process.

"We are not able to ascertain by observation the
constitution of the two outer divisions of the system
of rings, but the inner ring is certainly transparent,
for the limb of Saturn has been observed through it.
It is also certain that though the space occupied by
the ring is transparent, it is not through the material
parts of it that the limb of Saturn is seen, for his limb
was observed without distortion; which shows that
there was no refraction, and, therefore, that the rays
did not pass through a medium at all, but between the
solar or liquid particles of which the ring is composed.
Here, then, we have an optical argument in favor of
the theory of independent particles as the material of
the rings. The two outer rings may be of the same
nature, but not so exceedingly rare that a ray of light
can pass through their whole thickness without encountering
one of the particles.

"Finally, the two outer rings have been observed for
two hundred years, and it appears, from the careful
analysis of all the observations of M. Struve, that the
second ring is broader than when first observed, and
that its inner edge is nearer the planet than formerly.
The inner ring also is suspected to be approaching
the planet ever since its discovery in 1850. These
appearances seem to indicate the same slow progress of
the rings towards separation which we found to be the
result of theory, and the remark that the inner edge