PHILOSOPHICAL 
TRANSACTIONS. 
I. On the Ring of Saturn, and the Rotation of the fi fth Satellite 
upon its Axis. By William Herschel, LL.D. F.R.S. 
Read December 15, 1791. 
It is well known to Astronomers that the ring of Saturn be- 
comes alternately enlightened on one of its sides, and that this 
change of illumination takes place when the planet passes 
through the node of the ring. This happened in October, 
1789, when the southern plane, which had been in the dark 
for about fifteen years, became visible to us: an event to which 
I have looked forwards with considerable impatience. In the 
year 1790, the position of the ring was still too oblique to per- 
mit me to examine it well enough to form a proper judgment 
of its appearance, but lately I have been able to view it to 
greater advantage, with every one of my telescopes. 
In a former paper ,* where I ventured to hint at a division 
of the ring of Saturn, it was highly necessary to express that 
surmise with proper doubts concerning the reality of so won- 
* Phil. Trans. Vol. LXXX. page 4. 
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