6 Dr. Hersciiel’s Obfcrvations , 
while that of the ring ftill remained white. The fame rcfulr 
happened on June 25, 1781, with the power 460. 
I come now to one of the raoft remarkable properties in the 
-conftru&ion of the ring, which is its extreme thinnefs. The 
fituation of Saturn, for fome months pad, has been particu- 
larly favourable for an inveftigation of tins circumftance ; and- 
my experiments have been fo complete, that there can remain 
no doubt on -this head. 
When we were nearly in the plane of the ring, I have- 
repeatedly feen the firft, the fecond, and the third fatellites 
nay even the fixth and leventh, pals before and behind the 
ring in fuch a manner that they ferved as excellent microme- 
ters to eftimate its thicknefs by. It may be proper to men- 
tion a few indances, efpecially as they will lerve to folve iome 
phenomena that have been remarked by other aftronomei>, 
without having been accounted for in any manner that could 
be admitted, confidently with other known fads. July 18, 
1789,, at 19 h. 4 1' 9", lidereal time, the firft fatellite deemed 
to hang upon the following arm, declining a little towards the 
north, and I faw it gradually advance upon it towards the 
body of Saturn.; but the ring was not lo thick as the lucid 
point. July 23, at 19 b. 4T S ', the fecond fatellite was a 
very little preceding the ring ; but the ring appeared to be lefs 
than half the thicknefs of the fatellite. July 27, at 20 h. 
1 12! \ the fecond fatellite was about the middle, upon the 
following arm of the ring, and towards the fouth ; and the 
fixth fatellite on the farther end, towards the north; but the 
arm was thinner than either of them. Auguft 29, at 22 h. 
i.2 / 25", the third fatellite was upon the ring, near the end of 
* the preceding arm ; and my remark at the time when I faw it 
was, that the arm deemed not to be the fourth, at ieaft not the 
thirds part of the diameter of the fatellite, which, in the 
fituation 
