Nature of the Sun. 267 
take away as much light and heat as required, has given me 
additional facility of making a great number of particular ob- 
servations ; and, as they have been all directed to an investiga- 
tion of certain points, I shall give them here, in the order which 
the arrangement of my subject will require. 
It will be necessary, before I can enter into a detail of the 
observations, to give notice that, from an improved knowledge 
of the physical construction of the sun, I have found it conve- 
nient to lay aside the old names of spots, nuclei , penumbra , 
faculce, and luculi, which can only be looked upon as figurative 
expressions that may lead to error. Nor were these few terms 
sufficient to describe the more minute appearances on the sun, 
which I have to point out. 
The expressions I have used are openings , shallows, ridges; 
nodules , corrugations, indentations , and pores. It will not be 
amiss to give a short explanation of these terms. 
Openings are those places where, by the accidental removal 
of the luminous clouds of the sun, its own solid body may be 
seen ; and this not being lucid, the openings through which 
we see it may, by a common telescope, be mistaken for mere 
black spots, or their nuclei. 
Shallows are extensive and level depressions of the luminous 
solar clouds, generally surrounding the openings to a consider- 
able distance. As they are less luminous than the rest of the 
sun, they seem to have some distant, though very imperfect, 
resemblance to penumbras ; which might occasion their having 
been called so formerly. 
Ridges are bright elevations of luminous matter, extended in 
rows of an irregular arrangement. 
Nodules are also bright elevations of luminous matter, but 
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