& Dr. Herschel’s Obfervatjom 
incredible thinnefs, which forae aftronomers have brought 
from the fliort time of its being invihble, when the eartli 
pafles through its plane, we cannot fet much value upon them ; 
for they muft have fuppofed the edge of the ring, as they have 
alfo reprefented it in their figures, to be fquare ; but there is 
the greateft reafon to fuppofe it either fpherical or fpheroidical, 
in which cafe evidently the ring cannot difappear for any long 
time. Nay, I may venture to fay, that the ring cannot polli- 
bly difappear on account of its thinnefs ; imce, either from the 
ed<re or the fides, even if it were fquare on the corners, it 
muft always expofe to our fight fome part which is illuminated 
by the rays of the fun : and that this is plainly the cafe, we 
may conclude from its being vifible in my telefcopcs during 
the time when others of lels light had loft it, and when evi- 
dently we were turned towards the unenlightened tide, fo that 
we muft either fee the rounding part of the enlightened edge, 
or elfe the refieftion of the light of Saturn upon the fide of the 
darkened ring, as we fee the reflected light of the earth on the 
dark part of the new moon. 1 will, however, not decide 
which of the two may be the cafe; efpecially as there aie 
other very ftrong real'ons to induce us to think, that the edge 
of the ring is of fuch a nature as not to reflect much light. 
I cannot leave this fubjeft without mentioning both my own 
former furmifes, and thofe of feveral other aftronomers, of a 
fuppofed roughnefs in the furface of the ring, or inequality m 
the planes and inclinations of its flat fides. They arote.from 
feeing luminous parts on its extent, which were fuppofed to be 
projecting points, like the moon’s mountains; or from feeing one 
arm brighter or longer than another ; or even from feeing one 
arm when the other was invifible. I was, in the beginning of 
this feafon, inclined to the fame opinion, till one of thefe iup- 
