[ 22 ] 
But to proceed. As we know, from experience, 
that the {pots are of a tranflent nature, not lafting 
upon the fun for a long fpace of time, does it not 
feem reafonable to think, that their gradual de- 
creafe, as mentioned in article 4th, is occalionedby 
the luminous matter encroaching again upon that 
part of the dark globe, which had been uncovered ? 
And from this may we not infer, that the lumi- 
nous matter gravitates, and is in fome degree fluid; 
for thereby would it not have a tendency to flow 
down, in all directions, and encroach, fo as at laft 
to cover the nucleus? And do not thefe things 
appear further probable, when we reflect upon that 
uniform inclination, which the fides of the umbra, 
or excavation, have to the external furface of the 
fun’s body? For does not this indicate a fluid fort 
of matter gradually yielding to the force of gra- 
vity ? And again, is not this notion further fup- 
ported, when we confider the property mentioned 
in the 5th article, namely, that the exterior boun- 
dary of the umbra never conflfts of (harp angles or 
turnings, but is always curvilinear, and, moft fre- 
-quently, of a round form: for we know, that this 
boundary is nothing elfe but the lip of the exca- 
vation, which, on fuppofition that the luminous 
matter pofleffes fome degree of fluidity, will not 
be difpofed, either in enlarging or contrafling, to 
..become irregular by fudden or {harp turnings? 
Upon fuppofition that the furface of the dark 
globe of the fun is fmooth and level, it may be 
surged, that the nucleus of a fpot, whilft upon the 
decreafe, lhould, according to the prefent view of 
things, always acquire a figure, at leaft nearly, cir- 
cuit. 
