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Dr. Herschel j s Observations on 
derful a construction ; but my late views of its southern plane* 
assisted by some conclusions drawn from the discovery of the 
quick rotation of the ring, have enabled me to speak decisively 
on this subject. My suspicion of a divided or double ring 
arose chiefly from the following circumstances. 
In the first place, the black belt, during the time of about 
ten years that I observed it, on the northern plane, was sub- 
ject to no kind of change ; but remained always, permanently, 
of the same breadth and colour. With regard to its breadth, 
it is true that I could only judge of that part of it which goes 
across the body of the planet, by the rules of perspective, 
which made me suppose it to be as broad there as it was on 
the two sides ; yet now, as we know that the ring revolves in 
about ten hours and a half, it is very certain, that the appa- 
rently narrow part, across the body, and that which was 
hidden behind the planet, in the course of an evening, when I 
have been observing Saturn for many hours together, must 
have been exposed to view in their full breadth, upon the sides 
of the ring ; and that, if there had been any difference, I must 
have perceived it ; especially as I was continually on the look 
out for such phenomena, by way of ascertaining, if possible, 
the rotation of the ring * 
In the next place, the colour of this dark belt was also uni- 
formly the same, whenever I observed it under equally fa- 
vourable circumstances ; and being so well defined on both its 
* When I say that the black division was always of the same breadth, I do not mean 
to exclude very small variations, not only of the breadth of the black mark, but of the 
ring itself, which I have occasionally observed, and which it may be necessary, here- 
after, to communicate at full length ; but these, almost imperceptible, differences 
might arise from causes that are foreign to our present purpose* 
