[ 29 ] 
nmenta! proof, that the luminous matter acquires 
fome degree of (hade, when forming the (ides of an 
excavation, yet it is uncertain, if this be merely the 
effect of petition, and much more fo, if any dif- 
ferent modification ofpofition could ever diipofe it 
to put on a brighter or more fulgid appearance. 
Yet, after all, may not thefe faeuUe, &c. depend 
upon fome irregularities in the bright furface of 
the fan ? For may not the luminous matter, by be- 
ing agitated by the fame eaufe to which the lpots 
owe their origin, though in a left degree, have its 
lurface perpetually difturbed, and made irregular,., 
and thus give occafion to a variety of light and 
(bade, fufficient perhaps to produce the phenomena 
under conlideration ? And does not tins conjecture 
receive further confirmation, when we confider, 
that thefe facula?, &c. are found only in that zo- 
diac, within which the fpots appear, and that they 
always abound molt in the neighbourhood of the 
fpots themfelves, or where fpots recently have 
been ? For in t'nofe undifturbed regions of the fun 
which lye towards his poles, and where no fpots 
ever appear, and which sciieiner calls the plagce 
tcquabiles, we never dif cover any diverfity of ap- 
pearance. 
Thus we have endeavoured to give a general 
idea of the production, changes, and decay of the 
Iclar fpots, confidered as excavations in the body 
of the iun; a thing which feems to be eftnbl iilaed • 
from the obfervations deferibed in the firft part of 
this paper. But concerning the nature of that 
mighty agency, which occafions thole amazing 
commotions in the luminous matter, or concern- 
mg. 
