[ 16 ] 
PART II. 
I T appears then that the Tolar fpots are immenfe 
excavations in the body of the fun ; and that 
what hitherto hath been called the nucleus is the 
bottom, and what hath been called the umbra the 
Hoping (ides of the excavation. It alfo appears, 
that the Tolar matter, at the depth of the nucleus, 
does not emit light, or emits To little, as to appear 
dark compared to that refplendent fubdance at the 
Turface ; that this beauteous fubdance is at the 
furface, mod fulgid ; and when any of it is, Teen 
below the general level, forming the Tides of an 
excavation, that then its ludre is Tomehow im- 
paired, To as to give the appearance of a furround- 
ing umbra. Here our induction ends. To pro- 
ceed further would be to carry it beyond its true 
limits, and to intermix with conclufions, which are 
certain and manifed, the fuggedion of hypothefes, 
which at bed are precarious and liable to error. 
But from what we have now Teen, many curious 
Speculations do naturally prefent themfelves. By 
what myderious procefs is it, that thofe adonifh- 
ing excavations are at fird produced? What is the 
nature of that lhining fubdance, which is thereby 
perpetually didurbed? To what are we to afcribe 
: the darknefs of the nucleus, and the diminilhed 
ludre of the umbra ? And what conceptions are we 
-to form of the many drange changes, and at length 
of the final decay of all thefe appearances, whereby 
*thofe regions of the Tun, that were To hurt and dif- 
•figured, again undergo a renovation? 
We 
